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postgresql-orm 0.5.0 → 0.5.1

raw patch · 31 files changed

+4257/−3926 lines, 31 filesdep +haskell-src-extsdep +postgresql-ormdep +temporarydep ~blaze-builderdep ~postgresql-simple

Dependencies added: haskell-src-exts, postgresql-orm, temporary

Dependency ranges changed: blaze-builder, postgresql-simple

Files

− Data/GetField.hs 
@@ -1,248 +0,0 @@-{-# LANGUAGE Safe #-}-{-# LANGUAGE CPP #-}-{-# LANGUAGE DefaultSignatures #-}-{-# LANGUAGE FlexibleContexts #-}-{-# LANGUAGE FlexibleInstances #-}-{-# LANGUAGE FunctionalDependencies #-}-{-# LANGUAGE MultiParamTypeClasses #-}-#if __GLASGOW_HASKELL__ < 710-{-# LANGUAGE OverlappingInstances #-}-#endif-{-# LANGUAGE RankNTypes #-}-{-# LANGUAGE AllowAmbiguousTypes #-}--- ^ Enables the default implementation of Extractor as of GHC 8.0-{-# LANGUAGE TypeOperators #-}-{-# LANGUAGE UndecidableInstances #-}---- | Functions to extract a field of a particular type from a--- 'Generic' data structure, when the data structure contains exactly--- one field of the given type.  Only works for types with exactly one--- constructor (not variant types).------ An example of usage:------ > data MyType = MyType { myString :: String             -- position 0--- >                      , myInt :: Int                   -- position 1--- >                      , myBool :: Bool                 -- position 2--- >                      , myMaybeChar :: Maybe Char      -- position 3--- >                      , myMaybeString :: Maybe String  -- position 4--- >                      } deriving (Show, Generic)--- > --- > myType :: MyType--- > myType = MyType "my type" 21 True Nothing (Just "maybe string")------ >>> getFieldVal ExtractId myType :: String--- "my type"--- >>> getFieldVal ExtractId myType :: Int--- 21--- >>> getFieldVal ExtractMaybe myType :: Maybe Char--- Nothing--- >>> getFieldVal ExtractMaybe myType :: Maybe Int--- Just 21--- >>> getFieldVal ExtractMaybe myType :: Maybe String  -- ambiguous--- <interactive>:5:1: Couldn't match type `THasMany' with `THasOne'--- >>> getFieldPos' ExtractId (undefined :: MyType) (undefined :: Bool)--- 2--- >>> getFieldPos' ExtractMaybe (undefined :: MyType) (undefined :: Maybe Bool)--- 2--- >>> getFieldPos' ExtractMaybe myType ()  -- No field has type ()--- <interactive>:8:1: Couldn't match type `THasNone' with `THasOne'-module Data.GetField (-  GetField(..), ExtractId(..), ExtractMaybe(..), getFieldPos'-  -- * Internals-  , THasOne(..), THasNone(..), THasMany(..), Extractor(..), GGetField(..)-  ) where--import GHC.Generics---- | Dirty trick to construct "less specific" overlapping instances by--- making a class argument a simple type variable, but constraining--- that variable to be a particular type.  E.g., neither of the--- following two instances is more specific than the other, because--- @NO@ is not more general than @YES@:------ > class MyClass a b c | a b -> c where myClass :: a -> b -> c ()--- > instance MyClass a a YES       where myClass _ _ = YES ()--- > instance MyClass a b NO        where myClass _ _ = NO ()------ Hence, attempting to use the first instance will generate a--- compilation error rather than inferring the type of c as YES.  On--- the other hand, of the following two instances, the first is more--- specific than the second:------ > instance MyClass a a YES where--- >     myClass _ _ = YES ()--- > instance (TypeGCast NO c) => MyClass a b c where--- >     myClass _ _ = typeGCast $ NO ()------ That's because @c@ is more general than @YES@.  The key to this--- working is that an instance context--i.e., @(TypeGCast NO c)@--is--- never consulted during instance selection, only to validate an--- already-selected most-specific instance.------ Note that @YES@ and @NO@ in these examples have kind @* -> *@.--- Hence the @G@ in @TypeGCast@.  The same trick is equally applicable--- to types of kind @*@, we just don't happen to need that in this--- module.-class TypeGCast f g | f -> g where-  typeGCast :: f p -> g p-instance TypeGCast f f where-  typeGCast = id---- | Exactly one matching field has been found.-newtype THasOne a = THasOne { fromTHasOne :: a } deriving (Show)--- | Zero matching fields have been found.-data THasNone a = THasNone deriving (Show)--- | More than one matching field has been found.-newtype THasMany a = THasMany { fromTHasMany :: [a] } deriving (Show)--class GCombine a b c | a b -> c where-  gCombine :: a p -> b p -> c p-instance GCombine THasOne THasNone THasOne where-  {-# INLINE gCombine #-}-  gCombine j _ = j-instance GCombine THasNone THasOne THasOne where-  {-# INLINE gCombine #-}-  gCombine _ j = j-instance GCombine THasNone THasNone THasNone where-  -- Should never be evaluated, so no need to inline it-  gCombine _ _ = THasNone-instance GCombine THasOne THasOne THasMany where-  {-# INLINE gCombine #-}-  gCombine (THasOne a) (THasOne b) = THasMany [a,b]-instance GCombine THasMany THasMany THasMany where-  {-# INLINE gCombine #-}-  gCombine (THasMany as) (THasMany bs) = THasMany (as ++ bs)-instance GCombine THasNone THasMany THasMany where-  {-# INLINE gCombine #-}-  gCombine _ hm = hm-instance GCombine THasMany THasNone THasMany where-  {-# INLINE gCombine #-}-  gCombine hm _ = hm-instance GCombine THasOne THasMany THasMany where-  {-# INLINE gCombine #-}-  gCombine (THasOne a) (THasMany as) = THasMany (a:as)-instance GCombine THasMany THasOne THasMany where-  {-# INLINE gCombine #-}-  gCombine (THasMany as) (THasOne a) = THasMany (as++[a])--class GCount f where gCount :: f p -> (Int, [Int])-instance GCount THasOne where gCount  _ = (1, [0])-instance GCount THasMany where gCount _ = (1, [0])-instance GCount THasNone where gCount _ = (1, [])---- | Class of types used as tag arguments to 'gGetFieldVal' and--- 'gGetFieldPos'.  @f@ should be a new unit type of kind @* -> *@,--- used to designate the type of extraction you want.  Then instances--- should be defined to transform each type @a@ you want to extract to--- some type @r@, with @g@ set to 'THasOne'.------ For example, 'ExtractMaybe' is a type to convert types @a@ and--- @Maybe a@ both to type @Maybe a@ (i.e., type argument @r@ is @Maybe--- a@).------ > data ExtractMaybe a = ExtractMaybe--- > instance Extractor ExtractMaybe a (Maybe a) THasOne where--- >   extract _ = THasOne . Just--- > instance Extractor ExtractMaybe (Maybe a) (Maybe a) THasOne where--- >   extract _ = THasOne------ Note that there is already a default general instance returning--- 'THasNone'.  Hence, you do not need to define one.  Otherwise, you--- would have to define an overlapping instance such as:------ > instance Extractor ExtractMaybe a b THasZero where  -- Incorrect--- >   extract _ = THasNone------ (Except the above wouldn't quite work anyway given the rules for--- overlapping instances.)  So just assume that any instance you don't--- explicitly define for your 'Extractor' will automatically fall back--- to 'THasNone'.-class Extractor f a r g | f a r -> g where-  extract :: f r -> a -> g r-  extractCount :: f r -> a -> (Int, [Int])-  default extractCount :: (GCount g) => f r -> a -> (Int, [Int])-  extractCount fr a = gCount (extract fr a)-instance-  {-# OVERLAPPABLE #-}-  (TypeGCast THasNone g) => Extractor f a r g where-  extract _ _ = typeGCast THasNone-  extractCount _ _ = gCount THasNone---- | Generlized extraction of a field from a 'Generic' data structure.--- Argument @rep@ should generally be the type @'Rep' t@ for some data--- type @t@ whose fields you want to extract.  @r@ is the result type--- you want back from the extraction.  @f@ should be defined such that--- there is an instance of @'Extractor' f a r THasOne@ for each type--- @a@ you want to convert to @r@ and extract.-class GGetField f rep r g | f rep r -> g where-  gGetFieldVal :: f r -> rep p -> g r-  -- ^ Returns zero, one, or multiple values of type @f@ wrapped in-  -- 'THasOne', 'THasNone', or 'THasMany' respectively.-  gGetFieldPos :: f r -> rep p -> (Int, [Int])-  -- ^ Returns @(total, positions)@ where @total@ is the total number-  -- of fields (matching or not) in the structure and @positions@ is a-  -- list of zero-based field numbers of the fields matching target-  -- type @f r@.-instance (Extractor f c r g) => GGetField f (K1 i c) r g where-  {-# INLINE gGetFieldVal #-}-  gGetFieldVal f (K1 c) = extract f c-  gGetFieldPos f (K1 c) = extractCount f c-instance (GGetField f a1 r g1, GGetField f a2 r g2, GCombine g1 g2 g) =>-         GGetField f (a1 :*: a2) r g where-           {-# INLINE gGetFieldVal #-}-           gGetFieldVal f (a1 :*: a2) =-             gCombine (gGetFieldVal f a1) (gGetFieldVal f a2)-           gGetFieldPos f ~(a1 :*: a2) = (n1 + n2, p1 ++ map (n1 +) p2)-             where (n1, p1) = gGetFieldPos f a1-                   (n2, p2) = gGetFieldPos f a2-instance (GGetField f a r g) => GGetField f (M1 i c a) r g where-  {-# INLINE gGetFieldVal #-}-  gGetFieldVal f (M1 a) = gGetFieldVal f a-  gGetFieldPos f ~(M1 a) = gGetFieldPos f a---class (Generic a, GGetField f (Rep a) r THasOne) => GetField f a r where-  -- | Extract the single field matching 'Extractor' @f r@ from a-  -- 'Generic' data structure @a@ with exactly one constructor.-  getFieldVal :: f r -> a -> r-  -- | Extract the 0-based position of the single field matching-  -- 'Extractor' @f r@ within 'Generic' data structure @a@.-  -- Non-strict in both arguments.-  getFieldPos :: f r -> a -> Int-instance (Generic a, GGetField f (Rep a) r THasOne) => GetField f a r where-  {-# INLINE getFieldVal #-}-  getFieldVal f a = fromTHasOne $ gGetFieldVal f (from a)-  getFieldPos f a = head $ snd $ gGetFieldPos f (from a)---- | A variant of 'getFieldPos' in which the type of the field is--- supplied as a non-strict argument.  This may be easier than--- typecasting the extractor argument.  For example, to extract the--- 'Int' from a structure with a single 'Int' field:------ @---       getFieldPos' 'ExtractId' myStruct ('undefined' :: 'Int')--- @-getFieldPos' :: (Generic a, GGetField f (Rep a) r THasOne) =>-                (f ()) -> a -> r -> Int-getFieldPos' f a r = getFieldPos (fixType f r) a-  where fixType :: f () -> r -> f r-        fixType _ _ = undefined---- | An extractor that matches an exact field type.-data ExtractId r = ExtractId deriving (Show)-instance Extractor ExtractId a a THasOne where-  {-# INLINE extract #-}-  extract _ = THasOne---- | An extractor that matches either type @r@ or type @Maybe r@, and,--- in the former case, wraps @Just@ around the value so as always to--- return type @Maybe r@.-data ExtractMaybe r = ExtractMaybe-instance Extractor ExtractMaybe a (Maybe a) THasOne where-  {-# INLINE extract #-}-  extract _ = THasOne . Just-instance Extractor ExtractMaybe (Maybe a) (Maybe a) THasOne where-  {-# INLINE extract #-}-  extract _ = THasOne-
− Data/RequireSelector.hs 
@@ -1,28 +0,0 @@-{-# LANGUAGE FlexibleInstances, UndecidableInstances, CPP #-}--module Data.RequireSelector (RequireSelector) where--#if defined(__GLASGOW_HASKELL__) && (__GLASGOW_HASKELL__ < 800)-import GHC.Generics---- | There are intentionally no members of this class, so that placing--- it in a context will always cause an error.-class IntentionallyCauseError a-#endif---- | The point of this class is to ensure that you are using data--- types defined with record selectors (i.e., @data Foo = Foo { unFoo--- :: Int }@ as opposed to @data Foo = Foo Int@).------ Unfortunately, "GHC.Generics" makes the 'NoSelector' type a member--- of the 'Selector' class.  Hence, if you want to ensure a type @a@--- is /not/ 'NoSelector', use the context @(RequireSelector a) =>@.------ If you see a compilation error involving @RequireSelector@ or--- @IntentionallyCauseError@, it means you failed to define one of--- your datatypes using record selector syntax.-class RequireSelector a-#if defined(__GLASGOW_HASKELL__) && (__GLASGOW_HASKELL__ < 800)-instance (IntentionallyCauseError NoSelector) => RequireSelector NoSelector-#endif-instance RequireSelector a
− Database/PostgreSQL/Describe.hs 
@@ -1,86 +0,0 @@-{-# LANGUAGE OverloadedStrings #-}---- | Utility function for describing a table in the database.-module Database.PostgreSQL.Describe (-  ColumnInfo(..), describeTable-  ) where--import Control.Monad-import qualified Data.ByteString as S-import Data.Int-import qualified Data.Vector as V-import qualified Database.PostgreSQL.Simple.TypeInfo.Static as PG-import Database.PostgreSQL.Simple-import Database.PostgreSQL.Simple.TypeInfo-import Database.PostgreSQL.Simple.Types--data ColumnInfo = ColumnInfo {-    colNum :: !Int16-    -- ^ Internal column number used by PostgreSQL.  Generally these-    -- will be consecutive starting from 1, but this may not be the-    -- case if you have altered a table to delete columns.-  , colName :: S.ByteString-    -- ^ Name of the column-  , colType :: !TypeInfo-    -- ^ Type of the column-  , colNotNull :: !Bool-    -- ^ If 'True', the database cannot contain null.  (This-    -- constraint should always be accurate.)-  , colPrimary :: !Bool-    -- ^ 'True' if this column (and only this column) constitutes the-    -- primary key of the table.  Always 'False' if the primary key-    -- comprises multiple columns (even if this is one of those-    -- columns).-  , colUnique :: !Bool-    -- ^ 'True' if there is a uniqueness constraint on this column.-    -- Not 'True' if this column is part of a uniqueness constraint-    -- involving multiple columns.  (Such multi-column uniqueness-    -- constraints are not reported by this interface.)-  , colReferences :: !(Maybe S.ByteString)-    -- ^ If this there is a foreign key constraint on this column (and-    -- the constraint does not span multiple columns), report the-    -- table referenced by this column.-  } deriving (Show)--defColInfo :: ColumnInfo-defColInfo = ColumnInfo {-    colNum = 0-  , colName = S.empty-  , colType = PG.void-  , colNotNull = False-  , colPrimary = False-  , colUnique = False-  , colReferences = Nothing-  }---- | Returns a list of 'ColumnInfo' structures for a particular table.--- Not all information about a table is returned.  In particular,--- constraints that span columns are ignored.-describeTable :: Connection -> S.ByteString -> IO [ColumnInfo]-describeTable cn t = do-  [(Only tbloid)] <- query cn "select oid from pg_class where relname = ?"-                     (Only t)-  cs0 <- query cn "select attnum, attname, atttypid, attnotnull\-                  \ from pg_attribute\-                  \ where attrelid = ? and attisdropped = 'f' and attnum > 0\-                  \ order by attnum"-                  (Only (tbloid :: Oid))-  cs1 <- forM cs0 $ \ (num, name, typ, notnull) -> do-    ti <- getTypeInfo cn typ-    return defColInfo {-      colNum = num, colName = name, colType = ti, colNotNull = notnull-    }-  constraints <- query cn "select contype, conkey, relname\-                          \ from pg_constraint left join pg_class\-                          \ on confrelid = pg_class.oid\-                          \ where conrelid = ?"-                          (Only tbloid)-  let _ = constraints :: [(String, V.Vector Int16, Maybe S.ByteString)]-  return $ map (\c -> foldl appConstr c constraints) cs1-    where appConstr ci (ct, ck, mn)-            | V.length ck == 1, colNum ci == ck V.! 0 = appConstr1 ci ct mn-            | otherwise                           = ci-          appConstr1 ci "p" _ = ci { colPrimary = True }-          appConstr1 ci "u" _ = ci { colUnique = True }-          appConstr1 ci "f" n@(Just _) = ci { colReferences = n }-          appConstr1 ci _ _ = ci
− Database/PostgreSQL/Devel.hs 
@@ -1,218 +0,0 @@-{-# LANGUAGE CPP #-}-{-# LANGUAGE OverloadedStrings #-}---- | Functions for initializing self-contained local postgreSQL--- database clusters (useful in development more than production).-module Database.PostgreSQL.Devel (-      createLocalDB, configLocalDB, startLocalDB-    , initLocalDB, stopLocalDB, setLocalDB-    , withTempDB-    , resetConnection-  ) where--import Control.Exception-import Control.Monad-#if __GLASGOW_HASKELL__ < 710-import Data.Functor-#endif-import Data.List-import Database.PostgreSQL.Simple-import System.Directory-import System.Exit-import System.FilePath-import System.IO-import System.IO.Error-import System.Posix.Env-import System.Posix.Temp-import System.Process--isNonEmptyDir :: FilePath -> IO Bool-isNonEmptyDir dir =-  catchJust (\e -> if isDoesNotExistError e then Just () else Nothing)-  ((> 2) . length <$> getDirectoryContents dir)-  (const $ return False)--addDirectives :: [(String, String)] -> [String] -> [String]-addDirectives directives [] = map snd directives-addDirectives directives (cl:cls)-  | Just l <- lookup directive directives =-      (if comment then [l, cl] else [l]) ++-      addDirectives (directives \\ [(directive,l)]) cls-  | otherwise = cl : addDirectives directives cls-  where (comment, directive)-          | '#':clr <- cl, [(d,_)] <- lex clr = (True, d)-          | [(d,_)] <- lex cl                 = (False, d)-          | otherwise                         = (False, "")---- | Set configuration parameters on a database by editing the--- @postgresql.conf@ file.  Takes the database directory and a list of--- @(@/parameter/@,@ /full-line/@)@ pairs.  For example, when creating--- a throw-away database cluster you later intend to discard, you--- might say:------ > configLocalDB dbpath [("fsync", "fsync = off")]------ Note that the second element of each pair is the complete--- configuration line.  It is not correct to say:------ > configLocalDB dbpath [("fsync", "off")]   -- INCORRECT----configLocalDB :: FilePath -> [(String, String)] -> IO ()-configLocalDB dir directives = do-  let confpath = dir </> "postgresql.conf"-  oldconf <- lines <$> readFile confpath-  let conf = unlines $ addDirectives directives oldconf-  length conf `seq` writeFile confpath conf--singleQuote :: String -> String-singleQuote ('\'':t) = "''" ++ singleQuote t-singleQuote (h:t)    = h : singleQuote t-singleQuote []       = ""--pgDirectives :: FilePath -> [(String, String)]-pgDirectives dir = [-    ("unix_socket_directories"-    , "unix_socket_directories = '" ++ singleQuote dir ++ "'")-  , ("logging_collector",  "logging_collector = yes")-  , ("listen_addresses", "listen_addresses = ''")]--pgDirectives92 :: FilePath -> [(String, String)]-pgDirectives92 dir = map depluralize $ pgDirectives dir-  where depluralize ("unix_socket_directories", _) =-          ("unix_socket_directory"-          , "unix_socket_directory = '" ++ singleQuote dir ++ "'")-        depluralize kv = kv---- | Create a directory for a local database cluster entirely--- self-contained within one directory.  This is accomplished by--- creating a new PostgreSQL database cluster in the directory and--- setting the following configuration options in @postgresql.conf@:------ * @listen_address@ is set to empty (i.e., @\'\'@), so that no TCP--- socket is bound, avoiding conflicts with any other running instaces--- of PostgreSQL.------ * @logging_collector@ is set to @yes@, so that all message logs are---   kept in the @pg_log@ subdirectory of the directory you specified.------ Note this function does /not/ start a postgres server after--- creating the directory.  You will seperately need to start the--- server using 'startLocalDB' or 'initLocalDB'.  (And note that--- 'initLocalDB' already calls @createLocalDB@ if the directory does--- not exist or is empty.  Hence the primary use of this function is--- if you want to call 'configLocalDB' between 'createLocalDB' and--- 'startLocalDB'.)-createLocalDB :: FilePath -> IO ()-createLocalDB dir = do-  (exit, _, err) <- readProcessWithExitCode "pg_ctl"-                      ["-D", dir, "-o", "--no-locale", "init"] ""-  when (exit /= ExitSuccess) $ fail err-  dir' <- canonicalizePath dir-  writeFile (dir </> "README_BEFORE_DELETING") $-    "## IMPORTANT:  Run the following command before deleting this " ++-    "directory ##\n\n" ++-    "pg_ctl -D " ++ showCommandForUser dir' [] ++ " stop -m immediate\n\n"-  version <- readFile (dir </> "PG_VERSION")-  case reads version of-    [(v, _)] | v < (9.3 :: Double) -> configLocalDB dir $ pgDirectives92 dir'-    _                              -> configLocalDB dir $ pgDirectives dir'--systemNoStdout :: String -> [String] -> IO ExitCode-systemNoStdout prog args =-  bracket (openFile "/dev/null" ReadWriteMode) hClose $ \devnull -> do-    let cp = (proc prog args) { std_in = UseHandle devnull-                              , std_out = UseHandle devnull }-    (_,_,_,pid) <- createProcess cp-    waitForProcess pid---- | Start a local database if the server is not already running.--- Otherwise, does nothing, but returns a 'ConnectInfo' in either--- case.  The database server will continue running after the current--- process exits (but see 'stopLocalDB').-startLocalDB :: FilePath -> IO ConnectInfo-startLocalDB dir0 = do-  dir <- canonicalizePath dir0-  (e0, _, _) <- readProcessWithExitCode "pg_ctl" ["status", "-D", dir] ""-  when (e0 /= ExitSuccess) $ do-    e1 <- systemNoStdout "pg_ctl" [ "start", "-w", "-D", dir ]-    when (e1 /= ExitSuccess) $ fail "could not start postgres"-  return defaultConnectInfo { connectHost = dir-                            , connectUser = ""-                            , connectDatabase = "postgres"-                            }---- | A combination of 'createLocalDB' and 'startLocalDB'.------ The parameter is a PostgreSQL data directory.  If the directory is--- empty or does not exist, this function creates a new database--- cluster (via 'createLocalDB').  Then, if a database server is not--- already running for the directory, starts a server.  No matter--- what, returns a 'ConnectInfo' that will connect to the server--- running on this local database.------ Note that if @initLocalDB@ starts a postgres server, the server--- process will continue running after the process that called--- @initLocalDB@ exits.  This is normally fine.  Since multiple client--- processes may access the same PostgreSQL database, it makes sense--- for the first client to start the database and no one to stop it.--- See 'stopLocalDB' if you wish to stop the server process (which you--- should always do before deleting a test cluster).  See also--- 'withTempDB' to create a temporary cluster for the purposes of--- running a test suite.-initLocalDB :: FilePath -> IO ConnectInfo-initLocalDB dir = do-  exists <- isNonEmptyDir dir-  unless exists $ createLocalDB dir-  startLocalDB dir---- | Stop the server for a local database cluster entirely--- self-contained within one directory.  You must call this before--- deleting the directory, or else stray postgres processes will--- linger forever.  If the argument is the empty string, looks for the--- database directory in the @PGDATA@ environment variable.-stopLocalDB :: FilePath -> IO ()-stopLocalDB dir0 = do-  dir <- if not (null dir0) then return dir0 else do-    mpgd <- getEnv "PGDATA"-    case mpgd of Just pgd -> return pgd-                 _        -> fail "stopLocalDB: must specify database"-  e <- systemNoStdout "pg_ctl" ["stop", "-D", dir, "-m", "fast"]-  when (e /= ExitSuccess) $ fail "could not stop postgres"---- | Set environment variables to make a local database cluster the--- default.  Also returns shell commands you can eval or cut-and-paste--- into your shell to make @pg_ctl@ and @psql@ access a local database--- cluster.-setLocalDB :: FilePath -> IO String-setLocalDB dir0 = do-  dir1 <- canonicalizePath dir0-  setEnv "PGHOST" dir1 True-  setEnv "PGDATA" dir1 True-  setEnv "PGDATABASE" "postgres" True-  let dir = showCommandForUser dir1 []-  msh <- getEnv "SHELL"-  return $ case msh of Just sh | isSuffixOf "csh" sh ->-                         "setenv PGDATA " ++ dir ++ "; setenv PGHOST " ++ dir-                       _ -> "export PGDATA=" ++ dir ++ " PGHOST=" ++ dir---- | Run a function with a completely fresh database cluster that gets--- deleted on return.  Since the entire database is blown away when--- the function returns, @withTempDB@ is obviously only useful for--- test suites.-withTempDB :: (ConnectInfo -> IO a) -> IO a-withTempDB f = bracket createdir removeDirectoryRecursive $ \d ->-  flip finally (stopLocalDB d) $ do-    createLocalDB d-    configLocalDB d [("fsync", "fsync = off")-                    , ("synchronous_commit", "synchronous_commit = off")-                    , ("full_page_writes", "full_page_writes = off")]-    initLocalDB d >>= f-  where createdir = do-          tmp <- getTemporaryDirectory-          mkdtemp $ tmp </> "db."---- | Reset a connection to its default state before re-cycling it for--- another thread or request.-resetConnection :: Connection -> IO ()-resetConnection c = (void $ execute_ c "DISCARD ALL") `catch` \SqlError{} ->-  void $ execute_ c "ROLLBACK" >> execute_ c "DISCARD ALL"
− Database/PostgreSQL/Escape.hs 
@@ -1,270 +0,0 @@-{-# LANGUAGE Trustworthy #-}-{-# LANGUAGE BangPatterns #-}-{-# LANGUAGE MagicHash #-}-{-# LANGUAGE OverloadedStrings #-}-{-# LANGUAGE UnboxedTuples #-}-{-# LANGUAGE CPP #-}--#include "MachDeps.h"---- | This module deals with escaping and sanitizing SQL templates.-module Database.PostgreSQL.Escape (-    fmtSql, quoteIdent-  , buildSql, buildSqlFromActions-  , buildAction, buildLiteral, buildByteA, buildIdent-  ) where--import Blaze.ByteString.Builder.Internal.Write-import Data.ByteString.Builder-import Data.ByteString.Builder.Internal-import Data.ByteString.Lazy (toStrict)-import qualified Data.ByteString as S-import qualified Data.ByteString.Internal as S-import qualified Data.ByteString.Unsafe as S-import Data.Monoid-import Database.PostgreSQL.Simple-import Database.PostgreSQL.Simple.ToField-import Database.PostgreSQL.Simple.ToRow-import Database.PostgreSQL.Simple.Types-import Foreign.Marshal.Alloc (mallocBytes)-import Foreign.Storable (pokeByteOff)-import Foreign.Ptr-import GHC.Prim (Addr#, and#, geAddr#, geWord#, Int#, int2Word#-                , minusAddr#, ord# , plusAddr#, readWord8OffAddr#-                , State# , uncheckedShiftRL#, word2Int#, writeWord8OffAddr#-                , Word#)-import GHC.Ptr (Ptr(Ptr))-import GHC.Types (Char(C#), Int(I#), IO(IO))-import GHC.Word (Word8(W8#))-import System.IO.Unsafe (unsafeDupablePerformIO)--{-# INLINE cmpres #-}--- | Newer versions of GHC return an Int# instead of a Bool for--- primitive comparison functions.  The @cmpres@ function converts the--- result of such a comparison to a @Bool@.-#if __GLASGOW_HASKELL__ >= 707-cmpres :: Int# -> Bool-cmpres 0# = False-cmpres _ = True-#else /* __GLASGOW_HASKELL__ < 707 */-cmpres :: Bool -> Bool-cmpres b = b-#define cmpres(b) b-#endif /* __GLASGOW_HASKELL__ < 707 */--c2b :: Char -> Word8-c2b (C# i) = W8# (int2Word# (ord# i))--c2b# :: Char -> Word#-c2b# (C# i) = int2Word# (ord# i)--inlinePerformIO :: IO a -> a-#if MIN_VERSION_bytestring(0,10,6)-inlinePerformIO = S.accursedUnutterablePerformIO-#else-inlinePerformIO = S.inlinePerformIO-#endif--fastFindIndex :: (Word# -> Bool) -> S.ByteString -> Maybe Int-{-# INLINE fastFindIndex #-}-fastFindIndex test bs =-  inlinePerformIO $ S.unsafeUseAsCStringLen bs $ \(Ptr bsp0, I# bsl0) -> do-    let bse = bsp0 `plusAddr#` bsl0-        check bsp = IO $ \rw -> case readWord8OffAddr# bsp 0# rw of-          (# rw1, w #) -> (# rw1, test w #)-        go bsp | cmpres(bsp `geAddr#` bse) = return Nothing-               | otherwise = do-                 match <- check bsp-                 if match-                   then return $ Just $ I# (bsp `minusAddr#` bsp0)-                   else go (bsp `plusAddr#` 1#)-    go bsp0--fastBreak :: (Word# -> Bool) -> S.ByteString -> (S.ByteString, S.ByteString)-{-# INLINE fastBreak #-}-fastBreak test bs-  | Just n <- fastFindIndex test bs = (S.unsafeTake n bs, S.unsafeDrop n bs)-  | otherwise                       = (bs, S.empty)--quoter :: S.ByteString -> S.ByteString -> (Word# -> Bool)-          -> (Word8 -> Builder) -> S.ByteString -> Builder-{-# INLINE quoter #-}-quoter start end escPred escFn bs0 =-  mconcat [byteStringCopy start, escaped bs0, byteStringCopy end]-  where escaped bs = case fastBreak escPred bs of-          (h, t) | S.null t  -> byteString h-                 | otherwise -> byteString h <>-                                escFn (S.unsafeHead t) <>-                                escaped (S.unsafeTail t)---- | Quote an identifier using unicode quoting syntax.  This is--- necessary for identifiers containing a question mark, as otherwise--- "PostgreSQL.Simple"'s naive formatting code will attempt to match--- the question mark to a paremeter.-uBuildIdent :: S.ByteString -> Builder-uBuildIdent ident = quoter " U&\"" "\"" isSpecial esc ident-  where isSpecial 34## = True   -- '"'-        isSpecial 63## = True   -- '?'-        isSpecial 92## = True   -- '\\'-        isSpecial _    = False-        esc c = byteStringCopy $ case () of-          _ | c == c2b '"'  -> "\"\""-            | c == c2b '?'  -> "\\003f"-            | c == c2b '\\' -> "\\\\"-            | otherwise     -> error "uquoteIdent"---- | Build a quoted identifier.  Generally you will want to use--- 'quoteIdent', and for repeated use it will be faster to use--- @'byteString' . 'quoteIdent'@, but this internal function is--- exposed in case it is useful.-buildIdent :: S.ByteString -> Builder-buildIdent ident-  | Just _ <- fastFindIndex isQuestionmark ident = uBuildIdent ident-  | otherwise = quoter "\"" "\"" isDQuote (const $ byteStringCopy "\"\"") ident-  where isQuestionmark 63## = True-        isQuestionmark 0##  = error "quoteIdent: illegal NUL character"-        isQuestionmark _    = False-        isDQuote 34## = True-        isDQuote _    = False---- | Quote an identifier such as a table or column name using--- double-quote characters.  Note this has nothing to do with quoting--- /values/, which must be quoted using single quotes.  (Anyway, all--- values should be quoted by 'query' or 'fmtSql'.)  This function--- uses a unicode escape sequence to escape \'?\' characters, which--- would otherwise be expanded by 'query', 'formatQuery', or 'fmtSql'.------ >>> S8.putStrLn $ quoteIdent "hello \"world\"!"--- "hello ""world""!"--- >>> S8.putStrLn $ quoteIdent "hello \"world\"?"---  U&"hello ""world""\003f"------ Note that this quoting function is correct only if--- @client_encoding@ is @SQL_ASCII@, @client_coding@ is @UTF8@, or the--- identifier contains no multi-byte characters.  For other coding--- schemes, this function may erroneously duplicate bytes that look--- like quote characters but are actually part of a multi-byte--- character code.  In such cases, maliciously crafted identifiers--- will, even after quoting, allow injection of arbitrary SQL commands--- to the server.------ The upshot is that it is unwise to use this function on identifiers--- provided by untrustworthy sources.  Note this is true anyway,--- regardless of @client_encoding@ setting, because certain \"system--- column\" names (e.g., @oid@, @tableoid@, @xmin@, @cmin@, @xmax@,--- @cmax@, @ctid@) are likely to produce unexpected results even when--- properly quoted.------ See 'Id' for a convenient way to include quoted identifiers in--- parameter lists.-quoteIdent :: S.ByteString -> S.ByteString-quoteIdent = toStrict . toLazyByteString . buildIdent--hexNibblesPtr :: Ptr Word8-{-# NOINLINE hexNibblesPtr #-}-hexNibblesPtr = unsafeDupablePerformIO $ do-  ptr <- mallocBytes 16-  sequence_ $ zipWith (\o v -> pokeByteOff ptr o $ c2b v)-    [0..] (['0'..'9'] ++ ['a'..'f'])-  return ptr---- | Bad things will happen if the argument is greater than 0xff.-uncheckedWriteNibbles# :: Addr# -> Word# -> State# d -> State# d-{-# INLINE uncheckedWriteNibbles# #-}-uncheckedWriteNibbles# p w rw0 =-  case (# word2Int# (w `uncheckedShiftRL#` 4# )-       , word2Int# (w `and#` 0xf## ) #) of { (# h, l #) ->-  case readWord8OffAddr# nibbles h rw0 of { (# rw1, hascii #) ->-  case writeWord8OffAddr# p 0# hascii rw1 of { rw2 ->-  case readWord8OffAddr# nibbles l rw2 of { (# rw3, lascii #) ->-  writeWord8OffAddr# p 1# lascii rw3 }}}}-  where !(Ptr nibbles) = hexNibblesPtr--hexCharEscBuilder :: Word8 -> Builder-{-# INLINE hexCharEscBuilder #-}-hexCharEscBuilder (W8# w) = fromWrite $ exactWrite 4 $ \(Ptr p) -> IO $ \rw0 ->-  (# uncheckedWriteNibbles# (p `plusAddr#` 2#) w-   (writeWord8OffAddr# p 1# (c2b# 'x')-    (writeWord8OffAddr# p 0# (c2b# '\\') rw0))-  , () #)--buildLiteral :: S.ByteString -> Builder-buildLiteral = quoter " E'" "'" isSpecial esc-  where isSpecial 39## = True   -- '\''-        isSpecial 63## = True   -- '?'-        isSpecial 92## = True   -- '\\'-        isSpecial b    = cmpres(b `geWord#` 128##)-        esc b | b == c2b '\'' = byteStringCopy "''"-              | b == c2b '\\' = byteStringCopy "\\\\"-              | otherwise     = hexCharEscBuilder b---copyByteToNibbles :: Addr# -> Addr# -> IO ()-{-# INLINE copyByteToNibbles #-}-copyByteToNibbles src dst = IO $ \rw0 ->-  case readWord8OffAddr# src 0# rw0 of-    (# rw1, w #) -> (# uncheckedWriteNibbles# dst w rw1, () #)--buildByteA :: S.ByteString -> Builder-buildByteA bs = equote $-  builder $ \cont (BufferRange (Ptr bb0) (Ptr be0)) ->-    S.unsafeUseAsCStringLen bs $ \(Ptr inptr0, I# inlen0) -> do-    let ine = plusAddr# inptr0 inlen0-        fill oute inp outp-          | cmpres(inp `geAddr#` ine) = cont (BufferRange (Ptr outp) (Ptr oute))-          | cmpres(plusAddr# outp 2# `geAddr#` oute) = return $-              bufferFull (2 * (I# (ine `minusAddr#` inp)) + 1) (Ptr outp) $-              \(BufferRange (Ptr bb) (Ptr be)) -> fill be inp bb-          | otherwise = do copyByteToNibbles inp outp-                           fill oute (inp `plusAddr#` 1#) (outp `plusAddr#` 2#)-    fill be0 inptr0 bb0-  where equote b = mconcat [byteString " E'\\\\x", b, char8 '\'']----buildAction :: Action -> Builder-buildAction (Plain b)             = b-buildAction (Escape bs)           = buildLiteral bs-buildAction (EscapeByteA bs)      = buildByteA bs-buildAction (EscapeIdentifier bs) = buildIdent bs-buildAction (Many bs)             = mconcat $ map buildAction bs---- | A lower-level function used by 'buildSql' and 'fmtSql'.  You--- probably don't need to call it directly.-buildSqlFromActions :: Query -> [Action] -> Builder-buildSqlFromActions (Query template) actions =-  intercatlate (split template) (map buildAction $ actions)-  where intercatlate (t:ts) (p:ps) = t <> p <> intercatlate ts ps-        intercatlate [t] []        = t-        intercatlate _ _           =-          error $ "buildSql: wrong number of parameters for " ++ show template-        split s = case S.break (== c2b '?') s of-          (h,t) | S.null t  -> [byteString h]-                | otherwise -> byteString h : split (S.unsafeTail t)---- | A builder version of 'fmtSql', possibly useful if you are about--- to concatenate various individually formatted query fragments and--- want to save the work of concatenating each individually.-buildSql :: (ToRow p) => Query -> p -> Builder-{-# INLINE buildSql #-}-buildSql q p = buildSqlFromActions q (toRow p)---- | Take a SQL template containing \'?\' characters and a list of--- paremeters whose length must match the number of \'?\' characters,--- and format the result as an escaped 'S.ByteString' that can be used--- as a query.------ Like 'formatQuery', this function is naive about the placement of--- \'?\' characters and will expand all of them, even ones within--- quotes.  To avoid this, you must use 'quoteIdent' on identifiers--- containing question marks.------ Also like 'formatQuery', \'?\' characters touching other \'?\'--- characters or quoted strings may do the wrong thing, and end up--- doubling a quote, so avoid substrings such as @\"??\"@ or--- @\"?'string'\"@, as these could get expanded to, e.g.,--- @\"\'param''string'\"@, which is a single string containing an--- apostrophe, when you probably wanted two strings.-fmtSql :: (ToRow p) => Query -> p -> Query-{-# INLINE fmtSql #-}-fmtSql q p = Query $ toStrict . toLazyByteString $ buildSql q p
− Database/PostgreSQL/Migrate.hs 
@@ -1,172 +0,0 @@-{-# LANGUAGE CPP, OverloadedStrings #-}---- | Functions for creating and running database migrations. You should--- probably be using the `pg_migrate` executable to run migrations, however--- these functions are exposed for developers that want to integrate migrations--- more tightly into their applications or utilities.--module Database.PostgreSQL.Migrate-  ( initializeDb-  , runMigrationsForDir-  , runRollbackForDir-  , dumpDb-  , newMigration-  , defaultMigrationsDir-  , MigrationDetails(..)-  ) where--import Control.Monad-import Data.List-import Data.Time-import Database.PostgreSQL.Simple hiding (connect)-import qualified Data.ByteString.Char8 as S8-import Database.PostgreSQL.Migrations-import System.Exit -import GHC.IO.Handle-import System.Process-import System.Directory-import System.FilePath-import System.Environment-import System.IO-#if !MIN_VERSION_time(1,5,0)-import System.Locale-#endif--import Paths_postgresql_orm---- | The default relative path containing migrations: @\"db\/migrations\"@-defaultMigrationsDir :: FilePath-defaultMigrationsDir = "db" </> "migrations"---- | Dumps the database schema to the given file handle.------ This is a wrapper around the utility /pg_dump/ that comes with postgresql.--- Therefore, /pg_dump/ must be installed on the system.-dumpDb :: Handle -> IO ExitCode-dumpDb outputFile = do-  let opts = ["--schema-only", "-O", "-x"]-  e <- getEnvironment-  let args = case lookup "DATABASE_URL" e of-               Just dburl -> dburl:opts-               Nothing -> opts-  (_, out, err, ph) <- runInteractiveProcess "pg_dump" args Nothing Nothing-  exitCode <- waitForProcess ph-  if exitCode /= ExitSuccess then do-    S8.hGetContents err >>= S8.hPut stderr-    else do-      raw <- S8.hGetContents out-      let clean = S8.concat $ intersperse "\n" $-                    filter ((/= "--") . (S8.take 2)) $-                    S8.lines raw-      S8.hPut outputFile clean-  return exitCode---- | Initializes the database by creating a \"schema-migrations\" table.--- This table must exist before running any migrations.-initializeDb :: IO ()-initializeDb = do-  conn <- connectEnv-  void $ execute_ conn-    "create table if not exists schema_migrations (version VARCHAR(28))"---- | Runs all new migrations in a given directory and dumps the--- resulting schema to a file \"schema.sql\" in the migrations--- directory.------ Determining which migrations to run is done by querying the database for the--- largest version in the /schema_migrations/ table, and choosing all--- migrations in the given directory with higher versions.-runMigrationsForDir :: Handle -- ^ Log output (probably stdout)-                    -> FilePath -- ^ Path to directory containing migrations-                    -> IO ExitCode-runMigrationsForDir logOut dir = do-  conn <- connectEnv-  res <- query_ conn-          "select version from schema_migrations order by version desc limit 1"-  let latestVersion = case res of-                        [] -> ""-                        (Only latest):_ -> latest-  migrations <- getDirectoryMigrations dir >>=-                    return . (dropWhile (isVersion (<= latestVersion)))-  go migrations-  where go [] = withFile (dir </> ".." </> "schema.sql") WriteMode dumpDb-        go (mig@(MigrationDetails _ _ name):fs) = do-              hPutStrLn logOut $ "=== Running Migration " ++ name-              exitCode <- runMigration mig-              if exitCode == ExitSuccess then do-                hPutStrLn logOut "=== Success"-                go fs-                else do-                  hPutStrLn logOut "=== Migration Failed!"-                  return exitCode---- | Run a migration. The returned exit code denotes the success or failure of--- the migration.-runMigration :: MigrationDetails -> IO ExitCode-runMigration (MigrationDetails file vers _) = do-  rawSystem "runghc"-    [file, "up", vers, "--with-db-commit"]--runRollbackForDir :: FilePath -> IO ExitCode-runRollbackForDir dir = do-  conn <- connectEnv-  res <- query_ conn-          "select version from schema_migrations order by version desc limit 1"-  case res of-    [] -> do-      putStrLn "=== DB Fully Rolled Back!"-      return ExitSuccess-    (Only latest):_ -> do-      (Just (mig@(MigrationDetails _ _ name))) <--                  getDirectoryMigrations dir >>=-                    return . (find (isVersion (== latest)))-      putStrLn $ "=== Running Rollback " ++ name-      exitCode <- runRollback mig-      if exitCode == ExitSuccess then do-        putStrLn "=== Success"-        withFile (dir </> ".." </> "schema.sql") WriteMode dumpDb-        else do-          putStrLn "=== Migration Failed!"-          return exitCode---- | Run a migration. The returned exit code denotes the success or failure of--- the migration.-runRollback :: MigrationDetails -> IO ExitCode-runRollback (MigrationDetails file vers _) = do-  rawSystem "runghc"-    [file, "down", vers, "--with-db-commit"]--data MigrationDetails = MigrationDetails { migrationPath :: FilePath-                                         , migrationVersion :: String-                                         , migrationName :: String }-                                         deriving (Show)--getDirectoryMigrations :: FilePath -> IO [MigrationDetails]-getDirectoryMigrations dir = do-  files0 <- getDirectoryContents dir-  let files = filter (('.' /=) . head) $ sort files0-  return $ map (splitFileVersionName dir) files--splitFileVersionName :: FilePath -> FilePath -> MigrationDetails-splitFileVersionName dir file = -  let fileName = takeBaseName file-      parts    = foldr (\chr (hd:result) ->-                          if chr == '_' then-                            "":hd:result-                            else ((chr:hd):result))-                       [""] fileName-      vers  = head parts-      name     = concat $ intersperse "_" $ tail parts-  in MigrationDetails (dir </> file) vers name--isVersion :: (String -> Bool) -> MigrationDetails -> Bool-isVersion cond (MigrationDetails _ v _) = cond v--newMigration :: FilePath -> FilePath -> IO ()-newMigration baseName dir = do-  now <- getZonedTime-  let filePath = (formatTime defaultTimeLocale "%Y%m%d%H%M%S" now) ++-                 "_" ++ baseName ++ ".hs"-  origFile <- getDataFileName "static/migration.hs"-  copyFile origFile (dir </> filePath)-
− Database/PostgreSQL/Migrations.hs 
@@ -1,415 +0,0 @@-{-# LANGUAGE OverloadedStrings #-}--{- |-Functions to help with building database migrations.--Most users will want to create a database migration using @defaultMain@ as-follows,-->-> import Database.PostgreSQL.Migrations->-> main = defaultMain up down->-> up = migrate $ do->       create_table "posts"->         [ column "title" "VARCHAR(255) NOT NULL"->         , column "author_id" "integer references authors(id)"]-> -> down = migrate $ drop_table "posts"->--}-module Database.PostgreSQL.Migrations (-    -- * Utilities-    defaultMain-  , connectEnv-  , runSqlFile-    -- * DSL-  , Migration, migrate-  , column-    -- ** Adding-  , create_table-  , add_column-  , create_index-  , create_unique_index-    -- ** Removing-  , drop_table-  , drop_column-  , drop_index-    -- ** Modifying-  , rename_column-  , change_column-    -- ** Statements-  , create_table_stmt, add_column_stmt, create_index_stmt-  , drop_table_stmt, drop_column_stmt, drop_index_stmt-  , rename_column_stmt, change_column_stmt-  ) where--import Control.Monad-import Control.Monad.Reader-import qualified Data.ByteString as S-import qualified Data.ByteString.Char8 as S8-import Data.Int-import Data.Maybe-import Database.PostgreSQL.Simple hiding (connect)-import Database.PostgreSQL.Simple.Internal (exec)-import Database.PostgreSQL.Simple.Types-import System.Environment-import System.Exit--import Database.PostgreSQL.Escape---- | Creates a PostgreSQL 'Connection' using the /DATABASE_URL/ environment--- variable, if it exists. If it does, it should match the format:------ @---   postgresql:\/\/[[USERNAME\@PASSWORD]HOSTNAME[:PORT]]/[DBNAME]--- @------ If it is not present, the environment variables /PG_DBNAME/ /PG_HOST/ etc,--- are used.-connectEnv :: IO Connection-connectEnv = do-  psqlStr <- getEnvironment >>=-             return . (fromMaybe "") . (lookup "DATABASE_URL")-  connectPostgreSQL $ S8.pack psqlStr------- Migration Monad-----type Migration = ReaderT Connection IO--migrate :: Migration a -> Connection -> IO ()-migrate = (void .) . runReaderT--executeQuery_ :: Query -> Migration Int64-executeQuery_ q = ask >>= \conn -> liftIO $ execute_ conn q---- | Runs the SQL file at the given path, relative to the current working--- directory.-runSqlFile :: FilePath -> Migration ()-runSqlFile sqlFile = void $ do-    conn <- ask-    liftIO $ do-      rawSql <- S.readFile sqlFile-      exec conn rawSql---- | Returns a column defition by quoting the given name-column :: S8.ByteString -- ^ name-       -> S8.ByteString -- ^ type, definition, constraints-       -> S8.ByteString-column name def = S8.concat [quoteIdent name, " ", def]---- | Creates a table. See 'column' for constructing the column list.-create_table :: S8.ByteString-             -- ^ Table name-             -> [S8.ByteString]-             -- ^ Column definitions-             -> Migration Int64-create_table = (executeQuery_ .) . create_table_stmt---- | Returns a 'Query' that creates a table, for example:------ @---   create_table \"posts\"---     [ column \"title\" \"VARCHAR(255) NOT NULL\"---     , column \"body\"  \"text\"]--- @-create_table_stmt :: S8.ByteString-                  -- ^ Table name-                  -> [S8.ByteString]-                  -- ^ Column definitions-                  -> Query-create_table_stmt tableName colDefs = Query $ S8.concat $-  [ "create table "-  , quoteIdent tableName-  , " ("] ++ (S8.intercalate ", " colDefs):([");"])---- | Drops a table-drop_table :: S8.ByteString -> Migration Int64-drop_table = executeQuery_ . drop_table_stmt---- | Returns a 'Query' that drops a table-drop_table_stmt :: S8.ByteString -> Query-drop_table_stmt tableName = Query $ S8.concat-  [ "drop table ", quoteIdent tableName, ";"]---- | Adds a column to the given table. For example,------ @---   add_column \"posts\" \"title\" \"VARCHAR(255)\"--- @------ adds a varchar column called \"title\" to the table \"posts\".----add_column :: S8.ByteString-           -- ^ Table name-           -> S8.ByteString-           -- ^ Column name-           -> S8.ByteString-           -- ^ Column definition-           -> Migration Int64-add_column  = ((executeQuery_ .) .) . add_column_stmt---- | Returns a 'Query' that adds a column to the given table. For example,------ @---   add_column \"posts\" \"title\" \"VARCHAR(255)\"--- @------ Returns the query------ @---   ALTER TABLE \"posts\" add \"title\" VARCHAR(255);--- @-add_column_stmt :: S8.ByteString-                -- ^ Table name-                -> S8.ByteString-                -- ^ Column name-                -> S8.ByteString-                -- ^ Column definition-                -> Query-add_column_stmt tableName colName colDef = Query $ S8.concat-  [ "alter table ", quoteIdent tableName, " add ", column colName colDef, ";"]---- | Drops a column from the given table. For example,------ @---   drop_column \"posts\" \"title\"--- @------ drops the column \"title\" from the \"posts\" table.-drop_column :: S8.ByteString-            -- ^ Table name-            -> S8.ByteString-            -- ^ Column name-            -> Migration Int64-drop_column = (executeQuery_ .) . drop_column_stmt---- | Returns a 'Query' that drops a column from the given table. For example,------ @---   drop_column \"posts\" \"title\"--- @------ Returns the query------ @---   ALTER TABLE \"posts\" add \"title\";--- @-drop_column_stmt :: S8.ByteString-                 -- ^ Table name-                 -> S8.ByteString-                 -- ^ Column name-                 -> Query-drop_column_stmt tableName colName = Query $ S8.concat-  ["alter table ", quoteIdent tableName, " drop ", quoteIdent colName, ";"]---- | Renames a column in the given table. For example,------ @---   rename_column \"posts\" \"title\" \"name\"--- @------ renames the column \"title\" in the \"posts\" table to \"name\".-rename_column :: S8.ByteString-              -- ^ Table name-              -> S8.ByteString-              -- ^ Old column name-              -> S8.ByteString-              -- ^ New column name-              -> Migration Int64-rename_column = ((executeQuery_ .) .) . rename_column_stmt---- | Returns a 'Query' that renames a column in the given table. For example,------ @---   rename_column \"posts\" \"title\" \"name\"--- @------ Returns the query------ @---   ALTER TABLE \"posts\" RENAME \"title\" TO \"name\";--- @-rename_column_stmt :: S8.ByteString-                   -- ^ Table name-                   -> S8.ByteString-                   -- ^ Old column name-                   -> S8.ByteString-                   -- ^ New column name-                   -> Query-rename_column_stmt tableName colName colNameNew = Query $ S8.concat-  [ "alter table ", quoteIdent tableName, " rename "-  , quoteIdent colName, " to ", quoteIdent colNameNew, ";"]---- | Alters a column in the given table. For example,------ @---   change_column \"posts\" \"title\" \"DROP DEFAULT\"--- @------ drops the default constraint for the \"title\" column in the \"posts\"--- table.-change_column :: S8.ByteString-              -- ^ Table name-              -> S8.ByteString-              -- ^ Column name-              -> S8.ByteString-              -- ^ Action-              -> Migration Int64-change_column = ((executeQuery_ .) .) . change_column_stmt---- | Returns a 'Query' that alters a column in the given table. For example,------ @---   change_column \"posts\" \"title\" \"DROP DEFAULT\"--- @------ Returns the query------ @---   ALTER TABLE \"posts\" ALTER \"title\" DROP DEFAULT;--- @-change_column_stmt :: S8.ByteString-                   -- ^ Table name-                   -> S8.ByteString-                   -- ^ Column name-                   -> S8.ByteString-                   -- ^ Action-                   -> Query-change_column_stmt tableName colName action = Query $ S8.concat-  [ "alter table ", quoteIdent tableName, " alter "-  , quoteIdent colName, " ", action, ";"]--data CmdArgs = CmdArgs { cmd :: String-                       , cmdVersion :: String-                       , cmdCommit :: Bool }---- | Creates an index for efficient lookup.-create_index :: S8.ByteString-             -- ^ Index name-             -> S8.ByteString-             -- ^ Table name-             -> [S8.ByteString]-             -- ^ Column names-             -> Migration Int64-create_index = ((executeQuery_ .) .) . (create_index_stmt False)---- | Creates a unique index for efficient lookup.-create_unique_index :: S8.ByteString-                    -- ^ Index name-                    -> S8.ByteString-                    -- ^ Table name-                    -> [S8.ByteString]-                    -- ^ Column names-                    -> Migration Int64-create_unique_index = ((executeQuery_ .) .) . (create_index_stmt True)---- | Returns a 'Query' that creates an index for the given columns on the given--- table. For example,------ @---   create_index_stmt \"post_owner_index\" \"posts\" \"owner\"--- @------ Returns the query------ @---   CREATE INDEX \"post_owner_index\" ON \"posts\" (\"owner\")--- @-create_index_stmt :: Bool -                  -- ^ Unique index?-                  -> S8.ByteString-                  -- ^ Index name-                  -> S8.ByteString-                  -- ^ Table name-                  -> [S8.ByteString]-                  -- ^ Column names-                  -> Query-create_index_stmt unq indexName tableName colNames = Query $ S8.concat-  [ "create", unique, " index ", quoteIdent indexName, " on "-  , quoteIdent tableName, " (", cols, ")", ";" ]-  where cols = S8.intercalate ", " $ map quoteIdent colNames-        unique = if unq then " unique" else ""---- | Drops an index.-drop_index :: S8.ByteString-           -- ^ Index name-           -> Migration Int64-drop_index = executeQuery_ . drop_index_stmt---- | Returns a 'Query' that drops an index.------ @---   drop_index_stmt \"post_owner_index\"--- @------ Returns the query------ @---   DROP INDEX \"post_owner_index\"--- @-drop_index_stmt :: S8.ByteString-                -- ^ Index name-                -> Query-drop_index_stmt indexName = Query $ S8.concat-  [ "drop index ", quoteIdent indexName, ";" ]--parseCmdArgs :: [String] -> Maybe CmdArgs-parseCmdArgs args = do-  mycmd <- listToMaybe args-  let args0 = tail args-  myversion <- listToMaybe args0-  return $ go (CmdArgs mycmd myversion False) $ tail args0-  where go res [] = res-        go res (arg:as) =-          let newRes = case arg of-                        "--with-db-commit" -> res { cmdCommit = True }-                        _ -> res-          in go newRes as--defaultMain :: (Connection -> IO ()) -- ^ Migration function-            -> (Connection -> IO ()) -- ^ Rollback function-            -> IO ()-defaultMain up down = do-  (Just cmdArgs) <- getArgs >>= return . parseCmdArgs-  case cmd cmdArgs of-    "up" -> do-      conn <- connectEnv-      res <- query_ conn-          "select version from schema_migrations order by version desc limit 1"-      let currentVersion = case res of-                      [] -> ""-                      (Only v):_ -> v-      let version = cmdVersion cmdArgs-      if currentVersion < version then do-          begin conn-          up conn-          void $ execute conn "insert into schema_migrations values(?)"-                              (Only version)-          if cmdCommit cmdArgs then-            commit conn-            else rollback conn-        else exitWith $ ExitFailure 1-    "down" -> do-      conn <- connectEnv-      res <- query_ conn-          "select version from schema_migrations order by version desc limit 1"-      let currentVersion = case res of-                      [] -> ""-                      (Only v):_ -> v-      let version = cmdVersion cmdArgs-      if currentVersion == version then do-          begin conn-          down conn-          void $ execute conn "delete from schema_migrations where version = ?"-              (Only version)-          if cmdCommit cmdArgs then-            commit conn-            else rollback conn-        else-          exitWith $ ExitFailure 1-    _ -> exitWith $ ExitFailure 1-
− Database/PostgreSQL/ORM.hs 
@@ -1,29 +0,0 @@--module Database.PostgreSQL.ORM (-  -- * The Model class and related types-    Model(modelInfo, modelValid), ModelInfo(..)-  , defaultModelInfo, underscoreModelInfo-  , DBKey(..), DBRef, DBRefUnique, mkDBRef, primaryKey-  , (:.), As(..), RowAlias(..), fromAs-  -- ** Single-row operations-  , findRow, findAll, save, trySave, destroy, destroyByRef-  -- * Abstracted select queries-  , DBSelect(..), modelDBSelect, dbSelectParams, dbSelect-  , addWhere_, addWhere, setOrderBy, setLimit, setOffset-  -- * Associations between models-  , Association, assocSelect, assocProject, assocWhere, findAssoc-  -- ** Parent-child associations-  , GDBRefInfo(..), DBRefInfo, defaultDBRefInfo, dbrefAssocs, has, belongsTo-  -- ** Join table associations-  , JoinTable(..), defaultJoinTable, jtAssocs, jtAdd, jtRemove, jtRemoveByRef-  -- ** Chaining associations-  , nestAssoc, chainAssoc-  -- ** Validations-  , ValidationError(..), validate, validateNotEmpty, validationError-  ) where--import Database.PostgreSQL.ORM.Model-import Database.PostgreSQL.ORM.DBSelect-import Database.PostgreSQL.ORM.Association-import Database.PostgreSQL.ORM.Validations-import Database.PostgreSQL.Simple ((:.))
− Database/PostgreSQL/ORM/Association.hs 
@@ -1,543 +0,0 @@-{-# LANGUAGE CPP #-}-{-# LANGUAGE FlexibleContexts #-}-{-# LANGUAGE FlexibleInstances #-}-{-# LANGUAGE MultiParamTypeClasses #-}-{-# LANGUAGE OverloadedStrings #-}-{-# LANGUAGE ScopedTypeVariables #-}-{-# LANGUAGE TypeOperators #-}--module Database.PostgreSQL.ORM.Association (-    Association(..), assocProject, assocWhere, findAssoc-    -- * Associations based on parent-child relationships-  , GDBRefInfo(..), DBRefInfo, defaultDBRefInfo, dbrefAssocs, has, belongsTo-    -- * Join table Associations-  , JoinTable(..), defaultJoinTable, jtAssocs, joinTable-    -- ** Operations on join tables-  , jtAdd, jtRemove, jtRemoveByRef-    -- ** Semi-internal join table functions-  , jtAddStatement, jtRemoveStatement, jtParam-  , jtFlip, jtAssoc-    -- * Nested and chained associations-  , nestAssoc, chainAssoc-  ) where--#if __GLASGOW_HASKELL__ < 710-import Control.Applicative-#endif-import qualified Data.ByteString as S-import qualified Data.ByteString.Char8 as S8-import Data.List-import Data.Monoid-import Database.PostgreSQL.Simple-import Database.PostgreSQL.Simple.ToField-import Database.PostgreSQL.Simple.Types--import Data.GetField-import Database.PostgreSQL.Escape-import Database.PostgreSQL.ORM.DBSelect-import Database.PostgreSQL.ORM.Model----- | A data structure representing a relationship between a model @a@--- and a model @b@.  At a high level, an @Association a b@ tells you--- how to find rows of type @b@ given rows of type @a@.  More--- concretely, this boils down to being able to make two types of--- query.------  * You want to look up a bunch of @(a ':.' b)@s, filtering using---  predicates on both @a@ and @b@ (e.g., get a list of recent posts---  and their authors).  For this purpose, you can use 'assocSelect',---  which allows you to 'addWhere' predicates mentioning columns in---  both @a@ and @b@.------  * You already have an instance of type @a@, and want to find all---  the @b@s associated with it.  For that you use either 'assocWhere'---  or 'findAssoc' (which internally access fields 'assocSelectOnlyB',---  'assocWhereQuery', and 'assocWhereParam').  This type of query is---  strictly less general than the first one, but can be formulated in---  a more efficient way by extracting values directly from a concrete---  instance of @a@ without needing to touch table @a@ in the---  database.---  --- Note that an @Association@ is asymmetric.  It tells you how to get--- @b@s from @a@s, but not vice versa.  In practice, there will almost--- always be an association in the other direction, too.  Functions--- such as 'dbrefAssocs' and 'jtAssocs' therefore create an--- @Association@ and its inverse simultaneously, returning them as a--- pair.-data Association a b = Association {-    assocSelect :: !(DBSelect (a :. b))-    -- ^ General select returning all instances of @a@ and @b@ that-    -- match according to the association.-  , assocSelectOnlyB :: !(DBSelect b)-    -- ^ The right-hand side of the 'assocSelect' query.  This query-    -- makes no mention of type @a@ (but can be combined with the next-    -- two fields to form an optimized query).  You probably never-    -- want to use this directly, and should instead use either-    -- 'findAssoc' or 'assocWhere'.  Also note this is not useful for-    -- selecting all the @b@s in the relation; for that you should use-    -- 'assocProject'.-  , assocWhereQuery :: !Query-    -- ^ A @WHERE@ clause to find all the 'b's associated with a-    -- particular @a@.  This can often be done more efficiently than-    -- through 'assocSelect'.  The clause contains @\'?\'@ characters-    -- which should be filled in by 'assocWhereParam'.-  , assocWhereParam :: !(a -> [Action])-    -- ^ The query parameters for the query returned by-    -- 'assocWhereQuery'.-  }--instance Show (Association a b) where-  show assoc =-    "Association { assocSelect = " ++ show (assocSelect assoc) ++-    ", assocSelectOnlyB = " ++ show (assocSelectOnlyB assoc) ++-    ", assocWhereQuery = " ++ S8.unpack (fromQuery $ assocWhereQuery assoc) ++-    " }"---- | A projection of 'assocSelect', extracting only the fields of--- model @b@.  Note that this query touches table @a@ even if it does--- not return results from @a@.  Hence, you can use 'addWhere' to add--- predicates on both @a@ and @b@.  (Note the contrast to--- 'assocSelectOnlyB', which does not touch table @a@ at all, and--- hence in the case of an @INNER JOIN@ might return rows of @b@ that--- should not be part of the association.  'assocSelectOnlyB' is--- intended for use only in conjunction with 'assocWhereQuery'.)-assocProject :: (Model b) => Association a b -> DBSelect b-assocProject = dbProject . assocSelect---- | Returns a 'DBSelect' for all @b@s associated with a particular--- @a@.-assocWhere :: (Model b) => Association a b -> a -> DBSelect b-assocWhere ab a = addWhere (assocWhereQuery ab) (assocWhereParam ab a)-                  (assocSelectOnlyB ab)---- | Follow an association to return all of the @b@s associated--- with a particular @a@.  The behavior is similar to:------ > findAssoc' ab c a = dbSelect c $ assocWhere ab a------ But if the first argument is a static association, this function--- may be marginally faster because it pre-renders most of the query.-findAssoc :: (Model b) => Association a b -> Connection -> a -> IO [b]-{-# INLINE findAssoc #-}-findAssoc assoc = \c a ->-  map lookupRow <$> query c q (assocWhereParam assoc a)-  where {-# NOINLINE q #-}-        q = renderDBSelect $-            addWhere_ (assocWhereQuery assoc) $ assocSelectOnlyB assoc---- | Combine two associations into one.-nestAssoc :: (Model a, Model b) =>-             Association a b -> Association b c -> Association a (b :. c)-nestAssoc ab bc = ab { assocSelect = dbNest (assocSelect ab) (assocSelect bc)-                     , assocSelectOnlyB = assocSelect bc }---- | Combine two associations into one, and project away the middle--- type.  (The middle type can still be mentioned in @WHERE@ clauses.)------ An example:------ > data Author = Author {--- >     authorId :: DBKey--- >   } deriving (Show, Generic)--- > instance Model Author where modelInfo = underscoreModelInfo "author"--- > --- > data Post = Post {--- >     postId :: DBKey--- >   , postAuthorId :: DBRef Author--- >   } deriving (Show, Generic)--- > instance Model Post where modelInfo = underscoreModelInfo "post"--- > --- > data Comment = Comment {--- >     commentId :: DBKey--- >   , commentPostId :: DBRef Post--- >   } deriving (Show, Generic)--- > instance Model Comment where modelInfo = underscoreModelInfo "comment"--- > --- > author_posts :: Association Author Post--- > post_author :: Association Post Author--- > (post_author, author_posts) = dbrefAssocs defaultDBRefInfo--- > --- > -- Could equally well use dbrefAssocs as above--- > post_comments :: Association Post Comment--- > post_comments = has--- >--- > comment_post :: Association Comment Post--- > comment_post = belongsTo--- > --- > comment_author :: Association Comment Author--- > comment_author = chainAssoc comment_post post_author--- > --- > author_comments :: Association Author Comment--- > author_comments =  chainAssoc author_posts post_comments-chainAssoc :: (Model a, Model b, Model c) =>-              Association a b -> Association b c -> Association a c-chainAssoc ab bc = ab { assocSelect = dbChain (assocSelect ab) (assocSelect bc)-                      , assocSelectOnlyB = dbProject $ assocSelect bc }----- | A common type of association is when one model contains a 'DBRef'--- or 'DBRefUnique' pointing to another model.  In this case, the--- model containing the 'DBRef' is known as the /child/, and the--- referenced model is known as the /parent/.------ Two pieces of information are required to describe a parent-child--- relationship:  First, the field selector that extracts the Haskell--- 'DBRef' from the haskell type @child@, and second the name of the--- database column that stores this 'DBRef' field.------ For example, consider the following:------ > data Author = Author {--- >     authorId :: DBKey--- >   } deriving (Show, Generic)--- > instance Model Author--- > --- > data Post = Post {--- >     postId :: DBKey--- >   , postAuthorId :: DBRef Author--- >   } deriving (Show, Generic)--- > instance Model Post--- >--- > post_author_refinfo :: DBRefInfo Post Author--- > post_author_refinfo = DBRefInfo {--- >     dbrefSelector = postAuthorId--- >   , dbrefQColumn = "\"post\".\"postAuthorId\""--- >   }------ Note that the parent-child relationship described by a @GDBRefInfo@--- is asymmetric, but bidirectional.  When a @'DBRefInfo' child--- parent@ exists, the schema should generally /not/ permit the--- existence of a valid @'DBRefInfo' parent child@ structure.--- However, the 'dbrefAssocs' function generates 'Association's in--- both directions from a single 'DBRefInfo'.------ Constructing such parent-child 'Association's requires knowing how--- to extract primary keys from the @parent@ type as well as the name--- of the column storing primary keys in @parent@.  Fortunately, this--- information is already available from the 'Model' class, and thus--- does not need to be in the @GDBRefInfo@.  (Most functions on--- @GDBRefInfo@s require @parent@ and @child@ to be instances of--- 'Model'.)------ When your 'Model's are instances of 'Generic' (which will usually--- be the case), a 'DBRefInfo' structure can be computed automatically--- by 'defaultDBRefInfo'.  This is the recommended way to produce a--- @GDBRefInfo@.  (Alternatively, see 'has' and 'belongsTo' to make--- use of an entirely implicit @DBRefInfo@.)-data GDBRefInfo reftype child parent = DBRefInfo {-    dbrefSelector :: !(child -> GDBRef reftype parent)-    -- ^ Field selector returning a reference.-  , dbrefQColumn :: !S.ByteString-    -- ^ Literal SQL for the database column storing the reference.-    -- This should be double-quoted and table-qualified, in case the-    -- column name is a reserved keyword, contains capital letters, or-    -- conflicts with the name of a column in the joined table.  An-    -- example would be:-    ---    -- > dbrefQColumn = "\"table_name\".\"column_name\""-  }--instance Show (GDBRefInfo rt c p) where-  show ri = "DBRefInfo ? " ++ show (dbrefQColumn ri)---- | @DBRefInfo@ is a type alias for the common case that the--- reference in a 'GDBRefInfo' is a 'DBRef' (as opposed to a--- 'DBRefUnique').  The functions in this library do not care what--- type of reference is used.  The type is generalized to 'GDBRefInfo'--- just to make it easier to assign a selector to 'dbrefSelector' when--- the selector returns a 'DBRefUnique'.  Note, however, that--- 'defaultDBRefInfo' returns a 'DBRefInfo' regardless of the flavor--- of reference actually encountered.-type DBRefInfo = GDBRefInfo NormalRef--data ExtractRef a = ExtractRef deriving (Show)-instance Extractor ExtractRef (GDBRef rt a) (DBRef a) THasOne where-  extract _ (DBRef k) = THasOne $ DBRef k-instance Extractor ExtractRef (GDBRef rt a) (DBRef (As alias a)) THasOne where-  extract _ (DBRef k) = THasOne $ DBRef k-instance Extractor ExtractRef (Maybe (GDBRef rt a)) (DBRef a) THasOne where-  extract _ (Just (DBRef k)) = THasOne $ DBRef k-  extract _ _                = error "Maybe DBRef is Nothing"-instance Extractor ExtractRef (Maybe (GDBRef rt a)) (DBRef (As alias a))-         THasOne where-  extract _ (Just (DBRef k)) = THasOne $ DBRef k-  extract _ _                = error "Maybe DBRef is Nothing"---- | Creates a 'DBRefInfo' from a model @child@ that references--- @parent@.  For this to work, the @child@ type must be an instance--- of 'Generic' and must contain exactly one field of the any of the--- following types:------   1. @'GDBRef' rt parent@, which matches both @'DBRef' parent@ and---   @'DBRefUnique' parent@.------   2. @Maybe ('GDBRef' rt parent)@, for cases where the reference---   might be @NULL@.  Note, however, that an exception will be thrown---   if you call 'findAssoc' on a child whose reference is 'Nothing'.------ A special case arises when a Model contains a 'DBRef' to itself.--- If you just wish to find parents and children given an existing--- structure (i.e., 'findAssoc'), it is okay to declare an--- @'Association' MyType MyType@.  However, in this case attempts to--- use 'assocSelect' will then fail.  To work around this problem, the--- parent must use a row alias.------ Note that currently /aliasing the child will not work/, since the--- 'As' data structure will not contain a 'DBRef' field, only the--- contents of the 'As' data structure.  An example of doing this--- correctly (using 'has' and 'belongsTo', both of which wrap--- @defaultDBRefInfo@):------ > data Bar = Bar {--- >     barId :: !DBKey--- >   , barName :: !String--- >   , barParent :: !(Maybe (DBRef Bar))--- >   } deriving (Show, Generic)--- > instance Model Bar where modelInfo = underscoreModelInfo "bar"--- > --- > data ParentBar = ParentBar--- > instance RowAlias ParentBar where rowAliasName _ = "parent_bar"--- > --- > toParent :: Association Bar (As ParentBar Bar)--- > toParent = belongsTo--- > --- > toChild :: Association (As ParentBar Bar) Bar--- > toChild = has-defaultDBRefInfo :: forall child parent.-                    (Model child, Model parent-                    , GetField ExtractRef child (DBRef parent)) =>-                    DBRefInfo child parent-defaultDBRefInfo = ri-  where extractor = (const ExtractRef :: g p -> ExtractRef (DBRef p)) ri-        child = undefined :: child-        childids = modelIdentifiers :: ModelIdentifiers child-        ri = DBRefInfo {-            dbrefSelector = getFieldVal extractor-          , dbrefQColumn = modelQColumns childids !! getFieldPos extractor child-          }---- | Generate both the child-parent and parent-child 'Association's--- implied by a 'GDBRefInfo'.-dbrefAssocs :: forall child parent rt.-               (Model child, Model parent) =>-               GDBRefInfo rt child parent-               -> (Association child parent, Association parent child)-dbrefAssocs ri = (c_p, p_c)-  where idp = modelIdentifiers :: ModelIdentifiers parent-        on = Query $ "ON " <> modelQPrimaryColumn idp-             <> " = " <> dbrefQColumn ri-        c_p = Association {-            assocSelect = dbJoinModels "JOIN" on-          , assocSelectOnlyB = modelDBSelect-          , assocWhereQuery = Query $ modelQPrimaryColumn idp <> " = ?"-          , assocWhereParam = \child -> [toField $ dbrefSelector ri child]-          }-        p_c = Association {-            assocSelect = dbJoinModels "JOIN" on-          , assocSelectOnlyB = modelDBSelect-          , assocWhereQuery = Query $ dbrefQColumn ri <> " = ?"-          , assocWhereParam = \parent -> [toField $ primaryKey parent]-          }----- | Short for------ > snd $ dbrefAssocs defaultDBRefInfo------ Note the inverse 'Association' is given by 'belongsTo'.  For--- example, given the @Author@ and @Post@ models described in the--- documentation for 'GDBRefInfo', in which each @Post@ references an--- @Author@, you might say:------ > author_post :: Association Author Post--- > author_post = has--- >--- > post_author :: Association Post Author--- > post_author = belongsTo-has :: (Model child, Model parent, GetField ExtractRef child (DBRef parent)) =>-       Association parent child-has = snd $ dbrefAssocs defaultDBRefInfo---- | The inverse of 'has'.  Short for------ > fst $ dbrefAssocs defaultDBRefInfo------ See an example at 'has'.-belongsTo :: (Model child, Model parent-             , GetField ExtractRef child (DBRef parent)) =>-             Association child parent-belongsTo = fst $ dbrefAssocs defaultDBRefInfo---- | A data structure representing a dedicated join table in the--- database.  A join table differs from a model in that rows do not--- have primary keys.  Hence, model operations do not apply.--- Nonetheless a join table conveys information about a relationship--- between models.------ Note that all names in a @JoinTable@ should be unquoted.-data JoinTable a b = JoinTable {-    jtTable :: !S.ByteString-    -- ^ Name of the join table in the database.  (Not quoted.)-  , jtColumnA :: !S.ByteString-    -- ^ Name of the column in table 'jtTable' that contains a 'DBRef'-    -- to model @a@.  (Not quoted or table-qualified.)-  , jtColumnB :: !S.ByteString-    -- ^ Like 'jtColumnA' for model @b@.-  } deriving (Show)---- | The default join table has the following fields:------ * 'jtName' is the name of the two models (in alphabetical order),--- separated by an @\'_\'@ character.------ * 'jtColumnA' is the name of model @a@, an @\'_\'@ character, and--- the name of the primary key column in table @a@.------ * 'jtColumnB' is the name of model @b@, an @\'_\'@ character, and--- the name of the primary key column in table @b@.------ Note that 'defaultJoinTable' cannot create a default join table for--- joining a model to itself, as following these rules the two columns--- would have the same name.  If you wish to join a table to itself,--- you have two options:  First, you can define the join table and--- assign the column names manually.  This will permit you to call--- 'findAssoc', but you still will not be able to use 'assocSelect'--- for more complex queries, since SQL does not permit joins between--- two tables with the same name.  The second option is to give one of--- the sides of the join table a row alias with 'As'.  For example:------ > data ParentBar = ParentBar--- > instance RowAlias ParentBar where rowAliasName _ = "parent_bar"--- > --- > selfJoinTable :: JoinTable Bar (As ParentBar Bar)--- > selfJoinTable = defaultJoinTable--- > --- > selfJoin :: Association Bar (As ParentBar Bar)--- > otherSelfJoin :: Association (As ParentBar Bar) Bar--- > (selfJoin, otherSelfJoin) = jtAssocs selfJoinTable-defaultJoinTable :: forall a b. (Model a, Model b) => JoinTable a b-defaultJoinTable-  | colA == colB = error "defaultJoinTable has default for self joins"-  | otherwise = jti-  where a = modelInfo :: ModelInfo a-        b = modelInfo :: ModelInfo b-        colA = S.intercalate "_"-               [modelTable a, modelColumns a !! modelPrimaryColumn a]-        colB = S.intercalate "_"-               [modelTable b, modelColumns b !! modelPrimaryColumn b]-        jti = JoinTable {-            jtTable = S.intercalate "_" $ sort [modelTable a, modelTable b]-          , jtColumnA = colA-          , jtColumnB = colB-          }--jtQTable :: JoinTable a b -> S.ByteString-jtQTable = quoteIdent . jtTable--jtQColumnA :: JoinTable a b -> S.ByteString-jtQColumnA jt = S.concat [ jtQTable jt, ".", quoteIdent $ jtColumnA jt]--jtQColumnB :: JoinTable a b -> S.ByteString-jtQColumnB jt = S.concat [ jtQTable jt, ".", quoteIdent $ jtColumnB jt]---- | Flip a join table.  This doesn't change the name of the table--- (since the same join table is used in both directions, and the--- default join table name glues together the two model names in--- alphabetical order anyway).-jtFlip :: JoinTable a b -> JoinTable b a-jtFlip jt = jt { jtColumnA = jtColumnB jt , jtColumnB = jtColumnA jt }---- | A SQL statement suitable for adding a pair to a join table.  Note--- that the statement takes two parameters (i.e., contains two @\'?\'@--- characters) corresponding to the primary keys of the two models--- being associated.  These parameters can be supplied by 'jtParam'.-jtAddStatement :: JoinTable a b -> Query-jtAddStatement jt = Query $ S.concat [-    "INSERT INTO ", jtQTable jt, " ("-  , quoteIdent $ jtColumnA jt, ", ", quoteIdent $ jtColumnB jt-  , ") VALUES (?, ?) EXCEPT SELECT "-  , jtQColumnA jt, ", ", jtQColumnB jt, " FROM ", quoteIdent $ jtTable jt-  ]---- | Add an association between two models to a join table.  Returns--- 'True' if the association was not already there.-jtAdd :: (Model a, Model b) => JoinTable a b -> Connection -> a -> b -> IO Bool-{-# INLINE jtAdd #-}-jtAdd jt = \c a b -> (/= 0) <$> execute c q (jtParam jt a b)-  where {-# NOINLINE q #-}-        q = jtAddStatement jt---- | A SQL statement for removing a pair from a join table.  Like--- 'jtAddStatement', the query is parameterized by two primary keys.-jtRemoveStatement :: JoinTable a b -> Query-jtRemoveStatement jt = Query $ S.concat [-    "DELETE FROM ", quoteIdent $ jtTable jt, " WHERE "-  , jtQColumnA jt, " = ? AND ", jtQColumnB jt, " = ?"-  ]---- | Remove an association from a join table.  Returns 'True' if the--- association was previously there.-jtRemove :: (Model a, Model b) =>-            JoinTable a b -> Connection -> a -> b -> IO Bool-{-# INLINE jtRemove #-}-jtRemove jt = \c a b -> (/= 0) <$> execute c q (jtParam jt a b)-  where {-# NOINLINE q #-}-        q = jtRemoveStatement jt---- | Remove an assocation from a join table when you don't have the--- target instances of the two models handy, but do have references.-jtRemoveByRef :: (Model a, Model b) => JoinTable a b-                 -> Connection -> GDBRef rt a -> GDBRef rt b -> IO Bool-{-# INLINE jtRemoveByRef #-}-jtRemoveByRef jt = \c a b -> (/= 0) <$> execute c q (a, b)-  where {-# NOINLINE q #-}-        q = jtRemoveStatement jt---- | Generate parameters for 'jtAddStatement' and 'jtRemoveStatement'.--- The returned list is suitable for use as a 'ToRow' instance.  For--- example:------ > execute conn (jtAddStatement my_join_table) (jtParam a b)-jtParam :: (Model a, Model b) => JoinTable a b -> a -> b -> [Action]-jtParam _ a b = [toField $ primaryKey a, toField $ primaryKey b]---- | Generate a one-way association from a 'JoinTable'.  Use--- 'jtAssocs' instead.-jtAssoc :: forall a b. (Model a, Model b) => JoinTable a b -> Association a b-jtAssoc jt = Association {-    assocSelect = dbJoin modelDBSelect "JOIN" onlyB $ Query $ S.concat [-       "ON ", priA, " = ", jtQColumnA jt]-  , assocSelectOnlyB = onlyB-  , assocWhereQuery = Query $ jtQColumnA jt <> " = ?"-  , assocWhereParam = \a -> [toField $ primaryKey a]-  }-  where priA = modelQPrimaryColumn (modelIdentifiers :: ModelIdentifiers a)-        priB = modelQPrimaryColumn (modelIdentifiers :: ModelIdentifiers b)-        selB = modelDBSelect :: DBSelect b-        fromB = FromJoin-                (FromModel (Query $ jtQTable jt) (jtQTable jt))-                "JOIN" (selFrom selB)-                (Query $ S.concat ["ON ", jtQColumnB jt, " = ", priB])-                (jtQTable jt <> "->B")-        onlyB = selB { selFrom = fromB }---- | Generate the two associations implied by a 'JoinTable'.-jtAssocs :: (Model a, Model b) =>-            JoinTable a b -> (Association a b, Association b a)-jtAssocs jt = (jtAssoc jt, jtAssoc $ jtFlip jt)---- | Generate a one-way association based on the default join table--- naming scheme described at 'defaultJoinTable'.  Defined as:------ > joinTable = jtAssoc defaultJoinTable------ For example:------ > aToB :: Association A B--- > aToB = joinTable--- >--- > bToA :: Association B A--- > bToA = joinTable-joinTable :: (Model a, Model b) => Association a b-joinTable = jtAssoc defaultJoinTable
− Database/PostgreSQL/ORM/CreateTable.hs 
@@ -1,104 +0,0 @@-{-# LANGUAGE FlexibleContexts #-}-{-# LANGUAGE ScopedTypeVariables #-}-{-# LANGUAGE TypeOperators #-}-{-# LANGUAGE OverloadedStrings #-}---- | Functions for creating a table from a model.  These are mostly--- useful in development, for very rigid applications, or to compare--- what would be created against what is actually in the database.  In--- practice, production settings should create and update tables using--- migrations.------ Note that often it is more interesting to see what would be created--- than to create an actual table.  For that reason, functions--- creating the statements are exposed.-module Database.PostgreSQL.ORM.CreateTable (-  modelCreateStatement, modelCreate, GDefTypes(..)-  , jtCreateStatement, jtCreate-  ) where--import qualified Data.ByteString as S-import qualified Data.ByteString.Char8 as S8-import Data.Int-import Data.List-import Data.Monoid-import Database.PostgreSQL.Simple-import Database.PostgreSQL.Simple.Types-import GHC.Generics--import Database.PostgreSQL.ORM.Model-import Database.PostgreSQL.ORM.Association-import Database.PostgreSQL.ORM.SqlType---- | This is a helper class used to extract the row types.  You don't--- need to use this class.  If you are creating custom types, just--- declare an instance of 'SqlType'.-class GDefTypes f where-  gDefTypes :: f p -> [S.ByteString]-instance (SqlType c) => GDefTypes (K1 i c) where-  gDefTypes ~(K1 c) = [sqlType c]-instance (GDefTypes a, GDefTypes b) => GDefTypes (a :*: b) where-  gDefTypes ~(a :*: b) = gDefTypes a ++ gDefTypes b-instance (GDefTypes f) => GDefTypes (M1 i c f) where-  gDefTypes ~(M1 fp) = gDefTypes fp--customModelCreateStatement :: forall a.-  (Model a, Generic a, GDefTypes (Rep a)) =>-  [(S.ByteString, S.ByteString)]-  -- ^ A list of @(@/field/@,@/type/@)@ pairs to overwrite the default-  -- SQL types of fields.-  -> [S.ByteString]-  -- ^ A list of extra table constraints.-  -> a-  -- ^ A non-strict argument to specify which model's table you want-  -- to create.  @(undefined :: YourModel)@ should be fine.-  -> Query-customModelCreateStatement except constraints a-  | not (null extraneous) =-    error $ "customCreateTableStatement: no such columns: " ++ show extraneous-  | otherwise = Query $ S.concat [-  "CREATE TABLE ", quoteIdent $ modelTable info, " ("-  , S.intercalate ", " (go types names)-  , S.concat $ concatMap (\c -> [", ", c]) constraints, ")"-  ]-  where extraneous = fst (unzip except) \\ names-        types = gDefTypes $ from a-        info = modelInfo :: ModelInfo a-        names = modelColumns info-        go (t:ts) (n:ns)-          | Just t' <- lookup n except = quoteIdent n <> " " <> t' : go ts ns-          | otherwise = quoteIdent n <> " " <> t : go ts ns-        go [] [] = []-        go _ _ = error $ "createTable: " ++ S8.unpack (modelTable info) ++-                 " has incorrect number of columns"---- | Statement for creating the table corresponding to a model.  Not--- strict in its argument.-modelCreateStatement :: forall a. (Model a, Generic a, GDefTypes (Rep a))-                     => a -> Query-modelCreateStatement a = customModelCreateStatement except constraints a-  where ModelCreateInfo except constraint = modelCreateInfo :: ModelCreateInfo a-        constraints = if S.null constraint then [] else [constraint]---- | Create a the database table for a model.-modelCreate :: (Model a, Generic a, GDefTypes (Rep a)) =>-               Connection -> a -> IO Int64-modelCreate c a = execute_ c (modelCreateStatement a)---- | Create the database table corresponding to a 'JoinTable'.-jtCreateStatement :: (Model a, Model b) => JoinTable a b -> Query-jtCreateStatement jt = Query $ S.concat [-    "CREATE TABLE ", quoteIdent $ jtTable jt, " ("-    , S.intercalate ", " $ sort [typa, typb]-    , ", UNIQUE (", S.intercalate ", " $ sort [ida, idb], "))"-  ]-  where ida = quoteIdent $ jtColumnA jt-        idb = quoteIdent $ jtColumnB jt-        refa = (undefined :: JoinTable a b -> DBRef a) jt-        refb = (undefined :: JoinTable a b -> DBRef b) jt-        typa = ida <> " " <> sqlBaseType refa <> " ON DELETE CASCADE NOT NULL"-        typb = idb <> " " <> sqlBaseType refb <> " ON DELETE CASCADE NOT NULL"---- | Create a join table in the database.-jtCreate :: (Model a, Model b) => Connection -> JoinTable a b -> IO Int64-jtCreate c jt = execute_ c (jtCreateStatement jt)
− Database/PostgreSQL/ORM/DBSelect.hs 
@@ -1,473 +0,0 @@-{-# LANGUAGE Trustworthy #-}-{-# LANGUAGE CPP #-}-{-# LANGUAGE DeriveGeneric #-}-{-# LANGUAGE FlexibleInstances #-}-{-# LANGUAGE OverloadedStrings #-}-{-# LANGUAGE ScopedTypeVariables #-}-{-# LANGUAGE TypeOperators #-}-{-# LANGUAGE RecordWildCards #-}--module Database.PostgreSQL.ORM.DBSelect (-    -- * The DBSelect structure-    DBSelect(..), FromClause(..)-    -- * Executing DBSelects-  , dbSelectParams, dbSelect-  , Cursor(..), curSelect, curNext-  , dbFold, dbFoldM, dbFoldM_-  , dbCollect-  , renderDBSelect, buildDBSelect-    -- * Creating DBSelects-  , emptyDBSelect, expressionDBSelect-  , modelDBSelect-  , dbJoin, dbJoinModels-  , dbProject, dbProject'-  , dbNest, dbChain-    -- * Altering DBSelects-  , addWhere_, addWhere, setOrderBy, setLimit, setOffset, addExpression-  ) where--import Control.Monad.IO.Class-import Blaze.ByteString.Builder-import Blaze.ByteString.Builder.Char.Utf8 (fromChar)-import qualified Data.ByteString as S-import qualified Data.ByteString.Char8 as S8-#if __GLASGOW_HASKELL__ < 710-import Data.Functor-#endif-import Data.Monoid-import Data.String-import Data.IORef-import Database.PostgreSQL.Simple-import Database.PostgreSQL.Simple.Internal-import Database.PostgreSQL.Simple.Types-import GHC.Generics--import Database.PostgreSQL.Escape-import Database.PostgreSQL.ORM.Model---- | As it's name would suggest, a @FromClause@ is the part of a query--- between the @FROM@ keyword and the @WHERE@ keyword.  It can consist--- of simple table names, @JOIN@ operations, and parenthesized--- subqueries.------ From clauses are represented in a more structured way than the--- other fields so as to allow the possibility of collapsing join--- relations.  For instance, given a @'DBSelect' (A :. B)@ and a--- @'DBSelect' (B :. C)@, it is desirable to be able to generate a--- @'DBSelect' (A :. B :. C)@ in which each pair of terms involving--- @B@ in the three-way relation is constrained according to the--- original two queries.  This functionality is provided by 'dbNest'--- and 'dbChain', but it requires the ability to locate and replace--- the instance of type @B@ in one 'DBSelect' with the @FromClause@ of--- the other 'DBSelect'.------ The 'fcCanonical' field is a canonical name of each type, which by--- convention is the quoted and fully-qualified table name.  Comparing--- 'fcCanonical' is somewhat of a hack, and happens entirely at--- runtime.  It would be nicer to do this at compile time, but doing--- so would require language extensions such as @GADTs@ of--- @FunctionalDependencies@.-data FromClause = FromModel {-    fcVerbatim :: !Query -- ^ Verbatim SQL for a table, table @AS@-                         -- alias, or parenthesized subquery.-  , fcCanonical :: !S.ByteString-    -- ^ Canonical name of the table or join relation represented by-    -- this term.  For @JOIN@ terms, this is always the @CROSS JOIN@-    -- of the canonical names of 'fcLeft' and 'fcRight'.  This means-    -- one can locate a join given only it's type (e.g., the canonical-    -- name for @A :. B@ is always @\"a CROSS JOIN b\"@), but it does-    -- mean you have to be careful not accidentally to merge two-    -- different joins on the same types.  For this reason it may be-    -- safest always to have type @b@ be a single table in 'dbNest'-    -- and 'dbChain'.-  }-  | FromJoin {-    fcLeft :: !FromClause-  , fcJoinOp :: !Query -- ^ Usually @\"JOIN\"@-  , fcRight :: !FromClause-  , fcOnClause :: !Query -- ^ @ON@ or @USING@ clause (or empty)-  , fcCanonical :: !S.ByteString-  }-  deriving Show--nullFrom :: FromClause -> Bool-nullFrom (FromModel q _) | qNull q = True-nullFrom _                         = False---- | A deconstructed SQL select statement that allows easier--- manipulation of individual terms.  Several functions are provided--- to combine the 'selFields', 'selFrom', and 'selWhere' clauses of--- muliple @DBSelect@ structures.  Other clauses may be discarded when--- combining queries with join operations.  Hence it is advisable to--- set the other clauses at the end (or, if you set these fields, to--- collapse your 'DBSelect' structure into a subquery using--- `dbProject'`).-data DBSelect a = DBSelect {-    selWith :: !Query-  , selSelectKeyword :: !Query-    -- ^ By default @\"SELECT\"@, but might usefully be set to-    -- something else such as @\"SELECT DISTINCT\"@ in some-    -- situations.-  , selFields :: Query-  , selFrom :: !FromClause-  , selWhereKeyword :: !Query-    -- ^ Empty by default, but set to @\"WHERE\"@ if any @WHERE@-    -- clauses are added to the 'selWhere' field.-  , selWhere :: !Query-  , selGroupBy :: !Query-  , selHaving :: !Query-    -- below here, should appear outside any union-  , selOrderBy :: !Query-  , selLimit :: !Query-  , selOffset :: !Query-  } deriving (Generic)--instance Show (DBSelect a) where-  show = S8.unpack . fromQuery . renderDBSelect--space :: Builder-space = fromChar ' '--qNull :: Query -> Bool-qNull = S.null . fromQuery--qBuilder :: Query -> Builder-qBuilder = fromByteString . fromQuery--toQuery :: Builder -> Query-toQuery = Query . toByteString--buildFromClause :: FromClause -> Builder-buildFromClause (FromModel q _) | qNull q = mempty-buildFromClause cl0 = fromByteString " FROM " <> go cl0-  where go (FromModel q _) = qBuilder q-        go (FromJoin left joinkw right onClause _) = mconcat [-            fromChar '(', go left, space, qBuilder joinkw, space, go right-          , if qNull onClause then mempty else space <> qBuilder onClause-          , fromChar ')' ]--class GDBS f where-  gdbsDefault :: f p-  gdbsQuery :: f p -> Builder-instance GDBS (K1 i Query) where-  gdbsDefault = K1 (Query S.empty)-  gdbsQuery (K1 q) | qNull q = mempty-                   | otherwise = space <> qBuilder q-instance GDBS (K1 i FromClause) where-  gdbsDefault = K1 (FromModel "" "")-  gdbsQuery (K1 fc) = buildFromClause fc-instance (GDBS a, GDBS b) => GDBS (a :*: b) where-  gdbsDefault = gdbsDefault :*: gdbsDefault-  gdbsQuery (a :*: b) = gdbsQuery a <> gdbsQuery b-instance (GDBS f) => GDBS (M1 i c f) where-  gdbsDefault = M1 gdbsDefault-  gdbsQuery = gdbsQuery . unM1---- | A 'DBSelect' structure with keyword @\"SELECT\"@ and everything--- else empty.-emptyDBSelect :: DBSelect a-emptyDBSelect = (to gdbsDefault) { selSelectKeyword = fromString "SELECT" }---- | A 'DBSelect' for one or more comma-separated expressions, rather--- than for a table.  For example, to issue the query @\"SELECT--- lastval()\"@:------ > lastval :: DBSelect (Only DBKeyType)--- > lastval = expressionDBSelect "lastval ()"--- >--- >   ...--- >   [just_inserted_id] <- dbSelect conn lastval------ On the other hand, for such a simple expression, you might as well--- call 'query_' directly.-expressionDBSelect :: (Model r) => Query -> DBSelect r-expressionDBSelect q = emptyDBSelect { selFields = q }---- | Create a 'Builder' for a rendered version of a 'DBSelect'.  This--- can save one string copy if you want to embed one query inside--- another as a subquery, as done by `dbProject'`, and thus need to--- parenthesize it.  However, the function is probably not a useful--- for end users.-buildDBSelect :: DBSelect a -> Builder-buildDBSelect dbs = gdbsQuery $ from dbs---- | Turn a 'DBSelect' into a 'Query' suitable for the 'query' or--- 'query_' functions.-renderDBSelect :: DBSelect a -> Query-renderDBSelect = Query . S.tail . toByteString . buildDBSelect--- S.tail is because the rendering inserts an extra space at the beginning--catQueries :: Query -> Query -> Query -> Query-catQueries left delim right-  | qNull left  = right-  | qNull right = left-  | otherwise   = Query $ S.concat $ map fromQuery [left, delim, right]---- | Add a where clause verbatim to a 'DBSelect'.  The clause must--- /not/ contain the @WHERE@ keyword (which is added automatically by--- @addWhere_@ if needed).  If the @DBSelect@ has existing @WHERE@--- clauses, the new clause is appended with @AND@.  If the query--- contains any @\'?\'@ characters, they will be rendered into the--- query and matching parameters will later have to be filled in via a--- call to 'dbSelectParams'.-addWhere_ :: Query -> DBSelect a -> DBSelect a-addWhere_ q dbs-  | qNull q = dbs-  | otherwise = dbs { selWhereKeyword = "WHERE"-                    , selWhere = catQueries (selWhere dbs) " AND " q }---- | Add a where clause, and pre-render parameters directly into the--- clause.  The argument @p@ must have exactly as many fields as there--- are @\'?\'@ characters in the 'Query'.  Example:------ > bars <- dbSelect c $ addWhere "bar_id = ?" (Only target_id) $--- >                      (modelDBSelect :: DBSelect Bar)-addWhere :: (ToRow p) => Query -> p -> DBSelect a -> DBSelect a-addWhere q p dbs-  | qNull q = dbs-  | otherwise = dbs {-    selWhereKeyword = "WHERE"-  , selWhere = if qNull $ selWhere dbs-               then toQuery clause-               else toQuery $ qBuilder (selWhere dbs) <>-                    fromByteString " AND " <> clause-  }-  where clause = mconcat [fromChar '(', buildSql q p, fromChar ')']---- | Set the @ORDER BY@ clause of a 'DBSelect'.  Example:------ > dbSelect c $ setOrderBy "\"employeeName\" DESC NULLS FIRST" $--- >                modelDBSelect-setOrderBy :: Query -> DBSelect a -> DBSelect a-setOrderBy (Query ob) dbs = dbs { selOrderBy = Query $ "ORDER BY " <> ob }---- | Set the @LIMIT@ clause of a 'DBSelect'.-setLimit :: Int -> DBSelect a -> DBSelect a-setLimit i dbs = dbs { selLimit = fmtSql "LIMIT ?" (Only i) }---- | Set the @OFFSET@ clause of a 'DBSelect'.-setOffset :: Int -> DBSelect a -> DBSelect a-setOffset i dbs = dbs { selOffset = fmtSql "OFFSET ?" (Only i) }---- | Add one or more comma-separated expressions to 'selFields' that--- produce column values without any corresponding relation in the--- @FROM@ clause.  Type @r@ is the type into which the expression is--- to be parsed.  Generally this will be an instance of 'FromRow' that--- is a degenerate model (e.g., 'Only', or a tuple).------ For example, to rank results by the field @value@ and compute the--- fraction of overall value they contribute:------ > r <- dbSelect c $ addExpression--- >        "rank() OVER (ORDER BY value), value::float4/SUM(value) OVER ()"--- >        modelDBSelect--- >          :: IO [Bar :. (Int, Double)]-addExpression :: (Model r) => Query -> DBSelect a -> DBSelect (a :. r)-addExpression q dbs = dbs {-  selFields = if qNull $ selFields dbs then q-              else Query $ S.concat $ map fromQuery [selFields dbs, ", ", q]-  }---- | A 'DBSelect' that returns all rows of a model.-modelDBSelect :: forall a. (Model a) => DBSelect a-modelDBSelect = r-  where mi = modelIdentifiers :: ModelIdentifiers a-        r = emptyDBSelect {-          selFields = Query $ S.intercalate ", " $ modelQColumns mi-          , selFrom = FromModel (Query $ modelQTable mi) (modelQTable mi)-          }---- | Run a 'DBSelect' query on parameters.  The number of @\'?\'@--- characters embedeed in various fields of the 'DBSelect' must--- exactly match the number of fields in parameter type @p@.  Note the--- order of arguments is such that the 'DBSelect' can be pre-rendered--- and the parameters supplied later.  Hence, you should use this--- version when the 'DBSelect' is static.  For dynamically modified--- 'DBSelect' structures, you may prefer 'dbSelect'.-dbSelectParams :: (Model a, ToRow p) => DBSelect a -> Connection -> p -> IO [a]-{-# INLINE dbSelectParams #-}-dbSelectParams dbs = \c p -> map lookupRow <$> query c q p-  where -- {-# NOINLINE q #-} (crashes under GHC 7.8)-        q = renderDBSelect dbs---- | Run a 'DBSelect' query and return the resulting models.-dbSelect :: (Model a) => Connection -> DBSelect a -> IO [a]-{-# INLINE dbSelect #-}-dbSelect c dbs = map lookupRow <$> query_ c q-  where -- {-# NOINLINE q #-} (crashes under GHC 7.8)-        q = renderDBSelect dbs---- | Datatype that represents a connected cursor-data Cursor a = Cursor { curConn :: !Connection-                       , curName :: !Query-                       , curChunkSize :: !Query-                       , curCache :: IORef [a] }---- | Create a 'Cursor' for the given 'DBSelect'-curSelect :: Model a => Connection -> DBSelect a -> IO (Cursor a)-curSelect c dbs = do-  name <- newTempName c-  execute_ c $-    mconcat [ "DECLARE ", name, " NO SCROLL CURSOR FOR ", q ]-  cacheRef <- newIORef []-  return $ Cursor c name "256" cacheRef-  where q = renderDBSelect dbs---- | Fetch the next 'Model' for the underlying 'Cursor'. If the cache has--- prefetched values, dbNext will return the head of the cache without querying--- the database. Otherwise, it will prefetch the next 256 values, return the--- first, and store the rest in the cache.-curNext :: Model a => Cursor a -> IO (Maybe a)-curNext Cursor{..} = do-  cache <- readIORef curCache-  case cache of-    x:xs -> do-      writeIORef curCache xs-      return $ Just x-    [] -> do-      res <- map lookupRow <$> query_ curConn (mconcat-              [ "FETCH FORWARD ", curChunkSize, " FROM ", curName])-      case res of-        [] -> return Nothing-        x:xs -> do-          writeIORef curCache xs-          return $ Just x---- | Streams results of a 'DBSelect' and consumes them using a left-fold. Uses--- default settings for 'Cursor' (batch size is 256 rows).-dbFold :: Model model-       => Connection -> (b -> model -> b) -> b -> DBSelect model -> IO b-dbFold c act initial dbs = do-  cur <- curSelect c dbs-  go cur initial-  where go cur accm = do-          mres <- curNext cur-          case mres of-            Nothing -> return accm-            Just res -> go cur (act accm res)---- | Streams results of a 'DBSelect' and consumes them using a monadic--- left-fold. Uses default settings for 'Cursor' (batch size is 256 rows).-dbFoldM :: (MonadIO m, Model model)-        => Connection -> (b -> model -> m b) -> b -> DBSelect model -> m b-dbFoldM c act initial dbs = do-  cur <- liftIO $ curSelect c dbs-  go cur initial-  where go cur accm = do-          mres <- liftIO $ curNext cur-          case mres of-            Nothing -> return accm-            Just res -> act accm res >>= go cur---- | Streams results of a 'DBSelect' and consumes them using a monadic--- left-fold. Uses default settings for 'Cursor' (batch size is 256 rows).-dbFoldM_ :: (MonadIO m, Model model)-         => Connection -> (model -> m ()) -> DBSelect model -> m ()-dbFoldM_ c act dbs = dbFoldM c (const act) () dbs---- | Group the returned tuples by unique a's. Expects the query to return a's--- in sequence -- all rows with the same value for a must be grouped together,--- for example, by sorting the result on a's primary key column.-dbCollect :: (Model a, Model b)-           => Connection -> DBSelect (a :. b) -> IO [(a, [b])]-dbCollect c ab = dbFold c group [] ab-  where-    group :: (Model a, Model b) => [(a, [b])] -> (a :. b) -> [(a, [b])]-    group    []     (a :. b) = [(a, [b])]-    group ls@(l:_)  (a :. b) | primaryKey a /= primaryKey (fst l) = (a, [b]):ls-    group    (l:ls) (_ :. b) = (fst l, b:(snd l)):ls---- | Create a join of the 'selFields', 'selFrom', and 'selWhere'--- clauses of two 'DBSelect' queries.  Other fields are simply taken--- from the second 'DBSelect', meaning fields such as 'selWith',--- 'selGroupBy', and 'selOrderBy' in the in the first 'DBSelect' are--- entirely ignored.-dbJoin :: forall a b.-          (Model a, Model b) =>-          DBSelect a      -- ^ First table-          -> Query        -- ^ Join keyword (@\"JOIN\"@, @\"LEFT JOIN\"@, etc.)-          -> DBSelect b   -- ^ Second table-          -> Query  -- ^ Predicate (if any) including @ON@ or @USING@ keyword-          -> DBSelect (a :. b)-dbJoin left joinOp right onClause = addWhere_ (selWhere left) right {-    selFields = Query $ S.concat [fromQuery $ selFields left, ", ",-                                  fromQuery $ selFields right]-  , selFrom = newfrom-  }-  where idab = modelIdentifiers :: ModelIdentifiers (a :. b)-        newfrom | nullFrom $ selFrom right = selFrom left-                | nullFrom $ selFrom left = selFrom right-                | otherwise = FromJoin (selFrom left) joinOp (selFrom right)-                              onClause (modelQTable idab)---- | A version of 'dbJoin' that uses 'modelDBSelect' for the joined--- tables.-dbJoinModels :: (Model a, Model b) =>-                Query           -- ^ Join keyword-                -> Query        -- ^ @ON@ or @USING@ predicate-                -> DBSelect (a :. b)-dbJoinModels kw on = dbJoin modelDBSelect kw modelDBSelect on---- | Restrict the fields returned by a DBSelect to be those of a--- single 'Model' @a@.  It only makes sense to do this if @a@ is part--- of @something_containing_a@, but no static check is performed that--- this is the case.  If you @dbProject@ a type that doesn't make--- sense, you will get a runtime error from a failed database query.-dbProject :: forall a something_containing_a.-             (Model a) => DBSelect something_containing_a -> DBSelect a-{-# INLINE dbProject #-}-dbProject dbs = r-  where sela = modelDBSelect :: DBSelect a-        r = dbs { selFields = selFields sela }---- | Like 'dbProject', but renders the entire input 'DBSelect' as a--- subquery.  Hence, you can no longer mention fields of models other--- than @a@ that might be involved in joins.  The two advantages of--- this approach are 1) that you can once again join to tables that--- were part of the original query without worrying about row aliases,--- and 2) that all terms of the 'DBSelect' will be faithrully rendered--- into the subquery (whereas otherwise they could get dropped by join--- operations).  Generally you will still want to use 'dbProject', but--- @dbProject'@ is available when needed.-dbProject' :: forall a something_containing_a.-              (Model a) => DBSelect something_containing_a -> DBSelect a-dbProject' dbs = r-  where sela = modelDBSelect :: DBSelect a-        ida = modelIdentifiers :: ModelIdentifiers a-        Just mq = modelQualifier ida-        q = toQuery $ fromChar '(' <>-            buildDBSelect dbs { selFields = selFields sela } <>-            fromByteString ") AS " <> fromByteString mq-        r = sela { selFrom = FromModel q $ modelQTable ida }--mergeFromClauses :: S.ByteString -> FromClause -> FromClause -> FromClause-mergeFromClauses canon left right =-  case go left of-    (fc, 1) -> fc-    (_, 0)  -> error $ "mergeFromClauses could not find " ++ show canon-    (_, _)  -> error $ "mergeFromClauses found duplicate " ++ show canon-  where go fc | fcCanonical fc == canon = (right, 1 :: Int)-        go (FromJoin l op r on ffc) =-          case (go l, go r) of-            ((lfc, ln), (rfc, rn)) -> (FromJoin lfc op rfc on ffc, ln + rn)-        go fc = (fc, 0)---- | Nest two type-compatible @JOIN@ queries.  As with 'dbJoin',--- fields of the first @JOIN@ (the @'DBSelect' (a :. b)@) other than--- 'selFields', 'selFrom', and 'selWhere' are entirely ignored.-dbNest :: forall a b c. (Model a, Model b) =>-          DBSelect (a :. b) -> DBSelect (b :. c) -> DBSelect (a :. b :. c)-dbNest left right = addWhere_ (selWhere left) right {-    selFields = fields-  , selFrom = mergeFromClauses nameb (selFrom left) (selFrom right)-  }-  where nameb = modelQTable (modelIdentifiers :: ModelIdentifiers b)-        acols = modelQColumns (modelIdentifiers :: ModelIdentifiers a)-        colcomma c r = fromByteString c <> fromByteString ", " <> r-        fields = toQuery $ foldr colcomma (qBuilder $ selFields right)-                 acols---- | Like 'dbNest', but projects away the middle type @b@.-dbChain :: (Model a, Model b, Model c) =>-           DBSelect (a :. b) -> DBSelect (b :. c) -> DBSelect (a :. c)-dbChain left right = dbProject $ dbNest left right
− Database/PostgreSQL/ORM/Model.hs 
@@ -1,1168 +0,0 @@-{-# LANGUAGE DeriveDataTypeable #-}-{-# LANGUAGE DeriveGeneric #-}-{-# LANGUAGE DefaultSignatures #-}-{-# LANGUAGE FlexibleContexts #-}-{-# LANGUAGE FlexibleInstances #-}-{-# LANGUAGE ScopedTypeVariables #-}-{-# LANGUAGE TypeOperators #-}-{-# LANGUAGE OverloadedStrings #-}-{-# LANGUAGE GeneralizedNewtypeDeriving #-}-{-# LANGUAGE CPP #-}---- | The main database ORM interface. This module contains--- functionality for moving a Haskell data structure in and out of a--- database table.------ The most important feature is the 'Model' class, which encodes a--- typed database interface (i.e., the ORM layer). This class has a--- default implementation for types that are members of the 'Generic'--- class (using GHC's @DeriveGeneric@ extension), provided the--- following conditions hold:------   1. The data type must have a single constructor that is defined---      using record selector syntax.------   2. The very first field of the data type must be a 'DBKey' to---      represent the primary key.  Other orders will cause a---      compilation error.------   3. Every field of the data structure must be an instance of---      'FromField' and 'ToField'.------ If these three conditions hold and your database naming scheme--- follows the conventions of 'defaultModelInfo'--namely that the--- table name is the same as the type name with the first character--- downcased, and the field names are the same as the column--- names--then it is reasonable to have a completely empty (default)--- instance declaration:------ >   data MyType = MyType { myKey :: !DBKey--- >                        , myName :: !S.ByteString--- >                        , myCamelCase :: !Int--- >                        , ...--- >                        } deriving (Show, Generic)--- >   instance Model MyType------ The default 'modelInfo' method is called 'defaultModelInfo'. You--- may wish to use almost all of the defaults, but tweak a few things.--- This is easily accomplished by overriding a few fields of the--- default structure. For example, suppose your database columns use--- exactly the same name as your Haskell field names, but the name of--- your database table is not the same as the name of the Haskell data--- type. You can override the database table name (field 'modelTable')--- as follows:------ >   instance Model MyType where--- >       modelInfo = defaultModelInfo { modelTable = "my_type" }------ Finally, if you dislike the conventions followed by--- 'defaultModelInfo', you can simply implement an alternate pattern.--- An example of this is 'underscoreModelInfo', which strips a prefix--- off every field name and converts everything from camel-case to--- underscore notation:------ >   instance Model MyType where--- >       modelInfo = underscoreModelInfo "my"------ The above code will associate @MyType@ with a database table--- @my_type@ having column names @key@, @name@, @camel_case@, etc.------ You can implement other patterns like 'underscoreModelInfo' by--- calling 'defaultModelInfo' and modifying the results.--- Alternatively, you can directly call the lower-level functions from--- which 'defaultModelInfo' is built ('defaultModelTable',--- 'defaultModelColumns', 'defaultModelGetPrimaryKey').-module Database.PostgreSQL.ORM.Model (-      -- * The Model class-      Model(..), ModelInfo(..), ModelIdentifiers(..), ModelQueries(..)-    , underscoreModelInfo-      -- * Data types for holding primary keys-    , DBKeyType, DBKey(..), isNullKey-    , DBRef, DBRefUnique, GDBRef(..), mkDBRef-      -- * Database operations on Models-    , findAll, findRow, save, save_, trySave, destroy, destroyByRef-      -- * Functions for accessing and using Models-    , modelName, primaryKey, modelSelectFragment-    , LookupRow(..), UpdateRow(..), InsertRow(..)-      -- * Table aliases-    , As(..), fromAs, toAs, RowAlias(..)-      -- * Low-level functions providing manual access to defaults-    , defaultModelInfo-    , defaultModelTable, defaultModelColumns, defaultModelGetPrimaryKey-    , defaultModelIdentifiers-    , defaultModelWrite-    , defaultModelQueries-    , defaultModelLookupQuery, defaultModelUpdateQuery-    , defaultModelInsertQuery, defaultModelDeleteQuery-      -- * Helper functions and miscellaneous internals-    , quoteIdent, NormalRef(..), UniqueRef(..)-    , ModelCreateInfo(..), emptyModelCreateInfo-    , defaultFromRow, defaultToRow-    , printq-      -- ** Helper classes-      -- $HelperClasses-    , GPrimaryKey0, GColumns, GDatatypeName-    , GFromRow, GToRow-    ) where--import Control.Applicative-import Control.Exception-import Control.Monad-import qualified Data.Aeson as A-import qualified Data.ByteString as S-import qualified Data.ByteString.Char8 as S8-import qualified Data.Text as T-import qualified Data.Text.Encoding as T-import Data.Char-import Data.Data-import Data.Int-import qualified Data.HashMap.Strict as H-import Data.Maybe-import Data.Monoid-import Data.List hiding (find)-import Data.String-import Database.PostgreSQL.Simple-import Database.PostgreSQL.Simple.FromField-import Database.PostgreSQL.Simple.FromRow-import Database.PostgreSQL.Simple.ToField-import Database.PostgreSQL.Simple.ToRow-import Database.PostgreSQL.Simple.Types-import Database.PostgreSQL.ORM.Validations-import GHC.Generics--import Data.RequireSelector-import Database.PostgreSQL.Escape (quoteIdent)---- | A type large enough to hold database primary keys.  Do not use--- this type directly in your data structures.  Use 'DBKey' to hold a--- `Model`'s primary key and 'DBRef' to reference the primary key of--- another model.-type DBKeyType = Int64---- | The type of the Haskell data structure field containing a model's--- primary key.------ Every 'Model' must have exactly one @DBKey@, and the @DBKey@ must--- be the `Model`'s very first field in the Haskel data type--- definition.  (The ordering is enforced by--- 'defaultModelGetPrimaryKey', which, through use of the--- @DeriveGeneric@ extension, fails to compile when the first field is--- not a @DBKey@.)------ Each 'Model' stored in the database should have a unique non-null--- primary key.  However, the key is determined at the time the--- 'Model' is inserted into the database.  While you are constructing--- a new 'Model' to insert, you will not have its key.  Hence, you--- should use the value @NullKey@ to let the database chose the key.------ If you wish to store a `Model`'s primary key as a reference in--- another 'Model', do not copy the 'DBKey' structure.  Use 'mkDBRef'--- to convert the `Model`'s primary key to a foreign key reference.-data DBKey = DBKey !DBKeyType | NullKey deriving (Data, Typeable, Generic)--instance A.ToJSON DBKey where-  toJSON NullKey = A.Null-  toJSON (DBKey k) = A.toJSON k--instance A.FromJSON DBKey where-  parseJSON (A.Number a) = return $ DBKey (floor a)-  parseJSON A.Null = return NullKey-  parseJSON _ = error "Expected Number or Null"--instance Eq DBKey where-  (DBKey a) == (DBKey b) = a == b-  _         == _         = error "compare NullKey"-instance Ord DBKey where-  compare (DBKey a) (DBKey b) = compare a b-  compare _ _                 = error "compare NullKey"--instance Show DBKey where-  showsPrec n (DBKey k) = showsPrec n k-  showsPrec _ NullKey   = ("NullKey" ++)--instance FromField DBKey where-  fromField _ Nothing = pure NullKey-  fromField f bs      = DBKey <$> fromField f bs-instance ToField DBKey where-  toField (DBKey k) = toField k-  toField NullKey   = toField Null---- | Returns 'True' when a 'DBKey' is 'NullKey'.-isNullKey :: DBKey -> Bool-isNullKey NullKey = True-isNullKey _       = False----- | Many operations can take either a 'DBRef' or a 'DBRefUnique'--- (both of which consist internally of a 'DBKeyType').  Hence, these--- two types are just type aliases to a generalized reference type--- @GDBRef@, where @GDBRef@'s first type argument, @reftype@, is a--- phantom type denoting the flavor of reference ('NormalRef' or--- 'UniqueRef').-newtype GDBRef reftype table = DBRef DBKeyType-  deriving (Eq, Data, Typeable, Num, Integral, Real, Ord, Enum, Bounded, Generic)--instance A.ToJSON (GDBRef t a) where-  toJSON (DBRef k) = A.toJSON k--instance A.FromJSON (GDBRef t a) where-  parseJSON (A.Number n) = return $ DBRef (floor n)-  parseJSON _ = error "Expected Number"--instance (Model t) => Show (GDBRef rt t) where-  showsPrec n (DBRef k) = showsPrec n k-instance (Model t) => Read (GDBRef rt t) where-  readsPrec n str = map wrap $ readsPrec n str-    where wrap (k, s) = (DBRef k, s)-instance FromField (GDBRef rt t) where-  {-# INLINE fromField #-}-  fromField f bs = DBRef <$> fromField f bs-instance ToField (GDBRef rt t) where-  {-# INLINE toField #-}-  toField (DBRef k) = toField k---- | Phantom type for instantiating 'GDBRef' that represents a one-to-many--- relationship between tables.-data NormalRef = NormalRef deriving (Show, Data, Typeable)---- | A @DBRef T@ represents a many-to-one relationship between tables. For--- example, if type @A@ contains a @DBRef B@, then each @B@ is associated--- with many @A@'s. By contrast, a @'DBRefUnique'@ represents a one-to-one--- relationship.------ @DBRef@ is a type alias of kind @* -> *@.  The type @DBRef T@--- references an instance of type @T@ by the primary key of its--- database row. The type argument @T@ should be an instance of--- 'Model'.-type DBRef = GDBRef NormalRef---- | Phantom type for instantiating 'GDBRef' that represents a one-to-one--- relationship between tables.-data UniqueRef = UniqueRef deriving (Show, Data, Typeable)---- | A @DBRefUnique T@ represents a one-to-one relationship between types. For--- example, if type @A@ contains a @DBRefUnique B@, then each @A@ is associated--- with one (or at most one) @B@, and each @B@ has one (or at most one) @A@--- associated with it.------ By contrast, a @'DBRef'@ represents a many-to-one relationship.-type DBRefUnique = GDBRef UniqueRef--- Functionally, @DBRefUnique@ and @DBRef@ are treated the same by--- this module.  However, other modules make a distinction.  In--- particular, the 'modelCreateStatement' corresponding to a--- 'DBRefUnique' will include a @UNIQUE@ constraint.---- | Create a reference to the primary key of a 'Model', suitable for--- storing in a 'DBRef' or 'DBRefUnique' field of a different 'Model'.-mkDBRef :: (Model a) => a -> GDBRef rt a-mkDBRef a-  | (DBKey k) <- primaryKey a = DBRef k-  | otherwise = error $ "mkDBRef " ++ S8.unpack (modelName a) ++ ": NullKey"----- | A @ModelInfo T@ contains the information necessary for mapping--- @T@ to a database table.  Each @'Model'@ type has a single--- @ModelInfo@ associated with it, accessible through the 'modelInfo'--- method of the 'Model' class.  Note the table and column names must--- all be unquoted in this data structure, as they will later be--- quoted using 'quoteIdent' by the 'modelIdentifiers' method.-data ModelInfo a = ModelInfo {-    modelTable :: !S.ByteString-    -- ^ The name of the database table corresponding to this model.-    -- The default 'modelInfo' instance uses 'defaultModelTable',-    -- which is the name of your data type with the first letter-    -- downcased.-  , modelColumns :: ![S.ByteString]-    -- ^ The names of the database columns corresponding to fields of-    -- this model.  The column names should appear in the order in-    -- which the fields are defined in the Haskell data type @a@-    -- (which should also be the order in which 'modelRead' parses-    -- them to an @a@ and 'modelWrite' marshalls them).-    ---    -- Note that all queries generated by the library specify explicit-    -- column names.  Hence the order of columns does not need to-    -- match their order in the database table.  They should instead-    -- match the order of fields in the Haskell data structure.-    ---    -- The default, given by 'defaultModelColumns', is to use the-    -- Haskell field names for @a@.  This default will fail to compile-    -- if @a@ is not defined using record syntax.-  , modelPrimaryColumn :: !Int-    -- ^ The 0-based index of the primary key column in-    -- 'modelColumns'.  This should be 0 when your data structure's-    -- first field is its 'DBKey' (highly recommended, and required by-    -- 'defaultModelGetPrimaryKey').  If you customize this field, you-    -- must also customize 'modelGetPrimaryKey'--no check is made that-    -- the two are consistent.-  , modelGetPrimaryKey :: !(a -> DBKey)-    -- ^ Return the primary key of a particular model instance.  If-    -- you customize this field, you must also customize-    -- 'modelPrimaryColumn'--no check is made that the two are-    -- consistent.-  }--instance Show (ModelInfo a) where-  show a = intercalate " " [-      "Model", show $ modelTable a, show $ modelColumns a-    , show $ modelPrimaryColumn a , "?"]----- $HelperClasses------ These classes are used internally to manipulate the 'Rep'--- representations of 'Generic' data structures.  You should not be--- defining instances of or using these classes directly.  The names--- are exported so that you can include them in the context of the--- type signatures of your functions, should you wish to make use of--- the various @default@... funcitons in this file.---- | This class returns the name of a datatype.-class GDatatypeName f where-  gDatatypeName :: f p -> String-instance (Datatype c) => GDatatypeName (D1 c f) where -  gDatatypeName a = datatypeName a--- | The default name of the database table corresponding to a Haskell--- type.  The default is the same as the type name with the first--- letter converted to lower-case.  (The rationale is that Haskell--- requires types to start with a capital letter, but all-lower-case--- table names are easier to use in queries because PostgreSQL--- generally does not require them to be quoted.)-defaultModelTable :: (Generic a, GDatatypeName (Rep a)) => a -> S.ByteString-defaultModelTable = fromString . caseFold. gDatatypeName . from-  where caseFold (h:t) = toLower h:t-        caseFold s     = s---- | This class extracts the field names of a Haskell data structure. Only--- defined for types with a single constructor that uses record syntax.-class GColumns f where-  gColumns :: f p -> [S.ByteString]-instance GColumns U1 where-  gColumns _ = []-instance (Selector c) => GColumns (M1 S c f) where-  gColumns s = [fromString $ selName s]-instance (GColumns a, GColumns b) => GColumns (a :*: b) where-  gColumns ~(a :*: b) = gColumns a ++ gColumns b-instance (GColumns f) => GColumns (M1 C c f) where-  gColumns ~(M1 fp) = gColumns fp-instance (GColumns f) => GColumns (M1 D c f) where-  gColumns ~(M1 fp) = gColumns fp--- | Returns the Haskell field names in a data structure.-defaultModelColumns :: (Generic a, GColumns (Rep a)) => a -> [S.ByteString]-defaultModelColumns = gColumns . from---- | This class extracts the first field in a data structure when the--- field is of type 'DBKey'.  If you get a compilation error because--- of this class, then move the 'DBKey' first in your data structure.-class GPrimaryKey0 f where-  gPrimaryKey0 :: f p -> DBKey-instance GPrimaryKey0 (S1 c (K1 i DBKey)) where-  {-# INLINE gPrimaryKey0 #-}-  gPrimaryKey0 (M1 (K1 k)) = k-instance (GPrimaryKey0 a) => GPrimaryKey0 (a :*: b) where-  {-# INLINE gPrimaryKey0 #-}-  gPrimaryKey0 (a :*: _) = gPrimaryKey0 a-instance (GPrimaryKey0 f) => GPrimaryKey0 (C1 c f) where-  {-# INLINE gPrimaryKey0 #-}-  gPrimaryKey0 (M1 fp) = gPrimaryKey0 fp-instance (GPrimaryKey0 f) => GPrimaryKey0 (D1 c f) where-  {-# INLINE gPrimaryKey0 #-}-  gPrimaryKey0 (M1 fp) = gPrimaryKey0 fp---- | Extract the primary key of type 'DBKey' from a model when the--- 'DBKey' is the first element of the data structure.  Fails to--- compile if the first field is not of type 'DBKey'.-defaultModelGetPrimaryKey :: (Generic a, GPrimaryKey0 (Rep a)) => a -> DBKey-{-# INLINE defaultModelGetPrimaryKey #-}-defaultModelGetPrimaryKey = gPrimaryKey0 . from---class GFromRow f where-  gFromRow :: RowParser (f p)-instance GFromRow U1 where-  {-# INLINE gFromRow #-}-  gFromRow = return U1-instance (FromField c) => GFromRow (K1 i c) where-  {-# INLINE gFromRow #-}-  gFromRow = K1 <$> field-instance (GFromRow a, GFromRow b) => GFromRow (a :*: b) where-  {-# INLINE gFromRow #-}-  gFromRow = (:*:) <$> gFromRow <*> gFromRow-instance (GFromRow f) => GFromRow (M1 i c f) where-  {-# INLINE gFromRow #-}-  gFromRow = M1 <$> gFromRow--- | This function provides a 'fromRow' function for 'Generic' types,--- suitable as a default of the 'FromRow' class.  This module uses it--- as the default implementation of 'modelRead'.-defaultFromRow :: (Generic a, GFromRow (Rep a)) => RowParser a-{-# INLINE defaultFromRow #-}-defaultFromRow = to <$> gFromRow---class GToRow f where-  gToRow :: f p -> [Action]-instance GToRow U1 where-  gToRow _ = []-instance (ToField c) => GToRow (K1 i c) where-  gToRow (K1 c) = [toField c]-instance (GToRow a, GToRow b) => GToRow (a :*: b) where-  gToRow (a :*: b) = gToRow a ++ gToRow b-instance (GToRow f) => GToRow (M1 i c f) where-  gToRow (M1 fp) = gToRow fp--- | This function provides a 'toRow' function for 'Generic' types--- that marshalls each field of the data type in the order in which it--- appears in the type definition.  This function is /not/ a suitable--- implementation of 'modelWrite' (since it marshals the primary key,--- which is not supposed to be written).  However, it is required--- internally by 'defaultModelWrite', and exposed in the unlikely--- event it is of use to alternate generic 'modelWrite' functions.--- You probably don't want to call this function.-defaultToRow :: (Generic a, GToRow (Rep a)) => a -> [Action]-defaultToRow = gToRow . from---- | Removes a single element from the list at the position specified.--- (Internal)-deleteAt :: Int -> [a] -> [a]-deleteAt 0 (_:t) = t-deleteAt n (h:t) = h:deleteAt (n-1) t-deleteAt _ _     = []---- | Returns a series of 'Action's serializing each field of a data--- structure (in the order of the Haskell datatype definition),--- /except/ the primary key, since the primary key should never be--- written to a database.  Every field must be an instance of--- 'ToField'.-defaultModelWrite :: forall a. (Model a, Generic a, GToRow (Rep a))-                  => a -> [Action]-{-# INLINE defaultModelWrite #-}-defaultModelWrite a = deleteAt pki $ defaultToRow a-  where pki = modelPrimaryColumn (modelInfo :: ModelInfo a)---- | The default definition of 'modelInfo'. See the documentation at--- 'Model' for more information.  Sets 'modelTable' to the name of the--- type with the first character converted to lower-case.  Sets--- 'modelColumns' to the names of the Haskell field selectors.  Sets--- 'modelPrimaryColumn' to @0@ and extracts the first field of the--- structure for 'modelGetPrimaryKey'.  Will fail to compile unless--- the data structure is defined with record syntax and that its first--- field is of type 'DBKey'.------ Note that defaults for the individual fields are available in--- separate functions (e.g., 'defaultModelTable') with fewer class--- requirements in the context, in case you want to make piecemeal use--- of defaults.  The default for 'modelPrimaryColumn' is 0.  If you--- overwrite that, you will need to overwrite 'modelGetPrimaryKey' as--- well (and likely vice versa).-defaultModelInfo :: forall a.-                    (Generic a, GDatatypeName (Rep a), GColumns (Rep a)-                    , GPrimaryKey0 (Rep a)) => ModelInfo a-defaultModelInfo = m-  where m = ModelInfo { modelTable = defaultModelTable a-                      , modelColumns = defaultModelColumns a-                      , modelPrimaryColumn = 0-                      , modelGetPrimaryKey = defaultModelGetPrimaryKey-                      }-        a = undefined :: a---- | An alternate 'Model' pattern in which Haskell type and field--- names are converted from camel-case to underscore notation.  The--- first argument is a prefix to be removed from field names (since--- Haskell requires field names to be unique across data types, while--- SQL allows the same column names to be used in different tables).------ For example:------ > data Bar = Bar {--- >     barId :: !DBKey--- >   , barNameOfBar :: !String--- >   , barParent :: !(Maybe (DBRef Bar))--- >   } deriving (Show, Generic)--- >--- > instance Model Bar where modelInfo = underscoreModelInfo "bar"------ would associate type @Bar@ with a database table called @bar@ with--- fields @id@, @name_of_bar@, and @parent@.-underscoreModelInfo :: (Generic a, GToRow (Rep a), GFromRow (Rep a)-                       , GPrimaryKey0 (Rep a), GColumns (Rep a)-                       , GDatatypeName (Rep a)) =>-                       S.ByteString -> ModelInfo a-underscoreModelInfo prefix = def {-      modelTable = toUnderscore True $ modelTable def-    , modelColumns = map fixCol $ modelColumns def-    }-  where def = defaultModelInfo-        plen = S.length prefix-        fixCol c = toUnderscore False $ stripped-          where stripped | prefix `S.isPrefixOf` c = S.drop plen c-                         | otherwise               = c---- | Convert a name from camel-case to underscore notation.--- I.e., names of the form "MSizeForm" are changed to "MSize_From".--- @skipFirst@ determines if the first character should be ignored--- in the conversion.-toUnderscore :: Bool -> S.ByteString -> S.ByteString-toUnderscore skipFirst | skipFirst = S8.pack . skip . S8.unpack-                       | otherwise = S8.pack . go True . S8.unpack-  where skip "" = ""-        skip (h:t) = toLower h : go True t-        go _ ""                      = ""-        go _ (h:t) | not (isUpper h) = h : go False t-        go True (h:t)                = toLower h : go True t-        go False (h:t)               = '_' : toLower h : go True t----- | SQL table and column identifiers that should be copied verbatim--- into queries.  For normal models, these will simply be quoted--- versions of the fields in the corresponding 'ModelInfo'.  However,--- for special cases, the fields of this structure can contain--- unquoted SQL including @JOIN@ keywords.  In the case of joins,--- different elements of 'modelQColumns' may be qualified by different--- table names.------ Note that 'modelQColumns' and 'modelQPrimaryColumn' both contain--- table-qualified names (e.g., @\"\\\"my_type\\\".\\\"key\\\"\"@),--- while 'modelQWriteColumns' contains only the quoted column names.-data ModelIdentifiers a = ModelIdentifiers {-    modelQTable :: !S.ByteString-    -- ^ Literal SQL for the name of the table.-  , modelQColumns :: ![S.ByteString]-    -- ^ Literal SQL for each, table-qualified column.-  , modelQPrimaryColumn :: S.ByteString-    -- ^ Literal SQL for the model's table-qualified primary key-    -- column.-  , modelQWriteColumns :: [S.ByteString]-    -- ^ Literal SQL for all the columns except the primary key.-    -- These are the columns that should be included in an @INSERT@ or-    -- @UPDATE@.  Note that unlike the other fields, these column-    -- names should /not/ be table-qualified.-  , modelQualifier :: !(Maybe S.ByteString)-    -- ^ When all columns in 'modelQColumns' are qualified by the same-    -- table name, this field contains 'Just' the table name.-    -- For the ':.' type (in which different columns have different-    -- table qualifications), this field is 'Nothing'.-    ---    -- For normal models, this field will be identical to-    -- 'modelQTable'.  However, for 'As' models, 'modelQTable' will-    -- contain unquoted SQL such as @\"\\\"MyType\\\" AS-    -- \\\"my_alias\\\"\"@, in which case @modelQualifier@ will-    -- contain @'Just' \"\\\"my_alias\\\"\"@.-  , modelOrigTable :: !(Maybe S.ByteString)-    -- ^ The original, unquoted name of the table representing the-    -- model in the database.  Ordinarily, this should be the same as-    -- 'modelTable' in 'ModelInfo', but in the case of 'As' aliases,-    -- the 'modelTable' is an alias, and 'modelOrigTable' is the-    -- original table.  'Nothing' for joins.-  } deriving (Show)---- | The default simply quotes the 'modelInfo' and 'modelColumns'--- fields of 'ModelInfo' using 'quoteIdent'.-defaultModelIdentifiers :: ModelInfo a -> ModelIdentifiers a-defaultModelIdentifiers mi = ModelIdentifiers {-    modelQTable = qtable-  , modelQColumns = qcols-  , modelQPrimaryColumn = qcols !! pki-  , modelQWriteColumns = deleteAt pki $ map quoteIdent $ modelColumns mi-  , modelQualifier = Just qtable-  , modelOrigTable = Just $ modelTable mi-  }-  where qtable = quoteIdent (modelTable mi)-        qcol c = S.concat [qtable, ".", quoteIdent c]-        qcols = map qcol $ modelColumns mi-        pki = modelPrimaryColumn mi---- | Standard CRUD (create\/read\/update\/delete) queries on a model.-data ModelQueries a = ModelQueries {-    modelLookupQuery :: !Query-    -- ^ A query template for looking up a model by its primary key.-    -- Expects a single query parameter, namely the 'DBKey' or 'DBRef'-    -- being looked up.-  , modelUpdateQuery :: !Query-    -- ^ A query template for updating an existing 'Model' in the-    -- database.  Expects as query parameters a value for every column-    -- of the model /except/ the primary key, followed by the primary-    -- key.  (The primary key is not written to the database, just-    -- used to select the row to change.)-  , modelInsertQuery :: !Query-    -- ^ A query template for inserting a new 'Model' in the database.-    -- The query parameters are values for all columns /except/ the-    -- primary key.  The query returns the full row as stored in the-    -- database (including the values of fields, such as the primary-    -- key, that have been chosen by the database server).-  , modelDeleteQuery :: !Query-    -- ^ A query template for deleting a 'Model' from the database.-    -- Should have a single query parameter, namely the 'DBKey' of the-    -- row to delete.-  } deriving (Show)---- | Default SQL lookup query for a model.-defaultModelLookupQuery :: ModelIdentifiers a -> Query-defaultModelLookupQuery mi = Query $ S.concat [-  modelSelectFragment mi, " WHERE ", modelQPrimaryColumn mi, " = ?"-  ]---- | Default SQL update query for a model.-defaultModelUpdateQuery :: ModelIdentifiers a -> Query-defaultModelUpdateQuery mi = Query $ S.concat [-    "UPDATE ", modelQTable mi, " SET "-    , S.intercalate ", " $ map (<> " = ?") $ modelQWriteColumns mi-    , " WHERE ", modelQPrimaryColumn mi, " = ?"-    , " RETURNING ", S.intercalate ", " (modelQColumns mi)-  ]---- | Default SQL insert query for a model.-defaultModelInsertQuery :: ModelIdentifiers a -> Query-defaultModelInsertQuery mi-  | null (modelQWriteColumns mi) = Query $ S.concat [-    "INSERT INTO ", modelQTable mi, " DEFAULT VALUES RETURNING "-    , S.intercalate ", " $ modelQColumns mi ]-  | otherwise = Query $ S.concat $ [-  "INSERT INTO ", modelQTable mi-  , " (", S.intercalate ", " $ modelQWriteColumns mi-  , ") VALUES (", S.intercalate ", " $ map (const "?") $ modelQWriteColumns mi-  , ") RETURNING ", S.intercalate ", " $ modelQColumns mi-  ]---- | Default SQL delete query for a model.-defaultModelDeleteQuery :: ModelIdentifiers a -> Query-defaultModelDeleteQuery mi = Query $ S.concat [-  "DELETE FROM ", modelQTable mi-  , " WHERE ", modelQPrimaryColumn mi, " = ?"-  ]---- | The default value of 'modelQueries'.-defaultModelQueries :: ModelIdentifiers a -> ModelQueries a-defaultModelQueries mi = ModelQueries {-    modelLookupQuery = defaultModelLookupQuery mi-  , modelUpdateQuery = defaultModelUpdateQuery mi-  , modelInsertQuery = defaultModelInsertQuery mi-  , modelDeleteQuery = defaultModelDeleteQuery mi-  }---- | Extra information for "Database.PostgreSQL.ORM.CreateTable".  You--- probably don't need to use this.-data ModelCreateInfo a = ModelCreateInfo {-    modelCreateColumnTypeExceptions :: ![(S.ByteString, S.ByteString)]-    -- ^ A list of (column-name, type) pairs for which you want to-    -- override the default.-  , modelCreateExtraConstraints :: !S.ByteString-    -- ^ Extra constraints to stick at the end of the @CREATE TABLE@-    -- statement.-  } deriving (Show)---- | A 'ModelCreateInfo' that doesn't imply any extra constraints or--- exceptions.-emptyModelCreateInfo :: ModelCreateInfo a-emptyModelCreateInfo = ModelCreateInfo {-    modelCreateColumnTypeExceptions = []-  , modelCreateExtraConstraints = S.empty-  }---- | The class of data types that represent a database table.  This--- class conveys information necessary to move a Haskell data--- structure in and out of a database table.  The most important field--- is 'modelInfo', which describes the database table and column--- names.  'modelInfo' has a reasonable default implementation for--- types that are members of the 'Generic' class (using GHC's--- @DeriveGeneric@ extension), provided the following conditions hold:------   1. The data type must have a single constructor that is defined---      using record selector syntax.------   2. The very first field of the data type must be a 'DBKey' to---      represent the primary key.  Other orders will cause a---      compilation error.------   3. Every field of the data structure must be an instance of---      'FromField' and 'ToField'.------ If these three conditions hold and your database naming scheme--- follows the conventions of 'defaultModelInfo'--namely that the--- table name is the same as the type name with the first character--- downcased, and the field names are the same as the column--- names--then it is reasonable to have a completely empty (default)--- instance declaration:------ >   data MyType = MyType { myKey :: !DBKey--- >                        , myName :: !S.ByteString--- >                        , myCamelCase :: !Int--- >                        , ...--- >                        } deriving (Show, Generic)--- >   instance Model MyType------ The default 'modelInfo' method is called 'defaultModelInfo'.  You--- may wish to use almost all of the defaults, but tweak a few things.--- This is easily accomplished by overriding a few fields of the--- default structure.  For example, suppose your database columns use--- exactly the same name as your Haskell field names, but the name of--- your database table is not the same as the name of the Haskell data--- type.  You can override the database table name (field--- 'modelTable') as follows:------ >   instance Model MyType where--- >       modelInfo = defaultModelInfo { modelTable = "my_type" }------ Finally, if you dislike the conventions followed by--- 'defaultModelInfo', you can simply implement an alternate pattern.--- An example of this is 'underscoreModelInfo', which strips a prefix--- off every field name and converts everything from camel-case to--- underscore notation:------ >   instance Model MyType where--- >       modelInfo = underscoreModelInfo "my"------ The above code will associate @MyType@ with a database table--- @my_type@ having column names @key@, @name@, @camel_case@, etc.------ You can implement other patterns like 'underscoreModelInfo' by--- calling 'defaultModelInfo' and modifying the results.--- Alternatively, you can directly call the lower-level functions from--- which 'defaultModelInfo' is built ('defaultModelTable',--- 'defaultModelColumns', 'defaultModelGetPrimaryKey').-class Model a where-  -- | @modelInfo@ provides information about how the Haskell data-  -- type is stored in the database, in the form of a 'ModelInfo' data-  -- structure.  Among other things, this structure specifies the name-  -- of the database table, the names of the database columns-  -- corresponding to the Haskell data structure fields, and the-  -- position of the primary key in both the database columns and the-  -- Haskell data structure.-  modelInfo :: ModelInfo a-  default modelInfo :: (Generic a, GDatatypeName (Rep a), GColumns (Rep a)-                       , GPrimaryKey0 (Rep a)) => ModelInfo a-  {-# INLINE modelInfo #-}-  modelInfo = defaultModelInfo--  -- | 'modelIdentifiers' contains the table and column names verbatim-  -- as they should be inserted into SQL queries.  For normal models,-  -- these are simply double-quoted (with 'quoteIdent') versions of-  -- the names in 'modelInfo', with the column names qualified by the-  -- double-quoted table name.  However, for special cases such as-  -- join relations (with ':.')  or row aliases (with 'As'),-  -- 'modelIdentifiers' can modify the table name with unquoted SQL-  -- identifiers (such as @JOIN@ and @AS@) and change the qualified-  -- column names appropriately.-  modelIdentifiers :: ModelIdentifiers a-  {-# INLINE modelIdentifiers #-}-  modelIdentifiers = defaultModelIdentifiers modelInfo--  -- | @modelRead@ converts from a database 'query' result to the-  -- Haskell data type of the @Model@, namely @a@.  Note that if type-  -- @a@ is an instance of 'FromRow', a fine definition of @modelRead@-  -- is @modelRead = fromRow@.  The default is to construct a row-  -- parser using the 'Generic' class.  However, it is crucial that-  -- the columns be parsed in the same order they are listed in the-  -- 'modelColumns' field of @a@'s 'ModelInfo' structure, and this-  -- should generally be the same order they are defined in the-  -- Haskell data structure.  Hence @modelRead@ should generally look-  -- like:-  ---  -- @-  --   -- Call 'field' as many times as there are fields in your type-  --   modelRead = Constructor \<$> 'field' \<*> 'field' \<*> 'field'-  -- @-  modelRead :: RowParser a-  default modelRead :: (Generic a, GFromRow (Rep a)) => RowParser a-  {-# INLINE modelRead #-}-  modelRead = defaultFromRow--  -- | Marshal all fields of @a@ /except/ the primary key.  As with-  -- 'modelRead', the fields must be marshalled in the same order the-  -- corresponding columns are listed in 'modelColumns', only with the-  -- primary key (generally column 0) deleted.-  ---  -- Do /not/ define this as 'toRow', even if @a@ is an instance of-  -- 'ToRow', because 'toRow' would include the primary key.-  -- Similarly, do /not/ define this as 'defaultToRow'.  On the other-  -- hand, it is reasonable for @modelWrite@ to return an error for-  -- degenerate models (such as joins) that should never be 'save'd.-  modelWrite :: a -> [Action]-  default modelWrite :: (Generic a, GToRow (Rep a)) => a -> [Action]-  {-# INLINE modelWrite #-}-  modelWrite = defaultModelWrite--  -- | @modelQueries@ provides pre-formatted 'Query' templates for-  -- 'findRow', 'save', and 'destroy'.  The default 'modelQueries'-  -- value is generated from 'modelIdentifiers' and should not be-  -- modified.  However, for degenerate tables (such as joins created-  -- with ':.'), it is reasonable to make 'modelQueries' always throw-  -- an exception, thereby disallowing ordinary queries and requiring-  -- use of more general query functions.-  ---  -- This method should either throw an exception or use the default-  -- implementation.-  modelQueries :: ModelQueries a-  {-# INLINE modelQueries #-}-  modelQueries = defaultModelQueries modelIdentifiers--  -- | Extra constraints, if any, to place in a @CREATE TABLE@-  -- statement.  Only used by "Database.PostgreSQL.ORM.CreateTable".-  modelCreateInfo :: ModelCreateInfo a-  modelCreateInfo = emptyModelCreateInfo--  -- | Perform a validation of the model, returning any errors if-  -- it is invalid.-  modelValid :: a -> ValidationError-  modelValid = const mempty---- | Degenerate instances of 'Model' for types in the 'ToRow' class--- are to enable extra 'ToRow' types to be included with ':.' in the--- result of 'dbSelect' queries.-degen_err :: a-degen_err = error "Attempt to use degenerate ToRow instance as Model"-#define DEGENERATE(ctx,t)             \-instance ctx => Model t where {       \-  modelInfo = degen_err;              \-  modelIdentifiers = degen_err;       \-  modelRead = fromRow;                \-  modelWrite _ = degen_err;           \-  modelCreateInfo = degen_err; }--DEGENERATE(FromField t, (Only t))-DEGENERATE(FromField t, [t])-DEGENERATE((FromField a, FromField b), (a, b))-DEGENERATE((FromField a, FromField b, FromField c), (a, b, c))-DEGENERATE((FromField a, FromField b, FromField c, FromField d), (a, b, c, d))-DEGENERATE((FromField a, FromField b, FromField c, FromField d, FromField e), \-           (a, b, c, d, e))--#undef DEGEN_ERR-#undef DEGENERATE---- | A degenerate model that lifts any model to a Maybe version. Returns--- 'Nothing' on a parse failure. Useful, for example, for performing outer--- joins:--- @--- dbJoin modelDBSelect "LEFT OUTER JOIN"---        (addWhere 'foo = 123' $ modelDBSelect)---        "USING a.id = b.a_id" :: (A :. Maybe B)--- @----instance forall a. Model a => Model (Maybe a) where-  modelInfo = mi_a { modelGetPrimaryKey = getPrimaryKey }-    where mi_a = modelInfo :: ModelInfo a-          getPrimaryKey Nothing  = NullKey-          getPrimaryKey (Just a) = modelGetPrimaryKey mi_a a--  modelIdentifiers = mi_a { modelQTable = modelQTable mi_a }-    where mi_a = modelIdentifiers :: ModelIdentifiers a--  modelQueries = mi_a { modelLookupQuery = modelLookupQuery mi_a }-    where mi_a = modelQueries :: ModelQueries a--  modelCreateInfo = error-    "Attempt to use degenerate Maybe (Model a) instance for ModelCreateInfo"--  modelValid = maybe mempty modelValid--  modelWrite = maybe [] modelWrite--  modelRead =-    Just `fmap` (modelRead :: RowParser a)-    <|> do-      let n = length $ modelColumns (modelInfo :: ModelInfo a)-      replicateM_ n (field :: RowParser AnyField)-      return Nothing---- | AnyField parses (simply by consuming) any SQL column.-data AnyField = AnyField--instance FromField AnyField where-  fromField _ _ = pure AnyField--joinModelIdentifiers :: forall a b. (Model a, Model b)-                     => ModelIdentifiers (a :. b)-joinModelIdentifiers = r-  where r = ModelIdentifiers {-              modelQTable = qtable-            , modelQColumns = modelQColumns mia ++ modelQColumns mib-            , modelQWriteColumns = error "attempt to write join relation"-            , modelQPrimaryColumn =-              error "attempt to use primary key of join relation"-            , modelQualifier = Nothing-            , modelOrigTable = Nothing-          }-        qtable | S.null $ modelQTable mib = modelQTable mia-               | S.null $ modelQTable mia = modelQTable mib-               | otherwise = S.concat [modelQTable mia, " CROSS JOIN "-                                      , modelQTable mib]-        mia = modelIdentifiers :: ModelIdentifiers a-        mib = modelIdentifiers :: ModelIdentifiers b---- | A degenerate instance of model representing a database join.  The--- ':.' instance does not allow normal model operations such as--- 'findRow', 'save', and 'destroy'.  Attempts to use such functions--- will result in an exception.-instance (Model a, Model b) => Model (a :. b) where-  modelInfo = error "attempt to access ModelInfo of join type :."-  modelIdentifiers = joinModelIdentifiers-  modelRead = (:.) <$> modelRead <*> modelRead-  modelWrite _ = error "attempt to write join type :. as a normal Model"-  modelQueries = error "attempt to perform standard query on join type :."---class GUnitType f where-  gUnitTypeName :: f p -> String-instance GUnitType (C1 c U1) where-  gUnitTypeName _ = error "gUnitTypeName"-instance GUnitType V1 where-  gUnitTypeName _ = error "gUnitTypeName"-instance (Datatype c, GUnitType f) => GUnitType (D1 c f) where-  gUnitTypeName = datatypeName---- | The class of types that can be used as tags in as 'As' alias.--- Such types should be unit types--in other words, have exactly one--- constructor where the constructor is nullary (take no arguments).--- The reason for this class is that the 'Model' instance for 'As'--- requires a way to extract the name of the row alias without having--- a concrete instance of the type.  This is provided by the--- 'rowAliasName' method (which must be non-strict).-class RowAlias a where-  rowAliasName :: g a row -> S.ByteString-  -- ^ Return the SQL identifier for the row alias.  This method must-  -- be non-strict in its argument.  Hence, it should discard the-  -- argument and return the name of the alias.  For example:-  ---  -- > {-# LANGUAGE OverloadedStrings #-}-  -- >-  -- > data My_alias = My_alias-  -- > instance RowAlias My_alias where rowAliasName _ = "my_alias"-  ---  -- Keep in mind that PostgreSQL folds unquoted identifiers to-  -- lower-case.  However, this library quotes row aliases in @SELECT@-  -- statements, thereby preserving case.  Hence, if you want to call-  -- construct a @WHERE@ clause without double-quoting row aliases in-  -- your 'Query', you should avoid capital letters in alias names.-  ---  -- A default implementation of @rowAliasName@ exists for unit types-  -- (as well as empty data declarations) in the 'Generic' class.  The-  -- default converts the first character of the type name to-  -- lower-case, following the logic of 'defaultModelTable'.-  default rowAliasName :: (Generic a, GUnitType (Rep a)) =>-                          g a row -> S.ByteString-  rowAliasName _ = fromString $ caseFold $ gUnitTypeName . from $ a-    where caseFold (h:t) = toLower h:t -- fold first character only-          caseFold []    = []-          a = undefined :: a---- | The newtype @As@ can be wrapped around an existing type to give--- it a table name alias in a query.  This is necessary when a model--- is being joined with itself, to distinguish the two joined--- instances of the same table.------ For example:------ @{-\# LANGUAGE OverloadedStrings #-}------data X = X---instance 'RowAlias' X where rowAliasName = const \"x\"------ \  ...---    r <- 'dbSelect' c $ addWhere_ \"bar.bar_key = x.bar_parent\" modelDBSelect---         :: IO [Bar :. As X Bar]--- @-newtype As alias row = As { unAs :: row }-instance (RowAlias alias, Show row) => Show (As alias row) where-  showsPrec d as@(As row) = showParen (d > 10) $ \rest ->-    "As " ++ S8.unpack (rowAliasName as) ++-    " (" ++ showsPrec 11 row (")" ++ rest)----- | @fromAs@ extracts the @row@ from an @'As' alias row@, but--- constrains the type of @alias@ to be the same as its first argument--- (which is non-strict).  This can save you from explicitly--- specifying types.  For example:------ > data X = X deriving (Generic)--- > instance RowAlias X where rowAliasName = const "x"--- >--- > ...--- >   r <- map (\(b1 :. b2) -> (b1, fromAs X b2)) <$>--- >       dbSelect c $ addWhere \"bar.bar_key = x.bar_parent\" modelDBSelect-fromAs :: alias -> As alias row -> row-{-# INLINE fromAs #-}-fromAs _ (As row) = row---- | A type-restricted wrapper around the 'As' constructor, under the--- same rationale as 'fromAs'.  Not strict in its first argument.-toAs :: alias -> row -> As alias row-{-# INLINE toAs #-}-toAs _ = As--aliasModelInfo :: forall a alias.-                  (Model a, RowAlias alias) =>-                  ModelInfo a -> ModelInfo (As alias a)-aliasModelInfo mi = r-  where alias = rowAliasName (undefined :: As alias a)-        r = mi { modelTable = alias-               , modelGetPrimaryKey = modelGetPrimaryKey mi . unAs-               }--aliasModelIdentifiers :: forall a alias. (Model a, RowAlias alias)-                      => ModelInfo a -> ModelIdentifiers (As alias a)-aliasModelIdentifiers mi-  | not ok    = error $ "aliasModelIdentifiers: degenerate model " ++-                show (modelQTable ida )-  | otherwise = r-  where r = ModelIdentifiers {-            modelQTable = S.concat [quoteIdent orig, " AS ", alias]-          , modelQColumns = qcols-          , modelQPrimaryColumn = qcols !! pki-          , modelQWriteColumns = deleteAt pki qcols-          , modelQualifier = Just alias-          , modelOrigTable = Just orig-          }-        ida = modelIdentifiers :: ModelIdentifiers a-        ok = Just (modelQTable ida) == modelQualifier ida-             && isJust (modelOrigTable ida)-        Just orig = modelOrigTable ida-        alias = quoteIdent $ rowAliasName (undefined :: As alias a)-        qcol c = S.concat [alias, ".", quoteIdent c]-        qcols = map qcol $ modelColumns mi-        pki = modelPrimaryColumn mi---- | A degenerate instance of 'Model' that re-names the row with a SQL--- @AS@ keyword.  This is primarily useful when joining a model with--- itself.  Hence, standard operations ('findRow', 'save', 'destroy')--- are not allowed on 'As' models.-instance (Model a, RowAlias as) => Model (As as a) where-  {-# INLINE modelInfo #-}-  modelInfo = aliasModelInfo modelInfo-  {-# INLINE modelRead #-}-  modelRead = As <$> modelRead-  modelWrite = error "attempt to write \"As\" alias as normal Model"-  {-# INLINE modelIdentifiers #-}-  modelIdentifiers = aliasModelIdentifiers modelInfo-  modelQueries = error "attempt to perform standard query on AS table alias"----- | Lookup the 'modelTable' of a 'Model' (@modelName _ = 'modelTable'--- ('modelInfo' :: 'ModelInfo' a)@).-modelName :: forall a. (Model a) => a -> S.ByteString-{-# INLINE modelName #-}-modelName _ = modelTable (modelInfo :: ModelInfo a)---- | Lookup the primary key of a 'Model'.-primaryKey :: (Model a) => a -> DBKey-{-# INLINE primaryKey #-}-primaryKey a = modelGetPrimaryKey modelInfo a---- | Generate a SQL @SELECT@ statement with no @WHERE@ predicate.  For--- example, 'defaultModelLookupQuery' consists of--- @modelSelectFragment@ followed by \"@WHERE@ /primary-key/ = ?\".-modelSelectFragment :: ModelIdentifiers a -> S.ByteString-modelSelectFragment mi = S.concat [- "SELECT ", S.intercalate ", " $ modelQColumns mi, " FROM ", modelQTable mi ]---- | A newtype wrapper in the 'FromRow' class, permitting every model--- to be used as the result of a database query.-newtype LookupRow a = LookupRow { lookupRow :: a } deriving (Show)-instance (Model a) => FromRow (LookupRow a) where-  fromRow = LookupRow <$> modelRead---- | A newtype wrapper in the 'ToRow' class, which marshalls every--- field except the primary key.  For use with 'modelInsertQuery'.-newtype InsertRow a = InsertRow a deriving (Show)-instance (Model a) => ToRow (InsertRow a) where-  toRow (InsertRow a) = modelWrite a---- | A newtype wrapper in the 'ToRow' class, which marshalls every--- field except the primary key, followed by the primary key.  For use--- with 'modelUpdateQuery'.-newtype UpdateRow a = UpdateRow a deriving (Show)-instance (Model a) => ToRow (UpdateRow a) where-  toRow (UpdateRow a) = toRow $ InsertRow a :. Only (primaryKey a)---- | Dump an entire model.  Useful for development and debugging only,--- as every row will be read into memory before the function returns.------ Note that unlike the other primary model operations, it is OK to--- call 'findAll' even on degenerate models such as 'As' and ':.'.-findAll :: forall r. (Model r) => Connection -> IO [r]-findAll c = action-  where mi = modelIdentifiers :: ModelIdentifiers r-        q = Query $ modelSelectFragment mi-        action = map lookupRow <$> query_ c q---- | Follow a 'DBRef' or 'DBRefUnique' and fetch the target row from--- the database into a 'Model' type @r@.-findRow :: forall r rt. (Model r) => Connection -> GDBRef rt r -> IO (Maybe r)-findRow c k = action-  where qs = modelQueries :: ModelQueries r-        action = do rs <- query c (modelLookupQuery qs) (Only k)-                    case rs of [r] -> return $ Just $ lookupRow $ r-                               _   -> return Nothing---- | Like 'trySave' but instead of returning an 'Either', throws a--- 'ValidationError' if the 'Model' is invalid.-save :: (Model r)-     => Connection -> r -> IO r-save c r = do-  eResp <- trySave c r-  case eResp of-    Right resp -> return resp-    Left  errs -> throwIO errs---- | 'save' but returning '()' instead of the saved model.-save_ :: (Model r)-      => Connection -> r -> IO ()-save_ c r = void $ save c r---- | Write a 'Model' to the database.  If the primary key is--- 'NullKey', the item is written with an @INSERT@ query, read back--- from the database, and returned with its primary key filled in.  If--- the primary key is not 'NullKey', then the 'Model' is written with--- an @UPDATE@ query and returned as-is.------ If the 'Model' is invalid (i.e. the return value of 'modelValid' is--- non-empty), a list of 'InvalidError' is returned instead.-trySave :: forall r. Model r-        => Connection -> r -> IO (Either ValidationError r)-trySave c r | not . H.null $ validationErrors errors = return $ Left errors-            | NullKey <- primaryKey r = do-                  rs <- query c (modelInsertQuery qs) (InsertRow r)-                  case rs of [r'] -> return $ Right $ lookupRow r'-                             _    -> fail "save: database did not return row"-            | otherwise = do-                  rows <- query c (modelUpdateQuery qs) (UpdateRow r)-                  case rows of [r'] -> return $ Right $ lookupRow r'-                               _     -> fail $ "save: database updated "-                                          ++ show (length rows)-                                          ++ " records"-  where qs = modelQueries :: ModelQueries r-        errors = modelValid r---- | Remove the row corresponding to a particular data structure from--- the database.  This function only looks at the primary key in the--- data structure.  It is an error to call this function if the--- primary key is not set.-destroy :: forall a. (Model a)-  => Connection -> a -> IO (Either ValidationError Bool)-destroy c a =-  case primaryKey a of-    NullKey -> fail "destroy: NullKey"-    DBKey k -> destroyByRef_ "destroy" c (DBRef k :: DBRef a)---- | Remove a row from the database without fetching it first.-destroyByRef :: forall a rt. (Model a)-  => Connection -> GDBRef rt a -> IO (Either ValidationError Bool)-destroyByRef = destroyByRef_ "destroyByRef"--destroyByRef_ :: forall a rt. (Model a)-  => T.Text -> Connection -> GDBRef rt a -> IO (Either ValidationError Bool)-destroyByRef_ msg c a = action-  where mq     = modelQueries     :: ModelQueries a-        mi     = modelIdentifiers :: ModelIdentifiers a-        pkCol  = modelQPrimaryColumn mi-        action = do-            n <- execute c (modelDeleteQuery mq) (Only a)-            return $ case n of-                0 -> Right False-                1 -> Right True-                _ -> Left $ validationError (T.decodeUtf8 pkCol) $-                    msg <> ": DELETE modified " <> T.pack (show n) <>-                    " rows. This may indicate that your primary key" <>-                    " accessor field is not actually a primary key."---- | Print to stdout the query statement.-printq :: Query -> IO ()-printq (Query bs) = S8.putStrLn bs-
− Database/PostgreSQL/ORM/SqlType.hs 
@@ -1,108 +0,0 @@-{-# LANGUAGE CPP #-}-{-# LANGUAGE FlexibleInstances #-}-{-# LANGUAGE OverloadedStrings #-}-{-# LANGUAGE ScopedTypeVariables #-}--module Database.PostgreSQL.ORM.SqlType (SqlType(..), getTypeOid) where--import qualified Data.ByteString as S-import qualified Data.ByteString.Lazy as L-import Data.Int-import Data.Monoid-import qualified Data.Text as ST-import qualified Data.Text.Lazy as LT-import Data.Time-import Data.Typeable-import qualified Data.Vector as V-import Database.PostgreSQL.Simple-import Database.PostgreSQL.Simple.FromField-import Database.PostgreSQL.Simple.Time-import Database.PostgreSQL.Simple.ToField-import Database.PostgreSQL.Simple.TypeInfo.Static-import Database.PostgreSQL.Simple.Types--import Database.PostgreSQL.ORM.Model--newtype ExtractTypeOid = ExtractTypeOid Oid-instance FromField ExtractTypeOid where-  fromField f _ = return $ ExtractTypeOid $ typeOid f---- | Retreive the 'Oid' corresponding to a type.  You can subsequently--- use the 'Oid' to call 'getTypeInfo' for more information on the--- type.-getTypeOid :: Connection -> S.ByteString -> IO Oid-getTypeOid c tname = do-  [Only (ExtractTypeOid ti)] <- query_ c $ Query $ "SELECT NULL :: " <> tname-  return ti---- | The class of Haskell types that can be converted to and from a--- particular SQL type.  For most instances, you only need to define--- 'sqlBaseType'.-class (ToField a, FromField a) => SqlType a where-  sqlBaseType :: a -> S.ByteString-  -- ^ The name of the SQL type corresponding to Haskell type @a@,-  -- when a value of @a@ can be null.  This is the SQL type to and-  -- from which a @'Maybe' a@ will be converted (where 'Nothing'-  -- corresponds to the SQL value null).-  sqlType :: a -> S.ByteString-  -- ^ The name of the SQL type corresponding to Haskell type @a@,-  -- when @a@ is not wrapped in 'Maybe' and hence cannot be null.  If-  -- @sqlType@ is unspecified, the default is to append \"@NOT NULL@\"-  -- to 'sqlBaseType'.-  {-# INLINE sqlType #-}-  sqlType _ = (sqlBaseType (undefined :: a)) <> " NOT NULL"--#define TYPE(hs, sql) \-    instance SqlType (hs) where sqlBaseType _ = typname (sql)-TYPE(Bool, bool)-TYPE(Double, float8)-TYPE(Float, float4)-TYPE(Int16, int2)-TYPE(Int32, int4)-TYPE(Int64, int8)-TYPE(S.ByteString, text)-TYPE(L.ByteString, text)-TYPE(ST.Text, text)-TYPE(LT.Text, text)-TYPE(Oid,oid)-TYPE(LocalTime, timestamp)-TYPE(ZonedTime, timestamptz)-TYPE(TimeOfDay, time)-TYPE(UTCTime, timestamptz)-TYPE(Day, date)-TYPE(Date, date)-TYPE(ZonedTimestamp, timestamptz)-TYPE(UTCTimestamp, timestamptz)-TYPE(LocalTimestamp, timestamp)-TYPE(String, text)-TYPE(Binary S.ByteString, bytea)-TYPE(Binary L.ByteString, bytea)--#undef TYPE--instance SqlType DBKey where-  sqlType _ = "bigserial UNIQUE NOT NULL PRIMARY KEY"-  sqlBaseType _ = error "DBKey should not be wrapped in type"--instance (SqlType a) => SqlType (Maybe a) where-  sqlType _ = sqlBaseType (undefined :: a)-  sqlBaseType _ = error "Table field Maybe should not be wrapped in other type"--instance (Typeable a, SqlType a) => SqlType (V.Vector a) where-  sqlBaseType _ = sqlBaseType (undefined :: a) <> "[]"--instance (Model a) => SqlType (DBRef a) where-  sqlBaseType (DBRef k) = sqlBaseType k <> ref-    where t = modelInfo :: ModelInfo a-          Just orig = modelOrigTable (modelIdentifiers :: ModelIdentifiers a)-          ref = S.concat [-              " REFERENCES ", quoteIdent orig, "("-              , quoteIdent (modelColumns t !! modelPrimaryColumn t), ")" ]--instance (Model a) => SqlType (DBRefUnique a) where-  sqlBaseType (DBRef k) = sqlBaseType k <> ref-    where t = modelInfo :: ModelInfo a-          Just orig = modelOrigTable (modelIdentifiers :: ModelIdentifiers a)-          ref = S.concat [-              " UNIQUE REFERENCES ", quoteIdent orig , "("-              , quoteIdent (modelColumns t !! modelPrimaryColumn t), ")" ]
− Database/PostgreSQL/ORM/Validations.hs 
@@ -1,49 +0,0 @@-{-# LANGUAGE CPP, FlexibleContexts, DeriveDataTypeable, OverloadedStrings #-}-module Database.PostgreSQL.ORM.Validations where--import Control.Exception-import Data.Aeson-import qualified Data.HashMap.Strict as H-#if __GLASGOW_HASKELL__ < 710-import Data.Monoid-#endif-import qualified Data.Text as T-import Data.Typeable--newtype ValidationError = ValidationError-  { validationErrors :: H.HashMap T.Text [T.Text] } deriving (Show, Typeable)--instance Exception ValidationError--instance Monoid ValidationError where-  mempty = ValidationError mempty-  mappend ein zwei = ValidationError $!-    H.unionWith mappend (validationErrors ein) (validationErrors zwei)--instance ToJSON ValidationError where-  toJSON = toJSON . validationErrors--instance FromJSON ValidationError where-  parseJSON val = ValidationError `fmap` parseJSON val--type ValidationFunc a = a -> ValidationError--validationError :: T.Text -> T.Text -> ValidationError-validationError columnName description =-    ValidationError $ H.singleton columnName [description]--validate :: (a -> Bool)-         -> T.Text -- ^ Column name-         -> T.Text -- ^ Error description-         -> ValidationFunc a-validate validator columnName desc = \a ->-  if validator a-    then mempty-    else validationError columnName desc--validateNotEmpty :: (a -> T.Text)-                 -> T.Text-                 -> T.Text-                 -> ValidationFunc a-validateNotEmpty accessor = validate (not . T.null . accessor)-
pg_migrate.hs view
@@ -1,6 +1,6 @@ import Database.PostgreSQL.Migrate import System.Environment-import System.Exit +import System.Exit import System.FilePath import System.IO @@ -19,9 +19,12 @@     "new":name:[] -> newMigration name defaultMigrationsDir >>                       return ExitSuccess     "new":name:dir:[] -> newMigration name dir >> return ExitSuccess+    "compile":out:[] -> compileMigrationsForDir defaultMigrationsDir out+    "compile":out:dir:[] -> compileMigrationsForDir dir out     _ -> do       progName <- getProgName       putStrLn $ "Usage: " ++ progName ++ " migrate|rollback [DIRECTORY]"+      putStrLn $ "       " ++ progName ++ " compile [PROGRAM] [DIRECTORY]"       putStrLn $ "       " ++ progName ++ " init"       putStrLn $ "       " ++ progName ++ " dump [FILE]"       putStrLn $ "       " ++ progName ++ " new NAME [DIRECTORY]"@@ -29,4 +32,3 @@   if ec == ExitSuccess then     return ()     else exitWith ec-
postgresql-orm.cabal view
@@ -1,5 +1,5 @@ name: postgresql-orm-version: 0.5.0+version: 0.5.1 cabal-version: >= 1.14 build-type: Simple license: GPL@@ -8,7 +8,7 @@ maintainer: amit@amitlevy.com category: Database synopsis: An ORM (Object Relational Mapping) and migrations DSL for PostgreSQL.-data-files: man/man1/pg_migrate.1 man/man5/pg_migrate.5 static/migration.hs+data-files: man/man1/pg_migrate.1 man/man5/pg_migrate.5 static/migration.hs static/CompilerUtils.hs description:   An ORM (Object Relational Mapping) and migrations DSL for PostgreSQL. See   "Database.PostgreSQL.ORM" for documentation.@@ -16,21 +16,14 @@ executable pg_migrate   default-language: Haskell2010   Main-is: pg_migrate.hs+  hs-source-dirs: .   ghc-options: -Wall   build-depends: base < 6-               , blaze-builder >= 0.4-               , bytestring-               , bytestring-builder-               , directory+               , postgresql-orm                , filepath-               , ghc-prim-               , mtl-               , old-locale-               , postgresql-simple >= 0.4.1.0-               , process-               , time  library+  hs-source-dirs: src   default-language: Haskell2010   build-depends: base < 6                , aeson@@ -40,10 +33,12 @@                , directory                , filepath                , ghc-prim+               , haskell-src-exts                , mtl                , old-locale                , postgresql-simple                , process+               , temporary                , text                , time                , transformers@@ -79,4 +74,3 @@ source-repository  head   type:         git   location:     https://github.com/alevy/postgresql-orm.git-
+ src/Data/GetField.hs view
@@ -0,0 +1,247 @@+{-# LANGUAGE Safe #-}+{-# LANGUAGE CPP #-}+{-# LANGUAGE DefaultSignatures #-}+{-# LANGUAGE FlexibleContexts #-}+{-# LANGUAGE FlexibleInstances #-}+{-# LANGUAGE FunctionalDependencies #-}+{-# LANGUAGE MultiParamTypeClasses #-}+#if __GLASGOW_HASKELL__ < 710+{-# LANGUAGE OverlappingInstances #-}+#endif+{-# LANGUAGE RankNTypes #-}+{-# LANGUAGE AllowAmbiguousTypes #-}+{-# LANGUAGE TypeOperators #-}+{-# LANGUAGE UndecidableInstances #-}++-- | Functions to extract a field of a particular type from a+-- 'Generic' data structure, when the data structure contains exactly+-- one field of the given type.  Only works for types with exactly one+-- constructor (not variant types).+--+-- An example of usage:+--+-- > data MyType = MyType { myString :: String             -- position 0+-- >                      , myInt :: Int                   -- position 1+-- >                      , myBool :: Bool                 -- position 2+-- >                      , myMaybeChar :: Maybe Char      -- position 3+-- >                      , myMaybeString :: Maybe String  -- position 4+-- >                      } deriving (Show, Generic)+-- > +-- > myType :: MyType+-- > myType = MyType "my type" 21 True Nothing (Just "maybe string")+--+-- >>> getFieldVal ExtractId myType :: String+-- "my type"+-- >>> getFieldVal ExtractId myType :: Int+-- 21+-- >>> getFieldVal ExtractMaybe myType :: Maybe Char+-- Nothing+-- >>> getFieldVal ExtractMaybe myType :: Maybe Int+-- Just 21+-- >>> getFieldVal ExtractMaybe myType :: Maybe String  -- ambiguous+-- <interactive>:5:1: Couldn't match type `THasMany' with `THasOne'+-- >>> getFieldPos' ExtractId (undefined :: MyType) (undefined :: Bool)+-- 2+-- >>> getFieldPos' ExtractMaybe (undefined :: MyType) (undefined :: Maybe Bool)+-- 2+-- >>> getFieldPos' ExtractMaybe myType ()  -- No field has type ()+-- <interactive>:8:1: Couldn't match type `THasNone' with `THasOne'+module Data.GetField (+  GetField(..), ExtractId(..), ExtractMaybe(..), getFieldPos'+  -- * Internals+  , THasOne(..), THasNone(..), THasMany(..), Extractor(..), GGetField(..)+  ) where++import GHC.Generics++-- | Dirty trick to construct "less specific" overlapping instances by+-- making a class argument a simple type variable, but constraining+-- that variable to be a particular type.  E.g., neither of the+-- following two instances is more specific than the other, because+-- @NO@ is not more general than @YES@:+--+-- > class MyClass a b c | a b -> c where myClass :: a -> b -> c ()+-- > instance MyClass a a YES       where myClass _ _ = YES ()+-- > instance MyClass a b NO        where myClass _ _ = NO ()+--+-- Hence, attempting to use the first instance will generate a+-- compilation error rather than inferring the type of c as YES.  On+-- the other hand, of the following two instances, the first is more+-- specific than the second:+--+-- > instance MyClass a a YES where+-- >     myClass _ _ = YES ()+-- > instance (TypeGCast NO c) => MyClass a b c where+-- >     myClass _ _ = typeGCast $ NO ()+--+-- That's because @c@ is more general than @YES@.  The key to this+-- working is that an instance context--i.e., @(TypeGCast NO c)@--is+-- never consulted during instance selection, only to validate an+-- already-selected most-specific instance.+--+-- Note that @YES@ and @NO@ in these examples have kind @* -> *@.+-- Hence the @G@ in @TypeGCast@.  The same trick is equally applicable+-- to types of kind @*@, we just don't happen to need that in this+-- module.+class TypeGCast f g | f -> g where+  typeGCast :: f p -> g p+instance TypeGCast f f where+  typeGCast = id++-- | Exactly one matching field has been found.+newtype THasOne a = THasOne { fromTHasOne :: a } deriving (Show)+-- | Zero matching fields have been found.+data THasNone a = THasNone deriving (Show)+-- | More than one matching field has been found.+newtype THasMany a = THasMany { fromTHasMany :: [a] } deriving (Show)++class GCombine a b c | a b -> c where+  gCombine :: a p -> b p -> c p+instance GCombine THasOne THasNone THasOne where+  {-# INLINE gCombine #-}+  gCombine j _ = j+instance GCombine THasNone THasOne THasOne where+  {-# INLINE gCombine #-}+  gCombine _ j = j+instance GCombine THasNone THasNone THasNone where+  -- Should never be evaluated, so no need to inline it+  gCombine _ _ = THasNone+instance GCombine THasOne THasOne THasMany where+  {-# INLINE gCombine #-}+  gCombine (THasOne a) (THasOne b) = THasMany [a,b]+instance GCombine THasMany THasMany THasMany where+  {-# INLINE gCombine #-}+  gCombine (THasMany as) (THasMany bs) = THasMany (as ++ bs)+instance GCombine THasNone THasMany THasMany where+  {-# INLINE gCombine #-}+  gCombine _ hm = hm+instance GCombine THasMany THasNone THasMany where+  {-# INLINE gCombine #-}+  gCombine hm _ = hm+instance GCombine THasOne THasMany THasMany where+  {-# INLINE gCombine #-}+  gCombine (THasOne a) (THasMany as) = THasMany (a:as)+instance GCombine THasMany THasOne THasMany where+  {-# INLINE gCombine #-}+  gCombine (THasMany as) (THasOne a) = THasMany (as++[a])++class GCount f where gCount :: f p -> (Int, [Int])+instance GCount THasOne where gCount  _ = (1, [0])+instance GCount THasMany where gCount _ = (1, [0])+instance GCount THasNone where gCount _ = (1, [])++-- | Class of types used as tag arguments to 'gGetFieldVal' and+-- 'gGetFieldPos'.  @f@ should be a new unit type of kind @* -> *@,+-- used to designate the type of extraction you want.  Then instances+-- should be defined to transform each type @a@ you want to extract to+-- some type @r@, with @g@ set to 'THasOne'.+--+-- For example, 'ExtractMaybe' is a type to convert types @a@ and+-- @Maybe a@ both to type @Maybe a@ (i.e., type argument @r@ is @Maybe+-- a@).+--+-- > data ExtractMaybe a = ExtractMaybe+-- > instance Extractor ExtractMaybe a (Maybe a) THasOne where+-- >   extract _ = THasOne . Just+-- > instance Extractor ExtractMaybe (Maybe a) (Maybe a) THasOne where+-- >   extract _ = THasOne+--+-- Note that there is already a default general instance returning+-- 'THasNone'.  Hence, you do not need to define one.  Otherwise, you+-- would have to define an overlapping instance such as:+--+-- > instance Extractor ExtractMaybe a b THasZero where  -- Incorrect+-- >   extract _ = THasNone+--+-- (Except the above wouldn't quite work anyway given the rules for+-- overlapping instances.)  So just assume that any instance you don't+-- explicitly define for your 'Extractor' will automatically fall back+-- to 'THasNone'.+class Extractor f a r g | f a r -> g where+  extract :: f r -> a -> g r+  extractCount :: f r -> a -> (Int, [Int])+  default extractCount :: (GCount g) => f r -> a -> (Int, [Int])+  extractCount fr a = gCount (extract fr a)+instance+  {-# OVERLAPPABLE #-}+  (TypeGCast THasNone g) => Extractor f a r g where+  extract _ _ = typeGCast THasNone+  extractCount _ _ = gCount THasNone++-- | Generlized extraction of a field from a 'Generic' data structure.+-- Argument @rep@ should generally be the type @'Rep' t@ for some data+-- type @t@ whose fields you want to extract.  @r@ is the result type+-- you want back from the extraction.  @f@ should be defined such that+-- there is an instance of @'Extractor' f a r THasOne@ for each type+-- @a@ you want to convert to @r@ and extract.+class GGetField f rep r g | f rep r -> g where+  gGetFieldVal :: f r -> rep p -> g r+  -- ^ Returns zero, one, or multiple values of type @f@ wrapped in+  -- 'THasOne', 'THasNone', or 'THasMany' respectively.+  gGetFieldPos :: f r -> rep p -> (Int, [Int])+  -- ^ Returns @(total, positions)@ where @total@ is the total number+  -- of fields (matching or not) in the structure and @positions@ is a+  -- list of zero-based field numbers of the fields matching target+  -- type @f r@.+instance (Extractor f c r g) => GGetField f (K1 i c) r g where+  {-# INLINE gGetFieldVal #-}+  gGetFieldVal f (K1 c) = extract f c+  gGetFieldPos f (K1 c) = extractCount f c+instance (GGetField f a1 r g1, GGetField f a2 r g2, GCombine g1 g2 g) =>+         GGetField f (a1 :*: a2) r g where+           {-# INLINE gGetFieldVal #-}+           gGetFieldVal f (a1 :*: a2) =+             gCombine (gGetFieldVal f a1) (gGetFieldVal f a2)+           gGetFieldPos f ~(a1 :*: a2) = (n1 + n2, p1 ++ map (n1 +) p2)+             where (n1, p1) = gGetFieldPos f a1+                   (n2, p2) = gGetFieldPos f a2+instance (GGetField f a r g) => GGetField f (M1 i c a) r g where+  {-# INLINE gGetFieldVal #-}+  gGetFieldVal f (M1 a) = gGetFieldVal f a+  gGetFieldPos f ~(M1 a) = gGetFieldPos f a+++class (Generic a, GGetField f (Rep a) r THasOne) => GetField f a r where+  -- | Extract the single field matching 'Extractor' @f r@ from a+  -- 'Generic' data structure @a@ with exactly one constructor.+  getFieldVal :: f r -> a -> r+  -- | Extract the 0-based position of the single field matching+  -- 'Extractor' @f r@ within 'Generic' data structure @a@.+  -- Non-strict in both arguments.+  getFieldPos :: f r -> a -> Int+instance (Generic a, GGetField f (Rep a) r THasOne) => GetField f a r where+  {-# INLINE getFieldVal #-}+  getFieldVal f a = fromTHasOne $ gGetFieldVal f (from a)+  getFieldPos f a = head $ snd $ gGetFieldPos f (from a)++-- | A variant of 'getFieldPos' in which the type of the field is+-- supplied as a non-strict argument.  This may be easier than+-- typecasting the extractor argument.  For example, to extract the+-- 'Int' from a structure with a single 'Int' field:+--+-- @+--       getFieldPos' 'ExtractId' myStruct ('undefined' :: 'Int')+-- @+getFieldPos' :: (Generic a, GGetField f (Rep a) r THasOne) =>+                (f ()) -> a -> r -> Int+getFieldPos' f a r = getFieldPos (fixType f r) a+  where fixType :: f () -> r -> f r+        fixType _ _ = undefined++-- | An extractor that matches an exact field type.+data ExtractId r = ExtractId deriving (Show)+instance Extractor ExtractId a a THasOne where+  {-# INLINE extract #-}+  extract _ = THasOne++-- | An extractor that matches either type @r@ or type @Maybe r@, and,+-- in the former case, wraps @Just@ around the value so as always to+-- return type @Maybe r@.+data ExtractMaybe r = ExtractMaybe+instance Extractor ExtractMaybe a (Maybe a) THasOne where+  {-# INLINE extract #-}+  extract _ = THasOne . Just+instance Extractor ExtractMaybe (Maybe a) (Maybe a) THasOne where+  {-# INLINE extract #-}+  extract _ = THasOne+
+ src/Data/RequireSelector.hs view
@@ -0,0 +1,28 @@+{-# LANGUAGE FlexibleInstances, UndecidableInstances, CPP #-}++module Data.RequireSelector (RequireSelector) where++#if defined(__GLASGOW_HASKELL__) && (__GLASGOW_HASKELL__ < 800)+import GHC.Generics++-- | There are intentionally no members of this class, so that placing+-- it in a context will always cause an error.+class IntentionallyCauseError a+#endif++-- | The point of this class is to ensure that you are using data+-- types defined with record selectors (i.e., @data Foo = Foo { unFoo+-- :: Int }@ as opposed to @data Foo = Foo Int@).+--+-- Unfortunately, "GHC.Generics" makes the 'NoSelector' type a member+-- of the 'Selector' class.  Hence, if you want to ensure a type @a@+-- is /not/ 'NoSelector', use the context @(RequireSelector a) =>@.+--+-- If you see a compilation error involving @RequireSelector@ or+-- @IntentionallyCauseError@, it means you failed to define one of+-- your datatypes using record selector syntax.+class RequireSelector a+#if defined(__GLASGOW_HASKELL__) && (__GLASGOW_HASKELL__ < 800)+instance (IntentionallyCauseError NoSelector) => RequireSelector NoSelector+#endif+instance RequireSelector a
+ src/Database/PostgreSQL/Describe.hs view
@@ -0,0 +1,86 @@+{-# LANGUAGE OverloadedStrings #-}++-- | Utility function for describing a table in the database.+module Database.PostgreSQL.Describe (+  ColumnInfo(..), describeTable+  ) where++import Control.Monad+import qualified Data.ByteString as S+import Data.Int+import qualified Data.Vector as V+import qualified Database.PostgreSQL.Simple.TypeInfo.Static as PG+import Database.PostgreSQL.Simple+import Database.PostgreSQL.Simple.TypeInfo+import Database.PostgreSQL.Simple.Types++data ColumnInfo = ColumnInfo {+    colNum :: !Int16+    -- ^ Internal column number used by PostgreSQL.  Generally these+    -- will be consecutive starting from 1, but this may not be the+    -- case if you have altered a table to delete columns.+  , colName :: S.ByteString+    -- ^ Name of the column+  , colType :: !TypeInfo+    -- ^ Type of the column+  , colNotNull :: !Bool+    -- ^ If 'True', the database cannot contain null.  (This+    -- constraint should always be accurate.)+  , colPrimary :: !Bool+    -- ^ 'True' if this column (and only this column) constitutes the+    -- primary key of the table.  Always 'False' if the primary key+    -- comprises multiple columns (even if this is one of those+    -- columns).+  , colUnique :: !Bool+    -- ^ 'True' if there is a uniqueness constraint on this column.+    -- Not 'True' if this column is part of a uniqueness constraint+    -- involving multiple columns.  (Such multi-column uniqueness+    -- constraints are not reported by this interface.)+  , colReferences :: !(Maybe S.ByteString)+    -- ^ If this there is a foreign key constraint on this column (and+    -- the constraint does not span multiple columns), report the+    -- table referenced by this column.+  } deriving (Show)++defColInfo :: ColumnInfo+defColInfo = ColumnInfo {+    colNum = 0+  , colName = S.empty+  , colType = PG.void+  , colNotNull = False+  , colPrimary = False+  , colUnique = False+  , colReferences = Nothing+  }++-- | Returns a list of 'ColumnInfo' structures for a particular table.+-- Not all information about a table is returned.  In particular,+-- constraints that span columns are ignored.+describeTable :: Connection -> S.ByteString -> IO [ColumnInfo]+describeTable cn t = do+  [(Only tbloid)] <- query cn "select oid from pg_class where relname = ?"+                     (Only t)+  cs0 <- query cn "select attnum, attname, atttypid, attnotnull\+                  \ from pg_attribute\+                  \ where attrelid = ? and attisdropped = 'f' and attnum > 0\+                  \ order by attnum"+                  (Only (tbloid :: Oid))+  cs1 <- forM cs0 $ \ (num, name, typ, notnull) -> do+    ti <- getTypeInfo cn typ+    return defColInfo {+      colNum = num, colName = name, colType = ti, colNotNull = notnull+    }+  constraints <- query cn "select contype, conkey, relname\+                          \ from pg_constraint left join pg_class\+                          \ on confrelid = pg_class.oid\+                          \ where conrelid = ?"+                          (Only tbloid)+  let _ = constraints :: [(String, V.Vector Int16, Maybe S.ByteString)]+  return $ map (\c -> foldl appConstr c constraints) cs1+    where appConstr ci (ct, ck, mn)+            | V.length ck == 1, colNum ci == ck V.! 0 = appConstr1 ci ct mn+            | otherwise                           = ci+          appConstr1 ci "p" _ = ci { colPrimary = True }+          appConstr1 ci "u" _ = ci { colUnique = True }+          appConstr1 ci "f" n@(Just _) = ci { colReferences = n }+          appConstr1 ci _ _ = ci
+ src/Database/PostgreSQL/Devel.hs view
@@ -0,0 +1,218 @@+{-# LANGUAGE CPP #-}+{-# LANGUAGE OverloadedStrings #-}++-- | Functions for initializing self-contained local postgreSQL+-- database clusters (useful in development more than production).+module Database.PostgreSQL.Devel (+      createLocalDB, configLocalDB, startLocalDB+    , initLocalDB, stopLocalDB, setLocalDB+    , withTempDB+    , resetConnection+  ) where++import Control.Exception+import Control.Monad+#if __GLASGOW_HASKELL__ < 710+import Data.Functor+#endif+import Data.List+import Database.PostgreSQL.Simple+import System.Directory+import System.Exit+import System.FilePath+import System.IO+import System.IO.Error+import System.Posix.Env+import System.Posix.Temp+import System.Process++isNonEmptyDir :: FilePath -> IO Bool+isNonEmptyDir dir =+  catchJust (\e -> if isDoesNotExistError e then Just () else Nothing)+  ((> 2) . length <$> getDirectoryContents dir)+  (const $ return False)++addDirectives :: [(String, String)] -> [String] -> [String]+addDirectives directives [] = map snd directives+addDirectives directives (cl:cls)+  | Just l <- lookup directive directives =+      (if comment then [l, cl] else [l]) +++      addDirectives (directives \\ [(directive,l)]) cls+  | otherwise = cl : addDirectives directives cls+  where (comment, directive)+          | '#':clr <- cl, [(d,_)] <- lex clr = (True, d)+          | [(d,_)] <- lex cl                 = (False, d)+          | otherwise                         = (False, "")++-- | Set configuration parameters on a database by editing the+-- @postgresql.conf@ file.  Takes the database directory and a list of+-- @(@/parameter/@,@ /full-line/@)@ pairs.  For example, when creating+-- a throw-away database cluster you later intend to discard, you+-- might say:+--+-- > configLocalDB dbpath [("fsync", "fsync = off")]+--+-- Note that the second element of each pair is the complete+-- configuration line.  It is not correct to say:+--+-- > configLocalDB dbpath [("fsync", "off")]   -- INCORRECT+--+configLocalDB :: FilePath -> [(String, String)] -> IO ()+configLocalDB dir directives = do+  let confpath = dir </> "postgresql.conf"+  oldconf <- lines <$> readFile confpath+  let conf = unlines $ addDirectives directives oldconf+  length conf `seq` writeFile confpath conf++singleQuote :: String -> String+singleQuote ('\'':t) = "''" ++ singleQuote t+singleQuote (h:t)    = h : singleQuote t+singleQuote []       = ""++pgDirectives :: FilePath -> [(String, String)]+pgDirectives dir = [+    ("unix_socket_directories"+    , "unix_socket_directories = '" ++ singleQuote dir ++ "'")+  , ("logging_collector",  "logging_collector = yes")+  , ("listen_addresses", "listen_addresses = ''")]++pgDirectives92 :: FilePath -> [(String, String)]+pgDirectives92 dir = map depluralize $ pgDirectives dir+  where depluralize ("unix_socket_directories", _) =+          ("unix_socket_directory"+          , "unix_socket_directory = '" ++ singleQuote dir ++ "'")+        depluralize kv = kv++-- | Create a directory for a local database cluster entirely+-- self-contained within one directory.  This is accomplished by+-- creating a new PostgreSQL database cluster in the directory and+-- setting the following configuration options in @postgresql.conf@:+--+-- * @listen_address@ is set to empty (i.e., @\'\'@), so that no TCP+-- socket is bound, avoiding conflicts with any other running instaces+-- of PostgreSQL.+--+-- * @logging_collector@ is set to @yes@, so that all message logs are+--   kept in the @pg_log@ subdirectory of the directory you specified.+--+-- Note this function does /not/ start a postgres server after+-- creating the directory.  You will seperately need to start the+-- server using 'startLocalDB' or 'initLocalDB'.  (And note that+-- 'initLocalDB' already calls @createLocalDB@ if the directory does+-- not exist or is empty.  Hence the primary use of this function is+-- if you want to call 'configLocalDB' between 'createLocalDB' and+-- 'startLocalDB'.)+createLocalDB :: FilePath -> IO ()+createLocalDB dir = do+  (exit, _, err) <- readProcessWithExitCode "pg_ctl"+                      ["-D", dir, "-o", "--no-locale", "init"] ""+  when (exit /= ExitSuccess) $ fail err+  dir' <- canonicalizePath dir+  writeFile (dir </> "README_BEFORE_DELETING") $+    "## IMPORTANT:  Run the following command before deleting this " +++    "directory ##\n\n" +++    "pg_ctl -D " ++ showCommandForUser dir' [] ++ " stop -m immediate\n\n"+  version <- readFile (dir </> "PG_VERSION")+  case reads version of+    [(v, _)] | v < (9.3 :: Double) -> configLocalDB dir $ pgDirectives92 dir'+    _                              -> configLocalDB dir $ pgDirectives dir'++systemNoStdout :: String -> [String] -> IO ExitCode+systemNoStdout prog args =+  bracket (openFile "/dev/null" ReadWriteMode) hClose $ \devnull -> do+    let cp = (proc prog args) { std_in = UseHandle devnull+                              , std_out = UseHandle devnull }+    (_,_,_,pid) <- createProcess cp+    waitForProcess pid++-- | Start a local database if the server is not already running.+-- Otherwise, does nothing, but returns a 'ConnectInfo' in either+-- case.  The database server will continue running after the current+-- process exits (but see 'stopLocalDB').+startLocalDB :: FilePath -> IO ConnectInfo+startLocalDB dir0 = do+  dir <- canonicalizePath dir0+  (e0, _, _) <- readProcessWithExitCode "pg_ctl" ["status", "-D", dir] ""+  when (e0 /= ExitSuccess) $ do+    e1 <- systemNoStdout "pg_ctl" [ "start", "-w", "-D", dir ]+    when (e1 /= ExitSuccess) $ fail "could not start postgres"+  return defaultConnectInfo { connectHost = dir+                            , connectUser = ""+                            , connectDatabase = "postgres"+                            }++-- | A combination of 'createLocalDB' and 'startLocalDB'.+--+-- The parameter is a PostgreSQL data directory.  If the directory is+-- empty or does not exist, this function creates a new database+-- cluster (via 'createLocalDB').  Then, if a database server is not+-- already running for the directory, starts a server.  No matter+-- what, returns a 'ConnectInfo' that will connect to the server+-- running on this local database.+--+-- Note that if @initLocalDB@ starts a postgres server, the server+-- process will continue running after the process that called+-- @initLocalDB@ exits.  This is normally fine.  Since multiple client+-- processes may access the same PostgreSQL database, it makes sense+-- for the first client to start the database and no one to stop it.+-- See 'stopLocalDB' if you wish to stop the server process (which you+-- should always do before deleting a test cluster).  See also+-- 'withTempDB' to create a temporary cluster for the purposes of+-- running a test suite.+initLocalDB :: FilePath -> IO ConnectInfo+initLocalDB dir = do+  exists <- isNonEmptyDir dir+  unless exists $ createLocalDB dir+  startLocalDB dir++-- | Stop the server for a local database cluster entirely+-- self-contained within one directory.  You must call this before+-- deleting the directory, or else stray postgres processes will+-- linger forever.  If the argument is the empty string, looks for the+-- database directory in the @PGDATA@ environment variable.+stopLocalDB :: FilePath -> IO ()+stopLocalDB dir0 = do+  dir <- if not (null dir0) then return dir0 else do+    mpgd <- getEnv "PGDATA"+    case mpgd of Just pgd -> return pgd+                 _        -> fail "stopLocalDB: must specify database"+  e <- systemNoStdout "pg_ctl" ["stop", "-D", dir, "-m", "fast"]+  when (e /= ExitSuccess) $ fail "could not stop postgres"++-- | Set environment variables to make a local database cluster the+-- default.  Also returns shell commands you can eval or cut-and-paste+-- into your shell to make @pg_ctl@ and @psql@ access a local database+-- cluster.+setLocalDB :: FilePath -> IO String+setLocalDB dir0 = do+  dir1 <- canonicalizePath dir0+  setEnv "PGHOST" dir1 True+  setEnv "PGDATA" dir1 True+  setEnv "PGDATABASE" "postgres" True+  let dir = showCommandForUser dir1 []+  msh <- getEnv "SHELL"+  return $ case msh of Just sh | isSuffixOf "csh" sh ->+                         "setenv PGDATA " ++ dir ++ "; setenv PGHOST " ++ dir+                       _ -> "export PGDATA=" ++ dir ++ " PGHOST=" ++ dir++-- | Run a function with a completely fresh database cluster that gets+-- deleted on return.  Since the entire database is blown away when+-- the function returns, @withTempDB@ is obviously only useful for+-- test suites.+withTempDB :: (ConnectInfo -> IO a) -> IO a+withTempDB f = bracket createdir removeDirectoryRecursive $ \d ->+  flip finally (stopLocalDB d) $ do+    createLocalDB d+    configLocalDB d [("fsync", "fsync = off")+                    , ("synchronous_commit", "synchronous_commit = off")+                    , ("full_page_writes", "full_page_writes = off")]+    initLocalDB d >>= f+  where createdir = do+          tmp <- getTemporaryDirectory+          mkdtemp $ tmp </> "db."++-- | Reset a connection to its default state before re-cycling it for+-- another thread or request.+resetConnection :: Connection -> IO ()+resetConnection c = (void $ execute_ c "DISCARD ALL") `catch` \SqlError{} ->+  void $ execute_ c "ROLLBACK" >> execute_ c "DISCARD ALL"
+ src/Database/PostgreSQL/Escape.hs view
@@ -0,0 +1,269 @@+{-# LANGUAGE Trustworthy #-}+{-# LANGUAGE BangPatterns #-}+{-# LANGUAGE MagicHash #-}+{-# LANGUAGE OverloadedStrings #-}+{-# LANGUAGE UnboxedTuples #-}+{-# LANGUAGE CPP #-}++#include "MachDeps.h"++-- | This module deals with escaping and sanitizing SQL templates.+module Database.PostgreSQL.Escape (+    fmtSql, quoteIdent+  , buildSql, buildSqlFromActions+  , buildAction, buildLiteral, buildByteA, buildIdent+  ) where++import Blaze.ByteString.Builder.Internal.Write+import Data.ByteString.Builder+import Data.ByteString.Builder.Internal+import Data.ByteString.Lazy (toStrict)+import qualified Data.ByteString as S+import qualified Data.ByteString.Internal as S+import qualified Data.ByteString.Unsafe as S+import Data.Monoid+import Database.PostgreSQL.Simple+import Database.PostgreSQL.Simple.ToField+import Database.PostgreSQL.Simple.ToRow+import Database.PostgreSQL.Simple.Types+import Foreign.Marshal.Alloc (mallocBytes)+import Foreign.Storable (pokeByteOff)+import GHC.Prim (Addr#, and#, geAddr#, geWord#, Int#, int2Word#+                , minusAddr#, ord# , plusAddr#, readWord8OffAddr#+                , State# , uncheckedShiftRL#, word2Int#, writeWord8OffAddr#+                , Word#)+import GHC.Ptr (Ptr(Ptr))+import GHC.Types (Char(C#), Int(I#), IO(IO))+import GHC.Word (Word8(W8#))+import System.IO.Unsafe (unsafeDupablePerformIO)++{-# INLINE cmpres #-}+-- | Newer versions of GHC return an Int# instead of a Bool for+-- primitive comparison functions.  The @cmpres@ function converts the+-- result of such a comparison to a @Bool@.+#if __GLASGOW_HASKELL__ >= 707+cmpres :: Int# -> Bool+cmpres 0# = False+cmpres _ = True+#else /* __GLASGOW_HASKELL__ < 707 */+cmpres :: Bool -> Bool+cmpres b = b+#define cmpres(b) b+#endif /* __GLASGOW_HASKELL__ < 707 */++c2b :: Char -> Word8+c2b (C# i) = W8# (int2Word# (ord# i))++c2b# :: Char -> Word#+c2b# (C# i) = int2Word# (ord# i)++inlinePerformIO :: IO a -> a+#if MIN_VERSION_bytestring(0,10,6)+inlinePerformIO = S.accursedUnutterablePerformIO+#else+inlinePerformIO = S.inlinePerformIO+#endif++fastFindIndex :: (Word# -> Bool) -> S.ByteString -> Maybe Int+{-# INLINE fastFindIndex #-}+fastFindIndex test bs =+  inlinePerformIO $ S.unsafeUseAsCStringLen bs $ \(Ptr bsp0, I# bsl0) -> do+    let bse = bsp0 `plusAddr#` bsl0+        check bsp = IO $ \rw -> case readWord8OffAddr# bsp 0# rw of+          (# rw1, w #) -> (# rw1, test w #)+        go bsp | cmpres(bsp `geAddr#` bse) = return Nothing+               | otherwise = do+                 match <- check bsp+                 if match+                   then return $ Just $ I# (bsp `minusAddr#` bsp0)+                   else go (bsp `plusAddr#` 1#)+    go bsp0++fastBreak :: (Word# -> Bool) -> S.ByteString -> (S.ByteString, S.ByteString)+{-# INLINE fastBreak #-}+fastBreak test bs+  | Just n <- fastFindIndex test bs = (S.unsafeTake n bs, S.unsafeDrop n bs)+  | otherwise                       = (bs, S.empty)++quoter :: S.ByteString -> S.ByteString -> (Word# -> Bool)+          -> (Word8 -> Builder) -> S.ByteString -> Builder+{-# INLINE quoter #-}+quoter start end escPred escFn bs0 =+  mconcat [byteStringCopy start, escaped bs0, byteStringCopy end]+  where escaped bs = case fastBreak escPred bs of+          (h, t) | S.null t  -> byteString h+                 | otherwise -> byteString h <>+                                escFn (S.unsafeHead t) <>+                                escaped (S.unsafeTail t)++-- | Quote an identifier using unicode quoting syntax.  This is+-- necessary for identifiers containing a question mark, as otherwise+-- "PostgreSQL.Simple"'s naive formatting code will attempt to match+-- the question mark to a paremeter.+uBuildIdent :: S.ByteString -> Builder+uBuildIdent ident = quoter " U&\"" "\"" isSpecial esc ident+  where isSpecial 34## = True   -- '"'+        isSpecial 63## = True   -- '?'+        isSpecial 92## = True   -- '\\'+        isSpecial _    = False+        esc c = byteStringCopy $ case () of+          _ | c == c2b '"'  -> "\"\""+            | c == c2b '?'  -> "\\003f"+            | c == c2b '\\' -> "\\\\"+            | otherwise     -> error "uquoteIdent"++-- | Build a quoted identifier.  Generally you will want to use+-- 'quoteIdent', and for repeated use it will be faster to use+-- @'byteString' . 'quoteIdent'@, but this internal function is+-- exposed in case it is useful.+buildIdent :: S.ByteString -> Builder+buildIdent ident+  | Just _ <- fastFindIndex isQuestionmark ident = uBuildIdent ident+  | otherwise = quoter "\"" "\"" isDQuote (const $ byteStringCopy "\"\"") ident+  where isQuestionmark 63## = True+        isQuestionmark 0##  = error "quoteIdent: illegal NUL character"+        isQuestionmark _    = False+        isDQuote 34## = True+        isDQuote _    = False++-- | Quote an identifier such as a table or column name using+-- double-quote characters.  Note this has nothing to do with quoting+-- /values/, which must be quoted using single quotes.  (Anyway, all+-- values should be quoted by 'query' or 'fmtSql'.)  This function+-- uses a unicode escape sequence to escape \'?\' characters, which+-- would otherwise be expanded by 'query', 'formatQuery', or 'fmtSql'.+--+-- >>> S8.putStrLn $ quoteIdent "hello \"world\"!"+-- "hello ""world""!"+-- >>> S8.putStrLn $ quoteIdent "hello \"world\"?"+--  U&"hello ""world""\003f"+--+-- Note that this quoting function is correct only if+-- @client_encoding@ is @SQL_ASCII@, @client_coding@ is @UTF8@, or the+-- identifier contains no multi-byte characters.  For other coding+-- schemes, this function may erroneously duplicate bytes that look+-- like quote characters but are actually part of a multi-byte+-- character code.  In such cases, maliciously crafted identifiers+-- will, even after quoting, allow injection of arbitrary SQL commands+-- to the server.+--+-- The upshot is that it is unwise to use this function on identifiers+-- provided by untrustworthy sources.  Note this is true anyway,+-- regardless of @client_encoding@ setting, because certain \"system+-- column\" names (e.g., @oid@, @tableoid@, @xmin@, @cmin@, @xmax@,+-- @cmax@, @ctid@) are likely to produce unexpected results even when+-- properly quoted.+--+-- See 'Id' for a convenient way to include quoted identifiers in+-- parameter lists.+quoteIdent :: S.ByteString -> S.ByteString+quoteIdent = toStrict . toLazyByteString . buildIdent++hexNibblesPtr :: Ptr Word8+{-# NOINLINE hexNibblesPtr #-}+hexNibblesPtr = unsafeDupablePerformIO $ do+  ptr <- mallocBytes 16+  sequence_ $ zipWith (\o v -> pokeByteOff ptr o $ c2b v)+    [0..] (['0'..'9'] ++ ['a'..'f'])+  return ptr++-- | Bad things will happen if the argument is greater than 0xff.+uncheckedWriteNibbles# :: Addr# -> Word# -> State# d -> State# d+{-# INLINE uncheckedWriteNibbles# #-}+uncheckedWriteNibbles# p w rw0 =+  case (# word2Int# (w `uncheckedShiftRL#` 4# )+       , word2Int# (w `and#` 0xf## ) #) of { (# h, l #) ->+  case readWord8OffAddr# nibbles h rw0 of { (# rw1, hascii #) ->+  case writeWord8OffAddr# p 0# hascii rw1 of { rw2 ->+  case readWord8OffAddr# nibbles l rw2 of { (# rw3, lascii #) ->+  writeWord8OffAddr# p 1# lascii rw3 }}}}+  where !(Ptr nibbles) = hexNibblesPtr++hexCharEscBuilder :: Word8 -> Builder+{-# INLINE hexCharEscBuilder #-}+hexCharEscBuilder (W8# w) = fromWrite $ exactWrite 4 $ \(Ptr p) -> IO $ \rw0 ->+  (# uncheckedWriteNibbles# (p `plusAddr#` 2#) w+   (writeWord8OffAddr# p 1# (c2b# 'x')+    (writeWord8OffAddr# p 0# (c2b# '\\') rw0))+  , () #)++buildLiteral :: S.ByteString -> Builder+buildLiteral = quoter " E'" "'" isSpecial esc+  where isSpecial 39## = True   -- '\''+        isSpecial 63## = True   -- '?'+        isSpecial 92## = True   -- '\\'+        isSpecial b    = cmpres(b `geWord#` 128##)+        esc b | b == c2b '\'' = byteStringCopy "''"+              | b == c2b '\\' = byteStringCopy "\\\\"+              | otherwise     = hexCharEscBuilder b+++copyByteToNibbles :: Addr# -> Addr# -> IO ()+{-# INLINE copyByteToNibbles #-}+copyByteToNibbles src dst = IO $ \rw0 ->+  case readWord8OffAddr# src 0# rw0 of+    (# rw1, w #) -> (# uncheckedWriteNibbles# dst w rw1, () #)++buildByteA :: S.ByteString -> Builder+buildByteA bs = equote $+  builder $ \cont (BufferRange (Ptr bb0) (Ptr be0)) ->+    S.unsafeUseAsCStringLen bs $ \(Ptr inptr0, I# inlen0) -> do+    let ine = plusAddr# inptr0 inlen0+        fill oute inp outp+          | cmpres(inp `geAddr#` ine) = cont (BufferRange (Ptr outp) (Ptr oute))+          | cmpres(plusAddr# outp 2# `geAddr#` oute) = return $+              bufferFull (2 * (I# (ine `minusAddr#` inp)) + 1) (Ptr outp) $+              \(BufferRange (Ptr bb) (Ptr be)) -> fill be inp bb+          | otherwise = do copyByteToNibbles inp outp+                           fill oute (inp `plusAddr#` 1#) (outp `plusAddr#` 2#)+    fill be0 inptr0 bb0+  where equote b = mconcat [byteString " E'\\\\x", b, char8 '\'']++++buildAction :: Action -> Builder+buildAction (Plain b)             = b+buildAction (Escape bs)           = buildLiteral bs+buildAction (EscapeByteA bs)      = buildByteA bs+buildAction (EscapeIdentifier bs) = buildIdent bs+buildAction (Many bs)             = mconcat $ map buildAction bs++-- | A lower-level function used by 'buildSql' and 'fmtSql'.  You+-- probably don't need to call it directly.+buildSqlFromActions :: Query -> [Action] -> Builder+buildSqlFromActions (Query template) actions =+  intercatlate (split template) (map buildAction $ actions)+  where intercatlate (t:ts) (p:ps) = t <> p <> intercatlate ts ps+        intercatlate [t] []        = t+        intercatlate _ _           =+          error $ "buildSql: wrong number of parameters for " ++ show template+        split s = case S.break (== c2b '?') s of+          (h,t) | S.null t  -> [byteString h]+                | otherwise -> byteString h : split (S.unsafeTail t)++-- | A builder version of 'fmtSql', possibly useful if you are about+-- to concatenate various individually formatted query fragments and+-- want to save the work of concatenating each individually.+buildSql :: (ToRow p) => Query -> p -> Builder+{-# INLINE buildSql #-}+buildSql q p = buildSqlFromActions q (toRow p)++-- | Take a SQL template containing \'?\' characters and a list of+-- paremeters whose length must match the number of \'?\' characters,+-- and format the result as an escaped 'S.ByteString' that can be used+-- as a query.+--+-- Like 'formatQuery', this function is naive about the placement of+-- \'?\' characters and will expand all of them, even ones within+-- quotes.  To avoid this, you must use 'quoteIdent' on identifiers+-- containing question marks.+--+-- Also like 'formatQuery', \'?\' characters touching other \'?\'+-- characters or quoted strings may do the wrong thing, and end up+-- doubling a quote, so avoid substrings such as @\"??\"@ or+-- @\"?'string'\"@, as these could get expanded to, e.g.,+-- @\"\'param''string'\"@, which is a single string containing an+-- apostrophe, when you probably wanted two strings.+fmtSql :: (ToRow p) => Query -> p -> Query+{-# INLINE fmtSql #-}+fmtSql q p = Query $ toStrict . toLazyByteString $ buildSql q p
+ src/Database/PostgreSQL/Migrate.hs view
@@ -0,0 +1,254 @@+{-# LANGUAGE CPP, OverloadedStrings #-}++-- | Functions for creating and running database migrations. You should+-- probably be using the `pg_migrate` executable to run migrations, however+-- these functions are exposed for developers that want to integrate migrations+-- more tightly into their applications or utilities.++module Database.PostgreSQL.Migrate+  ( initializeDb+  , runMigrationsForDir+  , runRollbackForDir+  , compileMigrationsForDir+  , dumpDb+  , newMigration+  , defaultMigrationsDir+  , getDirectoryMigrations+  , MigrationDetails(..)+  ) where++import Control.Monad+import Data.List+import Data.Time+import Database.PostgreSQL.Simple hiding (connect)+import qualified Data.ByteString.Char8 as S8+import Database.PostgreSQL.Migrations+import Language.Haskell.Exts+  (parseFile, fromParseResult,+   Module(..), ModuleHead(..), ModuleName(..),+   Decl(..), Pat(..), Name(..))+import Language.Haskell.Exts.Pretty (prettyPrint)+import System.Exit+import GHC.IO.Handle+import System.Process+import System.Directory+import System.FilePath+import System.Environment+import System.IO+import System.IO.Temp (withTempDirectory)+#if !MIN_VERSION_time(1,5,0)+import System.Locale+#endif++import Paths_postgresql_orm++-- | The default relative path containing migrations: @\"db\/migrations\"@+defaultMigrationsDir :: FilePath+defaultMigrationsDir = "db" </> "migrations"++-- | Dumps the database schema to the given file handle.+--+-- This is a wrapper around the utility /pg_dump/ that comes with postgresql.+-- Therefore, /pg_dump/ must be installed on the system.+dumpDb :: Handle -> IO ExitCode+dumpDb outputFile = do+  let opts = ["--schema-only", "-O", "-x"]+  e <- getEnvironment+  let args = case lookup "DATABASE_URL" e of+               Just dburl -> dburl:opts+               Nothing -> opts+  (_, out, err, ph) <- runInteractiveProcess "pg_dump" args Nothing Nothing+  exitCode <- waitForProcess ph+  if exitCode /= ExitSuccess then do+    S8.hGetContents err >>= S8.hPut stderr+    else do+      raw <- S8.hGetContents out+      let clean = S8.concat $ intersperse "\n" $+                    filter ((/= "--") . (S8.take 2)) $+                    S8.lines raw+      S8.hPut outputFile clean+  return exitCode++-- | Initializes the database by creating a \"schema-migrations\" table.+-- This table must exist before running any migrations.+initializeDb :: IO ()+initializeDb = do+  conn <- connectEnv+  void $ execute_ conn+    "create table if not exists schema_migrations (version VARCHAR(28))"++-- | Runs all new migrations in a given directory and dumps the+-- resulting schema to a file \"schema.sql\" in the migrations+-- directory.+--+-- Determining which migrations to run is done by querying the database for the+-- largest version in the /schema_migrations/ table, and choosing all+-- migrations in the given directory with higher versions.+runMigrationsForDir :: Handle -- ^ Log output (probably stdout)+                    -> FilePath -- ^ Path to directory containing migrations+                    -> IO ExitCode+runMigrationsForDir logOut dir = do+  conn <- connectEnv+  res <- query_ conn+          "select version from schema_migrations order by version desc limit 1"+  let latestVersion = case res of+                        [] -> ""+                        (Only latest):_ -> latest+  migrations <- getDirectoryMigrations dir >>=+                    return . (dropWhile (isVersion (<= latestVersion)))+  go migrations+  where go [] = withFile (dir </> ".." </> "schema.sql") WriteMode dumpDb+        go (mig@(MigrationDetails _ _ name):fs) = do+              hPutStrLn logOut $ "=== Running Migration " ++ name+              exitCode <- runMigration mig+              if exitCode == ExitSuccess then do+                hPutStrLn logOut "=== Success"+                go fs+                else do+                  hPutStrLn logOut "=== Migration Failed!"+                  return exitCode++-- | Run a migration. The returned exit code denotes the success or failure of+-- the migration.+runMigration :: MigrationDetails -> IO ExitCode+runMigration (MigrationDetails file vers _) = do+  rawSystem "runghc"+    [file, "up", vers, "--with-db-commit"]++runRollbackForDir :: FilePath -> IO ExitCode+runRollbackForDir dir = do+  conn <- connectEnv+  res <- query_ conn+          "select version from schema_migrations order by version desc limit 1"+  case res of+    [] -> do+      putStrLn "=== DB Fully Rolled Back!"+      return ExitSuccess+    (Only latest):_ -> do+      (Just (mig@(MigrationDetails _ _ name))) <-+                  getDirectoryMigrations dir >>=+                    return . (find (isVersion (== latest)))+      putStrLn $ "=== Running Rollback " ++ name+      exitCode <- runRollback mig+      if exitCode == ExitSuccess then do+        putStrLn "=== Success"+        withFile (dir </> ".." </> "schema.sql") WriteMode dumpDb+        else do+          putStrLn "=== Migration Failed!"+          return exitCode++-- | Run a migration. The returned exit code denotes the success or failure of+-- the migration.+runRollback :: MigrationDetails -> IO ExitCode+runRollback (MigrationDetails file vers _) = do+  rawSystem "runghc"+    [file, "down", vers, "--with-db-commit"]++data MigrationDetails = MigrationDetails { migrationPath :: FilePath+                                         , migrationVersion :: String+                                         , migrationName :: String }+                                         deriving (Show)++getDirectoryMigrations :: FilePath -> IO [MigrationDetails]+getDirectoryMigrations dir = do+  files0 <- getDirectoryContents dir+  let files = filter (('.' /=) . head) $ sort files0+  return $ map (splitFileVersionName dir) files++splitFileVersionName :: FilePath -> FilePath -> MigrationDetails+splitFileVersionName dir file =+  let fileName = takeBaseName file+      parts    = foldr (\chr (hd:result) ->+                          if chr == '_' then+                            "":hd:result+                            else ((chr:hd):result))+                       [""] fileName+      vers  = head parts+      name     = concat $ intersperse "_" $ tail parts+  in MigrationDetails (dir </> file) vers name++isVersion :: (String -> Bool) -> MigrationDetails -> Bool+isVersion cond (MigrationDetails _ v _) = cond v++newMigration :: FilePath -> FilePath -> IO ()+newMigration baseName dir = do+  now <- getZonedTime+  let filePath = (formatTime defaultTimeLocale "%Y%m%d%H%M%S" now) +++                 "_" ++ baseName ++ ".hs"+  origFile <- getDataFileName "static/migration.hs"+  copyFile origFile (dir </> filePath)+++compileMigrationsForDir :: FilePath -> FilePath -> IO ExitCode+compileMigrationsForDir dir exe = do+  migrations <- getDirectoryMigrations dir++  -- Make temporary working directory.+  withTempDirectory "." "migration-compile-" $ \tmpdir -> do+--  ($ "migration-compile") $ \tmpdir -> do++    -- Iterate over migrations in input directory, copying migration+    -- file to working directory, modifying as:+    --   - Add "module Migration<datestamp> (up, down) where" line at+    --     beginning of file, after any LANGUAGE options.+    --   - Remove any main function.+    --   - Collect (label, MigrationYYMMDD) pairs.+    moduleNames <- mapM (fixModule tmpdir) migrations++    -- Copy main program text to working directory, including+    -- migration list.+    makeMain tmpdir $ zip moduleNames migrations++    -- Copy compiler utilities.+    utils <- getDataFileName "static/CompilerUtils.hs"+    copyFile utils (tmpdir </> "CompilerUtils.hs")++    -- Compile migrater, writing executable outside temporary+    -- directory.+    cwd <- getCurrentDirectory+    system $ "cd " ++ tmpdir ++ "; ghc -o " ++ (cwd </> exe) ++ " Main.hs"++-- | Turn migration scripts into valid modules.+fixModule :: FilePath -> MigrationDetails -> IO String+fixModule tmpdir (MigrationDetails path ver _) = do+  let modulename = "Migration" ++ ver+  modin <- parseFile path+  let modout = removeMain $ addModuleHeader modulename $ fromParseResult modin+  writeFile (tmpdir </> modulename <.> "hs") $ prettyPrint modout+  return modulename++-- | Add "MigrationYYYYMMDDHHMMSS" module header.+addModuleHeader :: String -> Module l -> Module l+addModuleHeader name (Module sinfo _ pragmas imports decls) =+  Module sinfo (Just header) pragmas imports decls+  where header = ModuleHead sinfo (ModuleName sinfo name) Nothing Nothing+addModuleHeader _ _ = error "Something wrong..."++-- | Remove main function.+removeMain :: Module l -> Module l+removeMain (Module sinfo header pragmas imports decls) =+  Module sinfo header pragmas imports $ filter (not . isMain) decls+  where isMain :: Decl l -> Bool+        isMain (TypeSig _ [Ident _ "main"] _) = True+        isMain (PatBind _ (PVar _ (Ident _ "main")) _ _) = True+        isMain _ = False+removeMain _ = error "Something wrong..."++-- | Write main program.+makeMain :: FilePath -> [(String, MigrationDetails)] -> IO ()+makeMain tmpdir migrations =+  withFile (tmpdir </> "Main.hs") WriteMode $ \h -> do+    hPutStrLn h "module Main where\n"+    hPutStrLn h "import CompilerUtils\n"+    forM_ migrations $ \(modname, _) -> hPutStrLn h $ "import qualified " ++ modname+    hPutStrLn h "\nmigrations :: MigrationMap"+    hPutStrLn h "migrations = fromList"+    let migs = zipWith (++) ("  [ " : repeat "  , ") $ map doone migrations+    hPutStrLn h $ unlines migs+    hPutStrLn h "  ]\n"+    hPutStrLn h "main :: IO ()"+    hPutStrLn h "main = compiledMain migrations"+    where doone (modname, MigrationDetails _ ver name) =+            "(\"" ++ ver ++ "\",\n" +++            "     Migration \"" ++ ver ++ "_" ++ name ++ "\" " +++            modname ++ ".up " ++ modname ++ ".down)"
+ src/Database/PostgreSQL/Migrations.hs view
@@ -0,0 +1,564 @@+{-# LANGUAGE OverloadedStrings #-}++{- |+Functions to help with building database migrations.++Most users will want to create a database migration using @defaultMain@ as+follows,++>+> import Database.PostgreSQL.Migrations+>+> main = defaultMain up down+>+> up = migrate $ do+>       create_table "posts"+>         [ column "title" "VARCHAR(255) NOT NULL"+>         , column "author_id" "integer references authors(id)"]+>+> down = migrate $ drop_table "posts"+>+-}+module Database.PostgreSQL.Migrations (+    -- * Utilities+    defaultMain+  , connectEnv+  , runSqlFile+    -- * DSL+  , Migration, migrate+  , column+    -- ** Adding+  , create_table+  , add_column+  , create_index+  , create_unique_index+    -- ** Removing+  , drop_table+  , drop_column+  , drop_index+    -- ** Modifying+  , rename_table+  , rename_column+  , change_column+  , rename_index+  , rename_sequence+  , rename_constraint+    -- ** Statements+  , create_table_stmt, add_column_stmt, create_index_stmt+  , drop_table_stmt, drop_column_stmt, drop_index_stmt+  , rename_table_stmt, rename_column_stmt, change_column_stmt+  , rename_index_stmt, rename_sequence_stmt, rename_constraint_stmt+  ) where++import Control.Monad+import Control.Monad.Reader+import qualified Data.ByteString as S+import qualified Data.ByteString.Char8 as S8+import Data.Int+import Data.Maybe+import Database.PostgreSQL.Simple hiding (connect)+import Database.PostgreSQL.Simple.Internal (exec)+import Database.PostgreSQL.Simple.Types+import System.Environment+import System.Exit++import Database.PostgreSQL.Escape++-- | Creates a PostgreSQL 'Connection' using the /DATABASE_URL/ environment+-- variable, if it exists. If it does, it should match the format:+--+-- @+--   postgresql:\/\/[[USERNAME\@PASSWORD]HOSTNAME[:PORT]]/[DBNAME]+-- @+--+-- If it is not present, the environment variables /PG_DBNAME/ /PG_HOST/ etc,+-- are used.+connectEnv :: IO Connection+connectEnv = do+  psqlStr <- getEnvironment >>=+             return . (fromMaybe "") . (lookup "DATABASE_URL")+  connectPostgreSQL $ S8.pack psqlStr++--+-- Migration Monad+--++type Migration = ReaderT Connection IO++migrate :: Migration a -> Connection -> IO ()+migrate = (void .) . runReaderT++executeQuery_ :: Query -> Migration Int64+executeQuery_ q = ask >>= \conn -> liftIO $ execute_ conn q++-- | Runs the SQL file at the given path, relative to the current working+-- directory.+runSqlFile :: FilePath -> Migration ()+runSqlFile sqlFile = void $ do+    conn <- ask+    liftIO $ do+      rawSql <- S.readFile sqlFile+      exec conn rawSql++-- | Returns a column defition by quoting the given name+column :: S8.ByteString -- ^ name+       -> S8.ByteString -- ^ type, definition, constraints+       -> S8.ByteString+column name def = S8.concat [quoteIdent name, " ", def]++-- | Creates a table. See 'column' for constructing the column list.+create_table :: S8.ByteString+             -- ^ Table name+             -> [S8.ByteString]+             -- ^ Column definitions+             -> Migration Int64+create_table = (executeQuery_ .) . create_table_stmt++-- | Returns a 'Query' that creates a table, for example:+--+-- @+--   create_table_stmt \"posts\"+--     [ column \"title\" \"VARCHAR(255) NOT NULL\"+--     , column \"body\"  \"text\"]+-- @+create_table_stmt :: S8.ByteString+                  -- ^ Table name+                  -> [S8.ByteString]+                  -- ^ Column definitions+                  -> Query+create_table_stmt tableName colDefs = Query $ S8.concat $+  [ "create table "+  , quoteIdent tableName+  , " ("] ++ (S8.intercalate ", " colDefs):([");"])++-- | Drops a table+drop_table :: S8.ByteString -> Migration Int64+drop_table = executeQuery_ . drop_table_stmt++-- | Returns a 'Query' that drops a table+drop_table_stmt :: S8.ByteString -> Query+drop_table_stmt tableName = Query $ S8.concat+  [ "drop table ", quoteIdent tableName, ";"]++-- | Adds a column to the given table. For example,+--+-- @+--   add_column \"posts\" \"title\" \"VARCHAR(255)\"+-- @+--+-- adds a varchar column called \"title\" to the table \"posts\".+--+add_column :: S8.ByteString+           -- ^ Table name+           -> S8.ByteString+           -- ^ Column name+           -> S8.ByteString+           -- ^ Column definition+           -> Migration Int64+add_column  = ((executeQuery_ .) .) . add_column_stmt++-- | Returns a 'Query' that adds a column to the given table. For example,+--+-- @+--   add_column_stmt \"posts\" \"title\" \"VARCHAR(255)\"+-- @+--+-- Returns the query+--+-- @+--   ALTER TABLE \"posts\" add \"title\" VARCHAR(255);+-- @+add_column_stmt :: S8.ByteString+                -- ^ Table name+                -> S8.ByteString+                -- ^ Column name+                -> S8.ByteString+                -- ^ Column definition+                -> Query+add_column_stmt tableName colName colDef = Query $ S8.concat+  [ "alter table ", quoteIdent tableName, " add ", column colName colDef, ";"]++-- | Drops a column from the given table. For example,+--+-- @+--   drop_column \"posts\" \"title\"+-- @+--+-- drops the column \"title\" from the \"posts\" table.+drop_column :: S8.ByteString+            -- ^ Table name+            -> S8.ByteString+            -- ^ Column name+            -> Migration Int64+drop_column = (executeQuery_ .) . drop_column_stmt++-- | Returns a 'Query' that drops a column from the given table. For example,+--+-- @+--   drop_column_stmt \"posts\" \"title\"+-- @+--+-- Returns the query+--+-- @+--   ALTER TABLE \"posts\" add \"title\";+-- @+drop_column_stmt :: S8.ByteString+                 -- ^ Table name+                 -> S8.ByteString+                 -- ^ Column name+                 -> Query+drop_column_stmt tableName colName = Query $ S8.concat+  ["alter table ", quoteIdent tableName, " drop ", quoteIdent colName, ";"]++-- | Renames the given table. For example,+--+-- @+--   rename_table \"posts\" \"blog_posts\"+-- @+--+-- renames the \"posts\" table to be called \"blog_posts\".+rename_table :: S8.ByteString+             -- ^ Table name+             -> S8.ByteString+             -- ^ New table name+             -> Migration Int64+rename_table = (executeQuery_ .) . rename_table_stmt++-- | Returns a 'Query' that renames the given table. For example,+--+-- @+--   rename_table_stmt \"posts\" \"blog_posts\"+-- @+--+-- Returns the query+--+-- @+--   ALTER TABLE \"posts\" RENAME TO \"blog_posts\";+-- @+rename_table_stmt :: S8.ByteString+                  -- ^ Table name+                  -> S8.ByteString+                  -- ^ New table name+                  -> Query+rename_table_stmt tableName newTableName = Query $ S8.concat+  [ "alter table ", quoteIdent tableName, " rename to"+  , quoteIdent newTableName, ";"]++-- | Renames the given index. For example,+--+-- @+--   rename_index \"posts_pkey\" \"blog_posts_pkey\"+-- @+--+-- renames the \"posts_pkey\" index to be called \"blog_posts_pkey\".+rename_index :: S8.ByteString+             -- ^ Index name+             -> S8.ByteString+             -- ^ New index name+             -> Migration Int64+rename_index = (executeQuery_ .) . rename_index_stmt++-- | Returns a 'Query' that renames the given table. For example,+--+-- @+--   rename_index_stmt \"posts_pkey\" \"blog_posts_pkey\"+-- @+--+-- Returns the query+--+-- @+--   ALTER INDEX \"posts\" RENAME TO \"blog_posts_pkey\";+-- @+rename_index_stmt :: S8.ByteString+                  -- ^ Index name+                  -> S8.ByteString+                  -- ^ New index name+                  -> Query+rename_index_stmt indexName newIndexName = Query $ S8.concat+  [ "alter index ", quoteIdent indexName, " rename to"+  , quoteIdent newIndexName, ";"]++-- | Renames the given sequence. For example,+--+-- @+--   rename_sequence \"posts_id_seq\" \"blog_posts_id_seq\"+-- @+--+-- renames the \"posts_id_seq\" sequence to be called \"blog_posts_id_seq\".+rename_sequence :: S8.ByteString+                -- ^ Sequence name+                -> S8.ByteString+                -- ^ New sequence name+                -> Migration Int64+rename_sequence = (executeQuery_ .) . rename_sequence_stmt++-- | Returns a 'Query' that renames the given sequence. For example,+--+-- @+--   rename_sequence_stmt \"posts_id_seq\" \"blog_posts_id_seq\"+-- @+--+-- Returns the query+--+-- @+--   ALTER SEQUENCE \"posts_id_seq\" RENAME TO \"blog_posts__id_seq\";+-- @+rename_sequence_stmt :: S8.ByteString+                     -- ^ Sequence name+                     -> S8.ByteString+                     -- ^ New sequence name+                     -> Query+rename_sequence_stmt seqName newSeqName = Query $ S8.concat+  [ "alter sequence ", quoteIdent seqName, " rename to"+  , quoteIdent newSeqName, ";"]++-- | Renames the given constraint. For example,+--+-- @+--   rename_constraint \"posts\" \"posts_author_id_fkey\"+--                               \"blog_posts_author_id_fkey\"+-- @+--+-- renames the \"posts_author_id_fkey\" sequence to be called+-- \"blog_posts_author_id_fkey\".+rename_constraint :: S8.ByteString+                  -- ^ Table name+                  -> S8.ByteString+                  -- ^ Constraint name+                  -> S8.ByteString+                  -- ^ New constraint name+                  -> Migration Int64+rename_constraint = ((executeQuery_ .) .) . rename_constraint_stmt++-- | Returns a 'Query' that renames the given constraint. For example,+--+-- @+--   rename_constraint_stmt \"posts\" \"posts_author_id_fkey\"+--                                    \"blog_posts_author_id_fkey\"+-- @+--+-- Returns the query+--+-- @+--   ALTER TABLE \"posts\" RENAME CONSTRAINT \"posts_author_id_fkey\"+--     RENAME TO \"blog_posts_author_id_fkey\";+-- @+rename_constraint_stmt :: S8.ByteString+                       -- ^ Table name+                       -> S8.ByteString+                       -- ^ Constraint name+                       -> S8.ByteString+                       -- ^ New constraint name+                       -> Query+rename_constraint_stmt tbl conName newConName = Query $ S8.concat+  [ "alter table ", quoteIdent tbl, " rename constraint"+  , quoteIdent conName, "to", quoteIdent newConName, ";"]++-- | Renames a column in the given table. For example,+--+-- @+--   rename_column \"posts\" \"title\" \"name\"+-- @+--+-- renames the column \"title\" in the \"posts\" table to \"name\".+rename_column :: S8.ByteString+              -- ^ Table name+              -> S8.ByteString+              -- ^ Old column name+              -> S8.ByteString+              -- ^ New column name+              -> Migration Int64+rename_column = ((executeQuery_ .) .) . rename_column_stmt++-- | Returns a 'Query' that renames a column in the given table. For example,+--+-- @+--   rename_column_stmt \"posts\" \"title\" \"name\"+-- @+--+-- Returns the query+--+-- @+--   ALTER TABLE \"posts\" RENAME \"title\" TO \"name\";+-- @+rename_column_stmt :: S8.ByteString+                   -- ^ Table name+                   -> S8.ByteString+                   -- ^ Old column name+                   -> S8.ByteString+                   -- ^ New column name+                   -> Query+rename_column_stmt tableName colName colNameNew = Query $ S8.concat+  [ "alter table ", quoteIdent tableName, " rename "+  , quoteIdent colName, " to ", quoteIdent colNameNew, ";"]++-- | Alters a column in the given table. For example,+--+-- @+--   change_column \"posts\" \"title\" \"DROP DEFAULT\"+-- @+--+-- drops the default constraint for the \"title\" column in the \"posts\"+-- table.+change_column :: S8.ByteString+              -- ^ Table name+              -> S8.ByteString+              -- ^ Column name+              -> S8.ByteString+              -- ^ Action+              -> Migration Int64+change_column = ((executeQuery_ .) .) . change_column_stmt++-- | Returns a 'Query' that alters a column in the given table. For example,+--+-- @+--   change_column_stmt \"posts\" \"title\" \"DROP DEFAULT\"+-- @+--+-- Returns the query+--+-- @+--   ALTER TABLE \"posts\" ALTER \"title\" DROP DEFAULT;+-- @+change_column_stmt :: S8.ByteString+                   -- ^ Table name+                   -> S8.ByteString+                   -- ^ Column name+                   -> S8.ByteString+                   -- ^ Action+                   -> Query+change_column_stmt tableName colName action = Query $ S8.concat+  [ "alter table ", quoteIdent tableName, " alter "+  , quoteIdent colName, " ", action, ";"]++data CmdArgs = CmdArgs { cmd :: String+                       , cmdVersion :: String+                       , cmdCommit :: Bool }++-- | Creates an index for efficient lookup.+create_index :: S8.ByteString+             -- ^ Index name+             -> S8.ByteString+             -- ^ Table name+             -> [S8.ByteString]+             -- ^ Column names+             -> Migration Int64+create_index = ((executeQuery_ .) .) . (create_index_stmt False)++-- | Creates a unique index for efficient lookup.+create_unique_index :: S8.ByteString+                    -- ^ Index name+                    -> S8.ByteString+                    -- ^ Table name+                    -> [S8.ByteString]+                    -- ^ Column names+                    -> Migration Int64+create_unique_index = ((executeQuery_ .) .) . (create_index_stmt True)++-- | Returns a 'Query' that creates an index for the given columns on the given+-- table. For example,+--+-- @+--   create_index_stmt \"post_owner_index\" \"posts\" \"owner\"+-- @+--+-- Returns the query+--+-- @+--   CREATE INDEX \"post_owner_index\" ON \"posts\" (\"owner\")+-- @+create_index_stmt :: Bool+                  -- ^ Unique index?+                  -> S8.ByteString+                  -- ^ Index name+                  -> S8.ByteString+                  -- ^ Table name+                  -> [S8.ByteString]+                  -- ^ Column names+                  -> Query+create_index_stmt unq indexName tableName colNames = Query $ S8.concat+  [ "create", unique, " index ", quoteIdent indexName, " on "+  , quoteIdent tableName, " (", cols, ")", ";" ]+  where cols = S8.intercalate ", " $ map quoteIdent colNames+        unique = if unq then " unique" else ""++-- | Drops an index.+drop_index :: S8.ByteString+           -- ^ Index name+           -> Migration Int64+drop_index = executeQuery_ . drop_index_stmt++-- | Returns a 'Query' that drops an index.+--+-- @+--   drop_index_stmt \"post_owner_index\"+-- @+--+-- Returns the query+--+-- @+--   DROP INDEX \"post_owner_index\"+-- @+drop_index_stmt :: S8.ByteString+                -- ^ Index name+                -> Query+drop_index_stmt indexName = Query $ S8.concat+  [ "drop index ", quoteIdent indexName, ";" ]++parseCmdArgs :: [String] -> Maybe CmdArgs+parseCmdArgs args = do+  mycmd <- listToMaybe args+  let args0 = tail args+  myversion <- listToMaybe args0+  return $ go (CmdArgs mycmd myversion False) $ tail args0+  where go res [] = res+        go res (arg:as) =+          let newRes = case arg of+                        "--with-db-commit" -> res { cmdCommit = True }+                        _ -> res+          in go newRes as++defaultMain :: (Connection -> IO ()) -- ^ Migration function+            -> (Connection -> IO ()) -- ^ Rollback function+            -> IO ()+defaultMain up down = do+  (Just cmdArgs) <- getArgs >>= return . parseCmdArgs+  case cmd cmdArgs of+    "up" -> do+      conn <- connectEnv+      res <- query_ conn+          "select version from schema_migrations order by version desc limit 1"+      let currentVersion = case res of+                      [] -> ""+                      (Only v):_ -> v+      let version = cmdVersion cmdArgs+      if currentVersion < version then do+          begin conn+          up conn+          void $ execute conn "insert into schema_migrations values(?)"+                              (Only version)+          if cmdCommit cmdArgs then+            commit conn+            else rollback conn+        else exitWith $ ExitFailure 1+    "down" -> do+      conn <- connectEnv+      res <- query_ conn+          "select version from schema_migrations order by version desc limit 1"+      let currentVersion = case res of+                      [] -> ""+                      (Only v):_ -> v+      let version = cmdVersion cmdArgs+      if currentVersion == version then do+          begin conn+          down conn+          void $ execute conn "delete from schema_migrations where version = ?"+              (Only version)+          if cmdCommit cmdArgs then+            commit conn+            else rollback conn+        else+          exitWith $ ExitFailure 1+    _ -> exitWith $ ExitFailure 1+
+ src/Database/PostgreSQL/ORM.hs view
@@ -0,0 +1,29 @@++module Database.PostgreSQL.ORM (+  -- * The Model class and related types+    Model(modelInfo, modelValid), ModelInfo(..)+  , defaultModelInfo, underscoreModelInfo+  , DBKey(..), DBRef, DBRefUnique, mkDBRef, primaryKey+  , (:.), As(..), RowAlias(..), fromAs+  -- ** Single-row operations+  , findRow, findAll, save, trySave, destroy, destroyByRef+  -- * Abstracted select queries+  , DBSelect(..), modelDBSelect, dbSelectParams, dbSelect+  , addWhere_, addWhere, setOrderBy, setLimit, setOffset+  -- * Associations between models+  , Association, assocSelect, assocProject, assocWhere, findAssoc+  -- ** Parent-child associations+  , GDBRefInfo(..), DBRefInfo, defaultDBRefInfo, dbrefAssocs, has, belongsTo+  -- ** Join table associations+  , JoinTable(..), defaultJoinTable, jtAssocs, jtAdd, jtRemove, jtRemoveByRef+  -- ** Chaining associations+  , nestAssoc, chainAssoc+  -- ** Validations+  , ValidationError(..), validate, validateNotEmpty, validationError+  ) where++import Database.PostgreSQL.ORM.Model+import Database.PostgreSQL.ORM.DBSelect+import Database.PostgreSQL.ORM.Association+import Database.PostgreSQL.ORM.Validations+import Database.PostgreSQL.Simple ((:.))
+ src/Database/PostgreSQL/ORM/Association.hs view
@@ -0,0 +1,543 @@+{-# LANGUAGE CPP #-}+{-# LANGUAGE FlexibleContexts #-}+{-# LANGUAGE FlexibleInstances #-}+{-# LANGUAGE MultiParamTypeClasses #-}+{-# LANGUAGE OverloadedStrings #-}+{-# LANGUAGE ScopedTypeVariables #-}+{-# LANGUAGE TypeOperators #-}++module Database.PostgreSQL.ORM.Association (+    Association(..), assocProject, assocWhere, findAssoc+    -- * Associations based on parent-child relationships+  , GDBRefInfo(..), DBRefInfo, defaultDBRefInfo, dbrefAssocs, has, belongsTo+    -- * Join table Associations+  , JoinTable(..), defaultJoinTable, jtAssocs, joinTable+    -- ** Operations on join tables+  , jtAdd, jtRemove, jtRemoveByRef+    -- ** Semi-internal join table functions+  , jtAddStatement, jtRemoveStatement, jtParam+  , jtFlip, jtAssoc+    -- * Nested and chained associations+  , nestAssoc, chainAssoc+  ) where++#if __GLASGOW_HASKELL__ < 710+import Control.Applicative+#endif+import qualified Data.ByteString as S+import qualified Data.ByteString.Char8 as S8+import Data.List+import Data.Monoid+import Database.PostgreSQL.Simple+import Database.PostgreSQL.Simple.ToField+import Database.PostgreSQL.Simple.Types++import Data.GetField+import Database.PostgreSQL.Escape+import Database.PostgreSQL.ORM.DBSelect+import Database.PostgreSQL.ORM.Model+++-- | A data structure representing a relationship between a model @a@+-- and a model @b@.  At a high level, an @Association a b@ tells you+-- how to find rows of type @b@ given rows of type @a@.  More+-- concretely, this boils down to being able to make two types of+-- query.+--+--  * You want to look up a bunch of @(a ':.' b)@s, filtering using+--  predicates on both @a@ and @b@ (e.g., get a list of recent posts+--  and their authors).  For this purpose, you can use 'assocSelect',+--  which allows you to 'addWhere' predicates mentioning columns in+--  both @a@ and @b@.+--+--  * You already have an instance of type @a@, and want to find all+--  the @b@s associated with it.  For that you use either 'assocWhere'+--  or 'findAssoc' (which internally access fields 'assocSelectOnlyB',+--  'assocWhereQuery', and 'assocWhereParam').  This type of query is+--  strictly less general than the first one, but can be formulated in+--  a more efficient way by extracting values directly from a concrete+--  instance of @a@ without needing to touch table @a@ in the+--  database.+--  +-- Note that an @Association@ is asymmetric.  It tells you how to get+-- @b@s from @a@s, but not vice versa.  In practice, there will almost+-- always be an association in the other direction, too.  Functions+-- such as 'dbrefAssocs' and 'jtAssocs' therefore create an+-- @Association@ and its inverse simultaneously, returning them as a+-- pair.+data Association a b = Association {+    assocSelect :: !(DBSelect (a :. b))+    -- ^ General select returning all instances of @a@ and @b@ that+    -- match according to the association.+  , assocSelectOnlyB :: !(DBSelect b)+    -- ^ The right-hand side of the 'assocSelect' query.  This query+    -- makes no mention of type @a@ (but can be combined with the next+    -- two fields to form an optimized query).  You probably never+    -- want to use this directly, and should instead use either+    -- 'findAssoc' or 'assocWhere'.  Also note this is not useful for+    -- selecting all the @b@s in the relation; for that you should use+    -- 'assocProject'.+  , assocWhereQuery :: !Query+    -- ^ A @WHERE@ clause to find all the 'b's associated with a+    -- particular @a@.  This can often be done more efficiently than+    -- through 'assocSelect'.  The clause contains @\'?\'@ characters+    -- which should be filled in by 'assocWhereParam'.+  , assocWhereParam :: !(a -> [Action])+    -- ^ The query parameters for the query returned by+    -- 'assocWhereQuery'.+  }++instance Show (Association a b) where+  show assoc =+    "Association { assocSelect = " ++ show (assocSelect assoc) +++    ", assocSelectOnlyB = " ++ show (assocSelectOnlyB assoc) +++    ", assocWhereQuery = " ++ S8.unpack (fromQuery $ assocWhereQuery assoc) +++    " }"++-- | A projection of 'assocSelect', extracting only the fields of+-- model @b@.  Note that this query touches table @a@ even if it does+-- not return results from @a@.  Hence, you can use 'addWhere' to add+-- predicates on both @a@ and @b@.  (Note the contrast to+-- 'assocSelectOnlyB', which does not touch table @a@ at all, and+-- hence in the case of an @INNER JOIN@ might return rows of @b@ that+-- should not be part of the association.  'assocSelectOnlyB' is+-- intended for use only in conjunction with 'assocWhereQuery'.)+assocProject :: (Model b) => Association a b -> DBSelect b+assocProject = dbProject . assocSelect++-- | Returns a 'DBSelect' for all @b@s associated with a particular+-- @a@.+assocWhere :: (Model b) => Association a b -> a -> DBSelect b+assocWhere ab a = addWhere (assocWhereQuery ab) (assocWhereParam ab a)+                  (assocSelectOnlyB ab)++-- | Follow an association to return all of the @b@s associated+-- with a particular @a@.  The behavior is similar to:+--+-- > findAssoc' ab c a = dbSelect c $ assocWhere ab a+--+-- But if the first argument is a static association, this function+-- may be marginally faster because it pre-renders most of the query.+findAssoc :: (Model b) => Association a b -> Connection -> a -> IO [b]+{-# INLINE findAssoc #-}+findAssoc assoc = \c a ->+  map lookupRow <$> query c q (assocWhereParam assoc a)+  where {-# NOINLINE q #-}+        q = renderDBSelect $+            addWhere_ (assocWhereQuery assoc) $ assocSelectOnlyB assoc++-- | Combine two associations into one.+nestAssoc :: (Model a, Model b) =>+             Association a b -> Association b c -> Association a (b :. c)+nestAssoc ab bc = ab { assocSelect = dbNest (assocSelect ab) (assocSelect bc)+                     , assocSelectOnlyB = assocSelect bc }++-- | Combine two associations into one, and project away the middle+-- type.  (The middle type can still be mentioned in @WHERE@ clauses.)+--+-- An example:+--+-- > data Author = Author {+-- >     authorId :: DBKey+-- >   } deriving (Show, Generic)+-- > instance Model Author where modelInfo = underscoreModelInfo "author"+-- > +-- > data Post = Post {+-- >     postId :: DBKey+-- >   , postAuthorId :: DBRef Author+-- >   } deriving (Show, Generic)+-- > instance Model Post where modelInfo = underscoreModelInfo "post"+-- > +-- > data Comment = Comment {+-- >     commentId :: DBKey+-- >   , commentPostId :: DBRef Post+-- >   } deriving (Show, Generic)+-- > instance Model Comment where modelInfo = underscoreModelInfo "comment"+-- > +-- > author_posts :: Association Author Post+-- > post_author :: Association Post Author+-- > (post_author, author_posts) = dbrefAssocs defaultDBRefInfo+-- > +-- > -- Could equally well use dbrefAssocs as above+-- > post_comments :: Association Post Comment+-- > post_comments = has+-- >+-- > comment_post :: Association Comment Post+-- > comment_post = belongsTo+-- > +-- > comment_author :: Association Comment Author+-- > comment_author = chainAssoc comment_post post_author+-- > +-- > author_comments :: Association Author Comment+-- > author_comments =  chainAssoc author_posts post_comments+chainAssoc :: (Model a, Model b, Model c) =>+              Association a b -> Association b c -> Association a c+chainAssoc ab bc = ab { assocSelect = dbChain (assocSelect ab) (assocSelect bc)+                      , assocSelectOnlyB = dbProject $ assocSelect bc }+++-- | A common type of association is when one model contains a 'DBRef'+-- or 'DBRefUnique' pointing to another model.  In this case, the+-- model containing the 'DBRef' is known as the /child/, and the+-- referenced model is known as the /parent/.+--+-- Two pieces of information are required to describe a parent-child+-- relationship:  First, the field selector that extracts the Haskell+-- 'DBRef' from the haskell type @child@, and second the name of the+-- database column that stores this 'DBRef' field.+--+-- For example, consider the following:+--+-- > data Author = Author {+-- >     authorId :: DBKey+-- >   } deriving (Show, Generic)+-- > instance Model Author+-- > +-- > data Post = Post {+-- >     postId :: DBKey+-- >   , postAuthorId :: DBRef Author+-- >   } deriving (Show, Generic)+-- > instance Model Post+-- >+-- > post_author_refinfo :: DBRefInfo Post Author+-- > post_author_refinfo = DBRefInfo {+-- >     dbrefSelector = postAuthorId+-- >   , dbrefQColumn = "\"post\".\"postAuthorId\""+-- >   }+--+-- Note that the parent-child relationship described by a @GDBRefInfo@+-- is asymmetric, but bidirectional.  When a @'DBRefInfo' child+-- parent@ exists, the schema should generally /not/ permit the+-- existence of a valid @'DBRefInfo' parent child@ structure.+-- However, the 'dbrefAssocs' function generates 'Association's in+-- both directions from a single 'DBRefInfo'.+--+-- Constructing such parent-child 'Association's requires knowing how+-- to extract primary keys from the @parent@ type as well as the name+-- of the column storing primary keys in @parent@.  Fortunately, this+-- information is already available from the 'Model' class, and thus+-- does not need to be in the @GDBRefInfo@.  (Most functions on+-- @GDBRefInfo@s require @parent@ and @child@ to be instances of+-- 'Model'.)+--+-- When your 'Model's are instances of 'Generic' (which will usually+-- be the case), a 'DBRefInfo' structure can be computed automatically+-- by 'defaultDBRefInfo'.  This is the recommended way to produce a+-- @GDBRefInfo@.  (Alternatively, see 'has' and 'belongsTo' to make+-- use of an entirely implicit @DBRefInfo@.)+data GDBRefInfo reftype child parent = DBRefInfo {+    dbrefSelector :: !(child -> GDBRef reftype parent)+    -- ^ Field selector returning a reference.+  , dbrefQColumn :: !S.ByteString+    -- ^ Literal SQL for the database column storing the reference.+    -- This should be double-quoted and table-qualified, in case the+    -- column name is a reserved keyword, contains capital letters, or+    -- conflicts with the name of a column in the joined table.  An+    -- example would be:+    --+    -- > dbrefQColumn = "\"table_name\".\"column_name\""+  }++instance Show (GDBRefInfo rt c p) where+  show ri = "DBRefInfo ? " ++ show (dbrefQColumn ri)++-- | @DBRefInfo@ is a type alias for the common case that the+-- reference in a 'GDBRefInfo' is a 'DBRef' (as opposed to a+-- 'DBRefUnique').  The functions in this library do not care what+-- type of reference is used.  The type is generalized to 'GDBRefInfo'+-- just to make it easier to assign a selector to 'dbrefSelector' when+-- the selector returns a 'DBRefUnique'.  Note, however, that+-- 'defaultDBRefInfo' returns a 'DBRefInfo' regardless of the flavor+-- of reference actually encountered.+type DBRefInfo = GDBRefInfo NormalRef++data ExtractRef a = ExtractRef deriving (Show)+instance Extractor ExtractRef (GDBRef rt a) (DBRef a) THasOne where+  extract _ (DBRef k) = THasOne $ DBRef k+instance Extractor ExtractRef (GDBRef rt a) (DBRef (As alias a)) THasOne where+  extract _ (DBRef k) = THasOne $ DBRef k+instance Extractor ExtractRef (Maybe (GDBRef rt a)) (DBRef a) THasOne where+  extract _ (Just (DBRef k)) = THasOne $ DBRef k+  extract _ _                = error "Maybe DBRef is Nothing"+instance Extractor ExtractRef (Maybe (GDBRef rt a)) (DBRef (As alias a))+         THasOne where+  extract _ (Just (DBRef k)) = THasOne $ DBRef k+  extract _ _                = error "Maybe DBRef is Nothing"++-- | Creates a 'DBRefInfo' from a model @child@ that references+-- @parent@.  For this to work, the @child@ type must be an instance+-- of 'Generic' and must contain exactly one field of the any of the+-- following types:+--+--   1. @'GDBRef' rt parent@, which matches both @'DBRef' parent@ and+--   @'DBRefUnique' parent@.+--+--   2. @Maybe ('GDBRef' rt parent)@, for cases where the reference+--   might be @NULL@.  Note, however, that an exception will be thrown+--   if you call 'findAssoc' on a child whose reference is 'Nothing'.+--+-- A special case arises when a Model contains a 'DBRef' to itself.+-- If you just wish to find parents and children given an existing+-- structure (i.e., 'findAssoc'), it is okay to declare an+-- @'Association' MyType MyType@.  However, in this case attempts to+-- use 'assocSelect' will then fail.  To work around this problem, the+-- parent must use a row alias.+--+-- Note that currently /aliasing the child will not work/, since the+-- 'As' data structure will not contain a 'DBRef' field, only the+-- contents of the 'As' data structure.  An example of doing this+-- correctly (using 'has' and 'belongsTo', both of which wrap+-- @defaultDBRefInfo@):+--+-- > data Bar = Bar {+-- >     barId :: !DBKey+-- >   , barName :: !String+-- >   , barParent :: !(Maybe (DBRef Bar))+-- >   } deriving (Show, Generic)+-- > instance Model Bar where modelInfo = underscoreModelInfo "bar"+-- > +-- > data ParentBar = ParentBar+-- > instance RowAlias ParentBar where rowAliasName _ = "parent_bar"+-- > +-- > toParent :: Association Bar (As ParentBar Bar)+-- > toParent = belongsTo+-- > +-- > toChild :: Association (As ParentBar Bar) Bar+-- > toChild = has+defaultDBRefInfo :: forall child parent.+                    (Model child, Model parent+                    , GetField ExtractRef child (DBRef parent)) =>+                    DBRefInfo child parent+defaultDBRefInfo = ri+  where extractor = (const ExtractRef :: g p -> ExtractRef (DBRef p)) ri+        child = undefined :: child+        childids = modelIdentifiers :: ModelIdentifiers child+        ri = DBRefInfo {+            dbrefSelector = getFieldVal extractor+          , dbrefQColumn = modelQColumns childids !! getFieldPos extractor child+          }++-- | Generate both the child-parent and parent-child 'Association's+-- implied by a 'GDBRefInfo'.+dbrefAssocs :: forall child parent rt.+               (Model child, Model parent) =>+               GDBRefInfo rt child parent+               -> (Association child parent, Association parent child)+dbrefAssocs ri = (c_p, p_c)+  where idp = modelIdentifiers :: ModelIdentifiers parent+        on = Query $ "ON " <> modelQPrimaryColumn idp+             <> " = " <> dbrefQColumn ri+        c_p = Association {+            assocSelect = dbJoinModels "JOIN" on+          , assocSelectOnlyB = modelDBSelect+          , assocWhereQuery = Query $ modelQPrimaryColumn idp <> " = ?"+          , assocWhereParam = \child -> [toField $ dbrefSelector ri child]+          }+        p_c = Association {+            assocSelect = dbJoinModels "JOIN" on+          , assocSelectOnlyB = modelDBSelect+          , assocWhereQuery = Query $ dbrefQColumn ri <> " = ?"+          , assocWhereParam = \parent -> [toField $ primaryKey parent]+          }+++-- | Short for+--+-- > snd $ dbrefAssocs defaultDBRefInfo+--+-- Note the inverse 'Association' is given by 'belongsTo'.  For+-- example, given the @Author@ and @Post@ models described in the+-- documentation for 'GDBRefInfo', in which each @Post@ references an+-- @Author@, you might say:+--+-- > author_post :: Association Author Post+-- > author_post = has+-- >+-- > post_author :: Association Post Author+-- > post_author = belongsTo+has :: (Model child, Model parent, GetField ExtractRef child (DBRef parent)) =>+       Association parent child+has = snd $ dbrefAssocs defaultDBRefInfo++-- | The inverse of 'has'.  Short for+--+-- > fst $ dbrefAssocs defaultDBRefInfo+--+-- See an example at 'has'.+belongsTo :: (Model child, Model parent+             , GetField ExtractRef child (DBRef parent)) =>+             Association child parent+belongsTo = fst $ dbrefAssocs defaultDBRefInfo++-- | A data structure representing a dedicated join table in the+-- database.  A join table differs from a model in that rows do not+-- have primary keys.  Hence, model operations do not apply.+-- Nonetheless a join table conveys information about a relationship+-- between models.+--+-- Note that all names in a @JoinTable@ should be unquoted.+data JoinTable a b = JoinTable {+    jtTable :: !S.ByteString+    -- ^ Name of the join table in the database.  (Not quoted.)+  , jtColumnA :: !S.ByteString+    -- ^ Name of the column in table 'jtTable' that contains a 'DBRef'+    -- to model @a@.  (Not quoted or table-qualified.)+  , jtColumnB :: !S.ByteString+    -- ^ Like 'jtColumnA' for model @b@.+  } deriving (Show)++-- | The default join table has the following fields:+--+-- * 'jtName' is the name of the two models (in alphabetical order),+-- separated by an @\'_\'@ character.+--+-- * 'jtColumnA' is the name of model @a@, an @\'_\'@ character, and+-- the name of the primary key column in table @a@.+--+-- * 'jtColumnB' is the name of model @b@, an @\'_\'@ character, and+-- the name of the primary key column in table @b@.+--+-- Note that 'defaultJoinTable' cannot create a default join table for+-- joining a model to itself, as following these rules the two columns+-- would have the same name.  If you wish to join a table to itself,+-- you have two options:  First, you can define the join table and+-- assign the column names manually.  This will permit you to call+-- 'findAssoc', but you still will not be able to use 'assocSelect'+-- for more complex queries, since SQL does not permit joins between+-- two tables with the same name.  The second option is to give one of+-- the sides of the join table a row alias with 'As'.  For example:+--+-- > data ParentBar = ParentBar+-- > instance RowAlias ParentBar where rowAliasName _ = "parent_bar"+-- > +-- > selfJoinTable :: JoinTable Bar (As ParentBar Bar)+-- > selfJoinTable = defaultJoinTable+-- > +-- > selfJoin :: Association Bar (As ParentBar Bar)+-- > otherSelfJoin :: Association (As ParentBar Bar) Bar+-- > (selfJoin, otherSelfJoin) = jtAssocs selfJoinTable+defaultJoinTable :: forall a b. (Model a, Model b) => JoinTable a b+defaultJoinTable+  | colA == colB = error "defaultJoinTable has default for self joins"+  | otherwise = jti+  where a = modelInfo :: ModelInfo a+        b = modelInfo :: ModelInfo b+        colA = S.intercalate "_"+               [modelTable a, modelColumns a !! modelPrimaryColumn a]+        colB = S.intercalate "_"+               [modelTable b, modelColumns b !! modelPrimaryColumn b]+        jti = JoinTable {+            jtTable = S.intercalate "_" $ sort [modelTable a, modelTable b]+          , jtColumnA = colA+          , jtColumnB = colB+          }++jtQTable :: JoinTable a b -> S.ByteString+jtQTable = quoteIdent . jtTable++jtQColumnA :: JoinTable a b -> S.ByteString+jtQColumnA jt = S.concat [ jtQTable jt, ".", quoteIdent $ jtColumnA jt]++jtQColumnB :: JoinTable a b -> S.ByteString+jtQColumnB jt = S.concat [ jtQTable jt, ".", quoteIdent $ jtColumnB jt]++-- | Flip a join table.  This doesn't change the name of the table+-- (since the same join table is used in both directions, and the+-- default join table name glues together the two model names in+-- alphabetical order anyway).+jtFlip :: JoinTable a b -> JoinTable b a+jtFlip jt = jt { jtColumnA = jtColumnB jt , jtColumnB = jtColumnA jt }++-- | A SQL statement suitable for adding a pair to a join table.  Note+-- that the statement takes two parameters (i.e., contains two @\'?\'@+-- characters) corresponding to the primary keys of the two models+-- being associated.  These parameters can be supplied by 'jtParam'.+jtAddStatement :: JoinTable a b -> Query+jtAddStatement jt = Query $ S.concat [+    "INSERT INTO ", jtQTable jt, " ("+  , quoteIdent $ jtColumnA jt, ", ", quoteIdent $ jtColumnB jt+  , ") VALUES (?, ?) EXCEPT SELECT "+  , jtQColumnA jt, ", ", jtQColumnB jt, " FROM ", quoteIdent $ jtTable jt+  ]++-- | Add an association between two models to a join table.  Returns+-- 'True' if the association was not already there.+jtAdd :: (Model a, Model b) => JoinTable a b -> Connection -> a -> b -> IO Bool+{-# INLINE jtAdd #-}+jtAdd jt = \c a b -> (/= 0) <$> execute c q (jtParam jt a b)+  where {-# NOINLINE q #-}+        q = jtAddStatement jt++-- | A SQL statement for removing a pair from a join table.  Like+-- 'jtAddStatement', the query is parameterized by two primary keys.+jtRemoveStatement :: JoinTable a b -> Query+jtRemoveStatement jt = Query $ S.concat [+    "DELETE FROM ", quoteIdent $ jtTable jt, " WHERE "+  , jtQColumnA jt, " = ? AND ", jtQColumnB jt, " = ?"+  ]++-- | Remove an association from a join table.  Returns 'True' if the+-- association was previously there.+jtRemove :: (Model a, Model b) =>+            JoinTable a b -> Connection -> a -> b -> IO Bool+{-# INLINE jtRemove #-}+jtRemove jt = \c a b -> (/= 0) <$> execute c q (jtParam jt a b)+  where {-# NOINLINE q #-}+        q = jtRemoveStatement jt++-- | Remove an assocation from a join table when you don't have the+-- target instances of the two models handy, but do have references.+jtRemoveByRef :: (Model a, Model b) => JoinTable a b+                 -> Connection -> GDBRef rt a -> GDBRef rt b -> IO Bool+{-# INLINE jtRemoveByRef #-}+jtRemoveByRef jt = \c a b -> (/= 0) <$> execute c q (a, b)+  where {-# NOINLINE q #-}+        q = jtRemoveStatement jt++-- | Generate parameters for 'jtAddStatement' and 'jtRemoveStatement'.+-- The returned list is suitable for use as a 'ToRow' instance.  For+-- example:+--+-- > execute conn (jtAddStatement my_join_table) (jtParam a b)+jtParam :: (Model a, Model b) => JoinTable a b -> a -> b -> [Action]+jtParam _ a b = [toField $ primaryKey a, toField $ primaryKey b]++-- | Generate a one-way association from a 'JoinTable'.  Use+-- 'jtAssocs' instead.+jtAssoc :: forall a b. (Model a, Model b) => JoinTable a b -> Association a b+jtAssoc jt = Association {+    assocSelect = dbJoin modelDBSelect "JOIN" onlyB $ Query $ S.concat [+       "ON ", priA, " = ", jtQColumnA jt]+  , assocSelectOnlyB = onlyB+  , assocWhereQuery = Query $ jtQColumnA jt <> " = ?"+  , assocWhereParam = \a -> [toField $ primaryKey a]+  }+  where priA = modelQPrimaryColumn (modelIdentifiers :: ModelIdentifiers a)+        priB = modelQPrimaryColumn (modelIdentifiers :: ModelIdentifiers b)+        selB = modelDBSelect :: DBSelect b+        fromB = FromJoin+                (FromModel (Query $ jtQTable jt) (jtQTable jt))+                "JOIN" (selFrom selB)+                (Query $ S.concat ["ON ", jtQColumnB jt, " = ", priB])+                (jtQTable jt <> "->B")+        onlyB = selB { selFrom = fromB }++-- | Generate the two associations implied by a 'JoinTable'.+jtAssocs :: (Model a, Model b) =>+            JoinTable a b -> (Association a b, Association b a)+jtAssocs jt = (jtAssoc jt, jtAssoc $ jtFlip jt)++-- | Generate a one-way association based on the default join table+-- naming scheme described at 'defaultJoinTable'.  Defined as:+--+-- > joinTable = jtAssoc defaultJoinTable+--+-- For example:+--+-- > aToB :: Association A B+-- > aToB = joinTable+-- >+-- > bToA :: Association B A+-- > bToA = joinTable+joinTable :: (Model a, Model b) => Association a b+joinTable = jtAssoc defaultJoinTable
+ src/Database/PostgreSQL/ORM/CreateTable.hs view
@@ -0,0 +1,104 @@+{-# LANGUAGE FlexibleContexts #-}+{-# LANGUAGE ScopedTypeVariables #-}+{-# LANGUAGE TypeOperators #-}+{-# LANGUAGE OverloadedStrings #-}++-- | Functions for creating a table from a model.  These are mostly+-- useful in development, for very rigid applications, or to compare+-- what would be created against what is actually in the database.  In+-- practice, production settings should create and update tables using+-- migrations.+--+-- Note that often it is more interesting to see what would be created+-- than to create an actual table.  For that reason, functions+-- creating the statements are exposed.+module Database.PostgreSQL.ORM.CreateTable (+  modelCreateStatement, modelCreate, GDefTypes(..)+  , jtCreateStatement, jtCreate+  ) where++import qualified Data.ByteString as S+import qualified Data.ByteString.Char8 as S8+import Data.Int+import Data.List+import Data.Monoid+import Database.PostgreSQL.Simple+import Database.PostgreSQL.Simple.Types+import GHC.Generics++import Database.PostgreSQL.ORM.Model+import Database.PostgreSQL.ORM.Association+import Database.PostgreSQL.ORM.SqlType++-- | This is a helper class used to extract the row types.  You don't+-- need to use this class.  If you are creating custom types, just+-- declare an instance of 'SqlType'.+class GDefTypes f where+  gDefTypes :: f p -> [S.ByteString]+instance (SqlType c) => GDefTypes (K1 i c) where+  gDefTypes ~(K1 c) = [sqlType c]+instance (GDefTypes a, GDefTypes b) => GDefTypes (a :*: b) where+  gDefTypes ~(a :*: b) = gDefTypes a ++ gDefTypes b+instance (GDefTypes f) => GDefTypes (M1 i c f) where+  gDefTypes ~(M1 fp) = gDefTypes fp++customModelCreateStatement :: forall a.+  (Model a, Generic a, GDefTypes (Rep a)) =>+  [(S.ByteString, S.ByteString)]+  -- ^ A list of @(@/field/@,@/type/@)@ pairs to overwrite the default+  -- SQL types of fields.+  -> [S.ByteString]+  -- ^ A list of extra table constraints.+  -> a+  -- ^ A non-strict argument to specify which model's table you want+  -- to create.  @(undefined :: YourModel)@ should be fine.+  -> Query+customModelCreateStatement except constraints a+  | not (null extraneous) =+    error $ "customCreateTableStatement: no such columns: " ++ show extraneous+  | otherwise = Query $ S.concat [+  "CREATE TABLE ", quoteIdent $ modelTable info, " ("+  , S.intercalate ", " (go types names)+  , S.concat $ concatMap (\c -> [", ", c]) constraints, ")"+  ]+  where extraneous = fst (unzip except) \\ names+        types = gDefTypes $ from a+        info = modelInfo :: ModelInfo a+        names = modelColumns info+        go (t:ts) (n:ns)+          | Just t' <- lookup n except = quoteIdent n <> " " <> t' : go ts ns+          | otherwise = quoteIdent n <> " " <> t : go ts ns+        go [] [] = []+        go _ _ = error $ "createTable: " ++ S8.unpack (modelTable info) +++                 " has incorrect number of columns"++-- | Statement for creating the table corresponding to a model.  Not+-- strict in its argument.+modelCreateStatement :: forall a. (Model a, Generic a, GDefTypes (Rep a))+                     => a -> Query+modelCreateStatement a = customModelCreateStatement except constraints a+  where ModelCreateInfo except constraint = modelCreateInfo :: ModelCreateInfo a+        constraints = if S.null constraint then [] else [constraint]++-- | Create a the database table for a model.+modelCreate :: (Model a, Generic a, GDefTypes (Rep a)) =>+               Connection -> a -> IO Int64+modelCreate c a = execute_ c (modelCreateStatement a)++-- | Create the database table corresponding to a 'JoinTable'.+jtCreateStatement :: (Model a, Model b) => JoinTable a b -> Query+jtCreateStatement jt = Query $ S.concat [+    "CREATE TABLE ", quoteIdent $ jtTable jt, " ("+    , S.intercalate ", " $ sort [typa, typb]+    , ", UNIQUE (", S.intercalate ", " $ sort [ida, idb], "))"+  ]+  where ida = quoteIdent $ jtColumnA jt+        idb = quoteIdent $ jtColumnB jt+        refa = (undefined :: JoinTable a b -> DBRef a) jt+        refb = (undefined :: JoinTable a b -> DBRef b) jt+        typa = ida <> " " <> sqlBaseType refa <> " ON DELETE CASCADE NOT NULL"+        typb = idb <> " " <> sqlBaseType refb <> " ON DELETE CASCADE NOT NULL"++-- | Create a join table in the database.+jtCreate :: (Model a, Model b) => Connection -> JoinTable a b -> IO Int64+jtCreate c jt = execute_ c (jtCreateStatement jt)
+ src/Database/PostgreSQL/ORM/DBSelect.hs view
@@ -0,0 +1,473 @@+{-# LANGUAGE Trustworthy #-}+{-# LANGUAGE CPP #-}+{-# LANGUAGE DeriveGeneric #-}+{-# LANGUAGE FlexibleInstances #-}+{-# LANGUAGE OverloadedStrings #-}+{-# LANGUAGE ScopedTypeVariables #-}+{-# LANGUAGE TypeOperators #-}+{-# LANGUAGE RecordWildCards #-}++module Database.PostgreSQL.ORM.DBSelect (+    -- * The DBSelect structure+    DBSelect(..), FromClause(..)+    -- * Executing DBSelects+  , dbSelectParams, dbSelect+  , Cursor(..), curSelect, curNext+  , dbFold, dbFoldM, dbFoldM_+  , dbCollect+  , renderDBSelect, buildDBSelect+    -- * Creating DBSelects+  , emptyDBSelect, expressionDBSelect+  , modelDBSelect+  , dbJoin, dbJoinModels+  , dbProject, dbProject'+  , dbNest, dbChain+    -- * Altering DBSelects+  , addWhere_, addWhere, setOrderBy, setLimit, setOffset, addExpression+  ) where++import Control.Monad.IO.Class+import Blaze.ByteString.Builder+import Blaze.ByteString.Builder.Char.Utf8 (fromChar)+import qualified Data.ByteString as S+import qualified Data.ByteString.Char8 as S8+#if __GLASGOW_HASKELL__ < 710+import Data.Functor+#endif+import Data.Monoid+import Data.String+import Data.IORef+import Database.PostgreSQL.Simple+import Database.PostgreSQL.Simple.Internal+import Database.PostgreSQL.Simple.Types+import GHC.Generics++import Database.PostgreSQL.Escape+import Database.PostgreSQL.ORM.Model++-- | As it's name would suggest, a @FromClause@ is the part of a query+-- between the @FROM@ keyword and the @WHERE@ keyword.  It can consist+-- of simple table names, @JOIN@ operations, and parenthesized+-- subqueries.+--+-- From clauses are represented in a more structured way than the+-- other fields so as to allow the possibility of collapsing join+-- relations.  For instance, given a @'DBSelect' (A :. B)@ and a+-- @'DBSelect' (B :. C)@, it is desirable to be able to generate a+-- @'DBSelect' (A :. B :. C)@ in which each pair of terms involving+-- @B@ in the three-way relation is constrained according to the+-- original two queries.  This functionality is provided by 'dbNest'+-- and 'dbChain', but it requires the ability to locate and replace+-- the instance of type @B@ in one 'DBSelect' with the @FromClause@ of+-- the other 'DBSelect'.+--+-- The 'fcCanonical' field is a canonical name of each type, which by+-- convention is the quoted and fully-qualified table name.  Comparing+-- 'fcCanonical' is somewhat of a hack, and happens entirely at+-- runtime.  It would be nicer to do this at compile time, but doing+-- so would require language extensions such as @GADTs@ of+-- @FunctionalDependencies@.+data FromClause = FromModel {+    fcVerbatim :: !Query -- ^ Verbatim SQL for a table, table @AS@+                         -- alias, or parenthesized subquery.+  , fcCanonical :: !S.ByteString+    -- ^ Canonical name of the table or join relation represented by+    -- this term.  For @JOIN@ terms, this is always the @CROSS JOIN@+    -- of the canonical names of 'fcLeft' and 'fcRight'.  This means+    -- one can locate a join given only it's type (e.g., the canonical+    -- name for @A :. B@ is always @\"a CROSS JOIN b\"@), but it does+    -- mean you have to be careful not accidentally to merge two+    -- different joins on the same types.  For this reason it may be+    -- safest always to have type @b@ be a single table in 'dbNest'+    -- and 'dbChain'.+  }+  | FromJoin {+    fcLeft :: !FromClause+  , fcJoinOp :: !Query -- ^ Usually @\"JOIN\"@+  , fcRight :: !FromClause+  , fcOnClause :: !Query -- ^ @ON@ or @USING@ clause (or empty)+  , fcCanonical :: !S.ByteString+  }+  deriving Show++nullFrom :: FromClause -> Bool+nullFrom (FromModel q _) | qNull q = True+nullFrom _                         = False++-- | A deconstructed SQL select statement that allows easier+-- manipulation of individual terms.  Several functions are provided+-- to combine the 'selFields', 'selFrom', and 'selWhere' clauses of+-- muliple @DBSelect@ structures.  Other clauses may be discarded when+-- combining queries with join operations.  Hence it is advisable to+-- set the other clauses at the end (or, if you set these fields, to+-- collapse your 'DBSelect' structure into a subquery using+-- `dbProject'`).+data DBSelect a = DBSelect {+    selWith :: !Query+  , selSelectKeyword :: !Query+    -- ^ By default @\"SELECT\"@, but might usefully be set to+    -- something else such as @\"SELECT DISTINCT\"@ in some+    -- situations.+  , selFields :: Query+  , selFrom :: !FromClause+  , selWhereKeyword :: !Query+    -- ^ Empty by default, but set to @\"WHERE\"@ if any @WHERE@+    -- clauses are added to the 'selWhere' field.+  , selWhere :: !Query+  , selGroupBy :: !Query+  , selHaving :: !Query+    -- below here, should appear outside any union+  , selOrderBy :: !Query+  , selLimit :: !Query+  , selOffset :: !Query+  } deriving (Generic)++instance Show (DBSelect a) where+  show = S8.unpack . fromQuery . renderDBSelect++space :: Builder+space = fromChar ' '++qNull :: Query -> Bool+qNull = S.null . fromQuery++qBuilder :: Query -> Builder+qBuilder = fromByteString . fromQuery++toQuery :: Builder -> Query+toQuery = Query . toByteString++buildFromClause :: FromClause -> Builder+buildFromClause (FromModel q _) | qNull q = mempty+buildFromClause cl0 = fromByteString " FROM " <> go cl0+  where go (FromModel q _) = qBuilder q+        go (FromJoin left joinkw right onClause _) = mconcat [+            fromChar '(', go left, space, qBuilder joinkw, space, go right+          , if qNull onClause then mempty else space <> qBuilder onClause+          , fromChar ')' ]++class GDBS f where+  gdbsDefault :: f p+  gdbsQuery :: f p -> Builder+instance GDBS (K1 i Query) where+  gdbsDefault = K1 (Query S.empty)+  gdbsQuery (K1 q) | qNull q = mempty+                   | otherwise = space <> qBuilder q+instance GDBS (K1 i FromClause) where+  gdbsDefault = K1 (FromModel "" "")+  gdbsQuery (K1 fc) = buildFromClause fc+instance (GDBS a, GDBS b) => GDBS (a :*: b) where+  gdbsDefault = gdbsDefault :*: gdbsDefault+  gdbsQuery (a :*: b) = gdbsQuery a <> gdbsQuery b+instance (GDBS f) => GDBS (M1 i c f) where+  gdbsDefault = M1 gdbsDefault+  gdbsQuery = gdbsQuery . unM1++-- | A 'DBSelect' structure with keyword @\"SELECT\"@ and everything+-- else empty.+emptyDBSelect :: DBSelect a+emptyDBSelect = (to gdbsDefault) { selSelectKeyword = fromString "SELECT" }++-- | A 'DBSelect' for one or more comma-separated expressions, rather+-- than for a table.  For example, to issue the query @\"SELECT+-- lastval()\"@:+--+-- > lastval :: DBSelect (Only DBKeyType)+-- > lastval = expressionDBSelect "lastval ()"+-- >+-- >   ...+-- >   [just_inserted_id] <- dbSelect conn lastval+--+-- On the other hand, for such a simple expression, you might as well+-- call 'query_' directly.+expressionDBSelect :: (Model r) => Query -> DBSelect r+expressionDBSelect q = emptyDBSelect { selFields = q }++-- | Create a 'Builder' for a rendered version of a 'DBSelect'.  This+-- can save one string copy if you want to embed one query inside+-- another as a subquery, as done by `dbProject'`, and thus need to+-- parenthesize it.  However, the function is probably not a useful+-- for end users.+buildDBSelect :: DBSelect a -> Builder+buildDBSelect dbs = gdbsQuery $ from dbs++-- | Turn a 'DBSelect' into a 'Query' suitable for the 'query' or+-- 'query_' functions.+renderDBSelect :: DBSelect a -> Query+renderDBSelect = Query . S.tail . toByteString . buildDBSelect+-- S.tail is because the rendering inserts an extra space at the beginning++catQueries :: Query -> Query -> Query -> Query+catQueries left delim right+  | qNull left  = right+  | qNull right = left+  | otherwise   = Query $ S.concat $ map fromQuery [left, delim, right]++-- | Add a where clause verbatim to a 'DBSelect'.  The clause must+-- /not/ contain the @WHERE@ keyword (which is added automatically by+-- @addWhere_@ if needed).  If the @DBSelect@ has existing @WHERE@+-- clauses, the new clause is appended with @AND@.  If the query+-- contains any @\'?\'@ characters, they will be rendered into the+-- query and matching parameters will later have to be filled in via a+-- call to 'dbSelectParams'.+addWhere_ :: Query -> DBSelect a -> DBSelect a+addWhere_ q dbs+  | qNull q = dbs+  | otherwise = dbs { selWhereKeyword = "WHERE"+                    , selWhere = catQueries (selWhere dbs) " AND " q }++-- | Add a where clause, and pre-render parameters directly into the+-- clause.  The argument @p@ must have exactly as many fields as there+-- are @\'?\'@ characters in the 'Query'.  Example:+--+-- > bars <- dbSelect c $ addWhere "bar_id = ?" (Only target_id) $+-- >                      (modelDBSelect :: DBSelect Bar)+addWhere :: (ToRow p) => Query -> p -> DBSelect a -> DBSelect a+addWhere q p dbs+  | qNull q = dbs+  | otherwise = dbs {+    selWhereKeyword = "WHERE"+  , selWhere = if qNull $ selWhere dbs+               then toQuery clause+               else toQuery $ qBuilder (selWhere dbs) <>+                    fromByteString " AND " <> clause+  }+  where clause = mconcat [fromChar '(', buildSql q p, fromChar ')']++-- | Set the @ORDER BY@ clause of a 'DBSelect'.  Example:+--+-- > dbSelect c $ setOrderBy "\"employeeName\" DESC NULLS FIRST" $+-- >                modelDBSelect+setOrderBy :: Query -> DBSelect a -> DBSelect a+setOrderBy (Query ob) dbs = dbs { selOrderBy = Query $ "ORDER BY " <> ob }++-- | Set the @LIMIT@ clause of a 'DBSelect'.+setLimit :: Int -> DBSelect a -> DBSelect a+setLimit i dbs = dbs { selLimit = fmtSql "LIMIT ?" (Only i) }++-- | Set the @OFFSET@ clause of a 'DBSelect'.+setOffset :: Int -> DBSelect a -> DBSelect a+setOffset i dbs = dbs { selOffset = fmtSql "OFFSET ?" (Only i) }++-- | Add one or more comma-separated expressions to 'selFields' that+-- produce column values without any corresponding relation in the+-- @FROM@ clause.  Type @r@ is the type into which the expression is+-- to be parsed.  Generally this will be an instance of 'FromRow' that+-- is a degenerate model (e.g., 'Only', or a tuple).+--+-- For example, to rank results by the field @value@ and compute the+-- fraction of overall value they contribute:+--+-- > r <- dbSelect c $ addExpression+-- >        "rank() OVER (ORDER BY value), value::float4/SUM(value) OVER ()"+-- >        modelDBSelect+-- >          :: IO [Bar :. (Int, Double)]+addExpression :: (Model r) => Query -> DBSelect a -> DBSelect (a :. r)+addExpression q dbs = dbs {+  selFields = if qNull $ selFields dbs then q+              else Query $ S.concat $ map fromQuery [selFields dbs, ", ", q]+  }++-- | A 'DBSelect' that returns all rows of a model.+modelDBSelect :: forall a. (Model a) => DBSelect a+modelDBSelect = r+  where mi = modelIdentifiers :: ModelIdentifiers a+        r = emptyDBSelect {+          selFields = Query $ S.intercalate ", " $ modelQColumns mi+          , selFrom = FromModel (Query $ modelQTable mi) (modelQTable mi)+          }++-- | Run a 'DBSelect' query on parameters.  The number of @\'?\'@+-- characters embedeed in various fields of the 'DBSelect' must+-- exactly match the number of fields in parameter type @p@.  Note the+-- order of arguments is such that the 'DBSelect' can be pre-rendered+-- and the parameters supplied later.  Hence, you should use this+-- version when the 'DBSelect' is static.  For dynamically modified+-- 'DBSelect' structures, you may prefer 'dbSelect'.+dbSelectParams :: (Model a, ToRow p) => DBSelect a -> Connection -> p -> IO [a]+{-# INLINE dbSelectParams #-}+dbSelectParams dbs = \c p -> map lookupRow <$> query c q p+  where -- {-# NOINLINE q #-} (crashes under GHC 7.8)+        q = renderDBSelect dbs++-- | Run a 'DBSelect' query and return the resulting models.+dbSelect :: (Model a) => Connection -> DBSelect a -> IO [a]+{-# INLINE dbSelect #-}+dbSelect c dbs = map lookupRow <$> query_ c q+  where -- {-# NOINLINE q #-} (crashes under GHC 7.8)+        q = renderDBSelect dbs++-- | Datatype that represents a connected cursor+data Cursor a = Cursor { curConn :: !Connection+                       , curName :: !Query+                       , curChunkSize :: !Query+                       , curCache :: IORef [a] }++-- | Create a 'Cursor' for the given 'DBSelect'+curSelect :: Model a => Connection -> DBSelect a -> IO (Cursor a)+curSelect c dbs = do+  name <- newTempName c+  execute_ c $+    mconcat [ "DECLARE ", name, " NO SCROLL CURSOR FOR ", q ]+  cacheRef <- newIORef []+  return $ Cursor c name "256" cacheRef+  where q = renderDBSelect dbs++-- | Fetch the next 'Model' for the underlying 'Cursor'. If the cache has+-- prefetched values, dbNext will return the head of the cache without querying+-- the database. Otherwise, it will prefetch the next 256 values, return the+-- first, and store the rest in the cache.+curNext :: Model a => Cursor a -> IO (Maybe a)+curNext Cursor{..} = do+  cache <- readIORef curCache+  case cache of+    x:xs -> do+      writeIORef curCache xs+      return $ Just x+    [] -> do+      res <- map lookupRow <$> query_ curConn (mconcat+              [ "FETCH FORWARD ", curChunkSize, " FROM ", curName])+      case res of+        [] -> return Nothing+        x:xs -> do+          writeIORef curCache xs+          return $ Just x++-- | Streams results of a 'DBSelect' and consumes them using a left-fold. Uses+-- default settings for 'Cursor' (batch size is 256 rows).+dbFold :: Model model+       => Connection -> (b -> model -> b) -> b -> DBSelect model -> IO b+dbFold c act initial dbs = do+  cur <- curSelect c dbs+  go cur initial+  where go cur accm = do+          mres <- curNext cur+          case mres of+            Nothing -> return accm+            Just res -> go cur (act accm res)++-- | Streams results of a 'DBSelect' and consumes them using a monadic+-- left-fold. Uses default settings for 'Cursor' (batch size is 256 rows).+dbFoldM :: (MonadIO m, Model model)+        => Connection -> (b -> model -> m b) -> b -> DBSelect model -> m b+dbFoldM c act initial dbs = do+  cur <- liftIO $ curSelect c dbs+  go cur initial+  where go cur accm = do+          mres <- liftIO $ curNext cur+          case mres of+            Nothing -> return accm+            Just res -> act accm res >>= go cur++-- | Streams results of a 'DBSelect' and consumes them using a monadic+-- left-fold. Uses default settings for 'Cursor' (batch size is 256 rows).+dbFoldM_ :: (MonadIO m, Model model)+         => Connection -> (model -> m ()) -> DBSelect model -> m ()+dbFoldM_ c act dbs = dbFoldM c (const act) () dbs++-- | Group the returned tuples by unique a's. Expects the query to return a's+-- in sequence -- all rows with the same value for a must be grouped together,+-- for example, by sorting the result on a's primary key column.+dbCollect :: (Model a, Model b)+           => Connection -> DBSelect (a :. b) -> IO [(a, [b])]+dbCollect c ab = dbFold c group [] ab+  where+    group :: (Model a, Model b) => [(a, [b])] -> (a :. b) -> [(a, [b])]+    group    []     (a :. b) = [(a, [b])]+    group ls@(l:_)  (a :. b) | primaryKey a /= primaryKey (fst l) = (a, [b]):ls+    group    (l:ls) (_ :. b) = (fst l, b:(snd l)):ls++-- | Create a join of the 'selFields', 'selFrom', and 'selWhere'+-- clauses of two 'DBSelect' queries.  Other fields are simply taken+-- from the second 'DBSelect', meaning fields such as 'selWith',+-- 'selGroupBy', and 'selOrderBy' in the in the first 'DBSelect' are+-- entirely ignored.+dbJoin :: forall a b.+          (Model a, Model b) =>+          DBSelect a      -- ^ First table+          -> Query        -- ^ Join keyword (@\"JOIN\"@, @\"LEFT JOIN\"@, etc.)+          -> DBSelect b   -- ^ Second table+          -> Query  -- ^ Predicate (if any) including @ON@ or @USING@ keyword+          -> DBSelect (a :. b)+dbJoin left joinOp right onClause = addWhere_ (selWhere left) right {+    selFields = Query $ S.concat [fromQuery $ selFields left, ", ",+                                  fromQuery $ selFields right]+  , selFrom = newfrom+  }+  where idab = modelIdentifiers :: ModelIdentifiers (a :. b)+        newfrom | nullFrom $ selFrom right = selFrom left+                | nullFrom $ selFrom left = selFrom right+                | otherwise = FromJoin (selFrom left) joinOp (selFrom right)+                              onClause (modelQTable idab)++-- | A version of 'dbJoin' that uses 'modelDBSelect' for the joined+-- tables.+dbJoinModels :: (Model a, Model b) =>+                Query           -- ^ Join keyword+                -> Query        -- ^ @ON@ or @USING@ predicate+                -> DBSelect (a :. b)+dbJoinModels kw on = dbJoin modelDBSelect kw modelDBSelect on++-- | Restrict the fields returned by a DBSelect to be those of a+-- single 'Model' @a@.  It only makes sense to do this if @a@ is part+-- of @something_containing_a@, but no static check is performed that+-- this is the case.  If you @dbProject@ a type that doesn't make+-- sense, you will get a runtime error from a failed database query.+dbProject :: forall a something_containing_a.+             (Model a) => DBSelect something_containing_a -> DBSelect a+{-# INLINE dbProject #-}+dbProject dbs = r+  where sela = modelDBSelect :: DBSelect a+        r = dbs { selFields = selFields sela }++-- | Like 'dbProject', but renders the entire input 'DBSelect' as a+-- subquery.  Hence, you can no longer mention fields of models other+-- than @a@ that might be involved in joins.  The two advantages of+-- this approach are 1) that you can once again join to tables that+-- were part of the original query without worrying about row aliases,+-- and 2) that all terms of the 'DBSelect' will be faithrully rendered+-- into the subquery (whereas otherwise they could get dropped by join+-- operations).  Generally you will still want to use 'dbProject', but+-- @dbProject'@ is available when needed.+dbProject' :: forall a something_containing_a.+              (Model a) => DBSelect something_containing_a -> DBSelect a+dbProject' dbs = r+  where sela = modelDBSelect :: DBSelect a+        ida = modelIdentifiers :: ModelIdentifiers a+        Just mq = modelQualifier ida+        q = toQuery $ fromChar '(' <>+            buildDBSelect dbs { selFields = selFields sela } <>+            fromByteString ") AS " <> fromByteString mq+        r = sela { selFrom = FromModel q $ modelQTable ida }++mergeFromClauses :: S.ByteString -> FromClause -> FromClause -> FromClause+mergeFromClauses canon left right =+  case go left of+    (fc, 1) -> fc+    (_, 0)  -> error $ "mergeFromClauses could not find " ++ show canon+    (_, _)  -> error $ "mergeFromClauses found duplicate " ++ show canon+  where go fc | fcCanonical fc == canon = (right, 1 :: Int)+        go (FromJoin l op r on ffc) =+          case (go l, go r) of+            ((lfc, ln), (rfc, rn)) -> (FromJoin lfc op rfc on ffc, ln + rn)+        go fc = (fc, 0)++-- | Nest two type-compatible @JOIN@ queries.  As with 'dbJoin',+-- fields of the first @JOIN@ (the @'DBSelect' (a :. b)@) other than+-- 'selFields', 'selFrom', and 'selWhere' are entirely ignored.+dbNest :: forall a b c. (Model a, Model b) =>+          DBSelect (a :. b) -> DBSelect (b :. c) -> DBSelect (a :. b :. c)+dbNest left right = addWhere_ (selWhere left) right {+    selFields = fields+  , selFrom = mergeFromClauses nameb (selFrom left) (selFrom right)+  }+  where nameb = modelQTable (modelIdentifiers :: ModelIdentifiers b)+        acols = modelQColumns (modelIdentifiers :: ModelIdentifiers a)+        colcomma c r = fromByteString c <> fromByteString ", " <> r+        fields = toQuery $ foldr colcomma (qBuilder $ selFields right)+                 acols++-- | Like 'dbNest', but projects away the middle type @b@.+dbChain :: (Model a, Model b, Model c) =>+           DBSelect (a :. b) -> DBSelect (b :. c) -> DBSelect (a :. c)+dbChain left right = dbProject $ dbNest left right
+ src/Database/PostgreSQL/ORM/Model.hs view
@@ -0,0 +1,1166 @@+{-# LANGUAGE DeriveDataTypeable #-}+{-# LANGUAGE DeriveGeneric #-}+{-# LANGUAGE DefaultSignatures #-}+{-# LANGUAGE FlexibleContexts #-}+{-# LANGUAGE FlexibleInstances #-}+{-# LANGUAGE ScopedTypeVariables #-}+{-# LANGUAGE TypeOperators #-}+{-# LANGUAGE OverloadedStrings #-}+{-# LANGUAGE GeneralizedNewtypeDeriving #-}+{-# LANGUAGE CPP #-}++-- | The main database ORM interface. This module contains+-- functionality for moving a Haskell data structure in and out of a+-- database table.+--+-- The most important feature is the 'Model' class, which encodes a+-- typed database interface (i.e., the ORM layer). This class has a+-- default implementation for types that are members of the 'Generic'+-- class (using GHC's @DeriveGeneric@ extension), provided the+-- following conditions hold:+--+--   1. The data type must have a single constructor that is defined+--      using record selector syntax.+--+--   2. The very first field of the data type must be a 'DBKey' to+--      represent the primary key.  Other orders will cause a+--      compilation error.+--+--   3. Every field of the data structure must be an instance of+--      'FromField' and 'ToField'.+--+-- If these three conditions hold and your database naming scheme+-- follows the conventions of 'defaultModelInfo'--namely that the+-- table name is the same as the type name with the first character+-- downcased, and the field names are the same as the column+-- names--then it is reasonable to have a completely empty (default)+-- instance declaration:+--+-- >   data MyType = MyType { myKey :: !DBKey+-- >                        , myName :: !S.ByteString+-- >                        , myCamelCase :: !Int+-- >                        , ...+-- >                        } deriving (Show, Generic)+-- >   instance Model MyType+--+-- The default 'modelInfo' method is called 'defaultModelInfo'. You+-- may wish to use almost all of the defaults, but tweak a few things.+-- This is easily accomplished by overriding a few fields of the+-- default structure. For example, suppose your database columns use+-- exactly the same name as your Haskell field names, but the name of+-- your database table is not the same as the name of the Haskell data+-- type. You can override the database table name (field 'modelTable')+-- as follows:+--+-- >   instance Model MyType where+-- >       modelInfo = defaultModelInfo { modelTable = "my_type" }+--+-- Finally, if you dislike the conventions followed by+-- 'defaultModelInfo', you can simply implement an alternate pattern.+-- An example of this is 'underscoreModelInfo', which strips a prefix+-- off every field name and converts everything from camel-case to+-- underscore notation:+--+-- >   instance Model MyType where+-- >       modelInfo = underscoreModelInfo "my"+--+-- The above code will associate @MyType@ with a database table+-- @my_type@ having column names @key@, @name@, @camel_case@, etc.+--+-- You can implement other patterns like 'underscoreModelInfo' by+-- calling 'defaultModelInfo' and modifying the results.+-- Alternatively, you can directly call the lower-level functions from+-- which 'defaultModelInfo' is built ('defaultModelTable',+-- 'defaultModelColumns', 'defaultModelGetPrimaryKey').+module Database.PostgreSQL.ORM.Model (+      -- * The Model class+      Model(..), ModelInfo(..), ModelIdentifiers(..), ModelQueries(..)+    , underscoreModelInfo+      -- * Data types for holding primary keys+    , DBKeyType, DBKey(..), isNullKey+    , DBRef, DBRefUnique, GDBRef(..), mkDBRef+      -- * Database operations on Models+    , findAll, findRow, save, save_, trySave, destroy, destroyByRef+      -- * Functions for accessing and using Models+    , modelName, primaryKey, modelSelectFragment+    , LookupRow(..), UpdateRow(..), InsertRow(..)+      -- * Table aliases+    , As(..), fromAs, toAs, RowAlias(..)+      -- * Low-level functions providing manual access to defaults+    , defaultModelInfo+    , defaultModelTable, defaultModelColumns, defaultModelGetPrimaryKey+    , defaultModelIdentifiers+    , defaultModelWrite+    , defaultModelQueries+    , defaultModelLookupQuery, defaultModelUpdateQuery+    , defaultModelInsertQuery, defaultModelDeleteQuery+      -- * Helper functions and miscellaneous internals+    , quoteIdent, NormalRef(..), UniqueRef(..)+    , ModelCreateInfo(..), emptyModelCreateInfo+    , defaultFromRow, defaultToRow+    , printq+      -- ** Helper classes+      -- $HelperClasses+    , GPrimaryKey0, GColumns, GDatatypeName+    , GFromRow, GToRow+    ) where++import Control.Applicative+import Control.Exception+import Control.Monad+import qualified Data.Aeson as A+import qualified Data.ByteString as S+import qualified Data.ByteString.Char8 as S8+import qualified Data.Text as T+import qualified Data.Text.Encoding as T+import Data.Char+import Data.Data+import Data.Int+import qualified Data.HashMap.Strict as H+import Data.Maybe+import Data.Monoid+import Data.List hiding (find)+import Data.String+import Database.PostgreSQL.Simple+import Database.PostgreSQL.Simple.FromField+import Database.PostgreSQL.Simple.FromRow+import Database.PostgreSQL.Simple.ToField+import Database.PostgreSQL.Simple.ToRow+import Database.PostgreSQL.Simple.Types+import Database.PostgreSQL.ORM.Validations+import GHC.Generics++import Database.PostgreSQL.Escape (quoteIdent)++-- | A type large enough to hold database primary keys.  Do not use+-- this type directly in your data structures.  Use 'DBKey' to hold a+-- `Model`'s primary key and 'DBRef' to reference the primary key of+-- another model.+type DBKeyType = Int64++-- | The type of the Haskell data structure field containing a model's+-- primary key.+--+-- Every 'Model' must have exactly one @DBKey@, and the @DBKey@ must+-- be the `Model`'s very first field in the Haskel data type+-- definition.  (The ordering is enforced by+-- 'defaultModelGetPrimaryKey', which, through use of the+-- @DeriveGeneric@ extension, fails to compile when the first field is+-- not a @DBKey@.)+--+-- Each 'Model' stored in the database should have a unique non-null+-- primary key.  However, the key is determined at the time the+-- 'Model' is inserted into the database.  While you are constructing+-- a new 'Model' to insert, you will not have its key.  Hence, you+-- should use the value @NullKey@ to let the database chose the key.+--+-- If you wish to store a `Model`'s primary key as a reference in+-- another 'Model', do not copy the 'DBKey' structure.  Use 'mkDBRef'+-- to convert the `Model`'s primary key to a foreign key reference.+data DBKey = DBKey !DBKeyType | NullKey deriving (Data, Typeable, Generic)++instance A.ToJSON DBKey where+  toJSON NullKey = A.Null+  toJSON (DBKey k) = A.toJSON k++instance A.FromJSON DBKey where+  parseJSON (A.Number a) = return $ DBKey (floor a)+  parseJSON A.Null = return NullKey+  parseJSON _ = error "Expected Number or Null"++instance Eq DBKey where+  (DBKey a) == (DBKey b) = a == b+  _         == _         = error "compare NullKey"+instance Ord DBKey where+  compare (DBKey a) (DBKey b) = compare a b+  compare _ _                 = error "compare NullKey"++instance Show DBKey where+  showsPrec n (DBKey k) = showsPrec n k+  showsPrec _ NullKey   = ("NullKey" ++)++instance FromField DBKey where+  fromField _ Nothing = pure NullKey+  fromField f bs      = DBKey <$> fromField f bs+instance ToField DBKey where+  toField (DBKey k) = toField k+  toField NullKey   = toField Null++-- | Returns 'True' when a 'DBKey' is 'NullKey'.+isNullKey :: DBKey -> Bool+isNullKey NullKey = True+isNullKey _       = False+++-- | Many operations can take either a 'DBRef' or a 'DBRefUnique'+-- (both of which consist internally of a 'DBKeyType').  Hence, these+-- two types are just type aliases to a generalized reference type+-- @GDBRef@, where @GDBRef@'s first type argument, @reftype@, is a+-- phantom type denoting the flavor of reference ('NormalRef' or+-- 'UniqueRef').+newtype GDBRef reftype table = DBRef DBKeyType+  deriving (Eq, Data, Typeable, Num, Integral, Real, Ord, Enum, Bounded, Generic)++instance A.ToJSON (GDBRef t a) where+  toJSON (DBRef k) = A.toJSON k++instance A.FromJSON (GDBRef t a) where+  parseJSON (A.Number n) = return $ DBRef (floor n)+  parseJSON _ = error "Expected Number"++instance (Model t) => Show (GDBRef rt t) where+  showsPrec n (DBRef k) = showsPrec n k+instance (Model t) => Read (GDBRef rt t) where+  readsPrec n str = map wrap $ readsPrec n str+    where wrap (k, s) = (DBRef k, s)+instance FromField (GDBRef rt t) where+  {-# INLINE fromField #-}+  fromField f bs = DBRef <$> fromField f bs+instance ToField (GDBRef rt t) where+  {-# INLINE toField #-}+  toField (DBRef k) = toField k++-- | Phantom type for instantiating 'GDBRef' that represents a one-to-many+-- relationship between tables.+data NormalRef = NormalRef deriving (Show, Data, Typeable)++-- | A @DBRef T@ represents a many-to-one relationship between tables. For+-- example, if type @A@ contains a @DBRef B@, then each @B@ is associated+-- with many @A@'s. By contrast, a @'DBRefUnique'@ represents a one-to-one+-- relationship.+--+-- @DBRef@ is a type alias of kind @* -> *@.  The type @DBRef T@+-- references an instance of type @T@ by the primary key of its+-- database row. The type argument @T@ should be an instance of+-- 'Model'.+type DBRef = GDBRef NormalRef++-- | Phantom type for instantiating 'GDBRef' that represents a one-to-one+-- relationship between tables.+data UniqueRef = UniqueRef deriving (Show, Data, Typeable)++-- | A @DBRefUnique T@ represents a one-to-one relationship between types. For+-- example, if type @A@ contains a @DBRefUnique B@, then each @A@ is associated+-- with one (or at most one) @B@, and each @B@ has one (or at most one) @A@+-- associated with it.+--+-- By contrast, a @'DBRef'@ represents a many-to-one relationship.+type DBRefUnique = GDBRef UniqueRef+-- Functionally, @DBRefUnique@ and @DBRef@ are treated the same by+-- this module.  However, other modules make a distinction.  In+-- particular, the 'modelCreateStatement' corresponding to a+-- 'DBRefUnique' will include a @UNIQUE@ constraint.++-- | Create a reference to the primary key of a 'Model', suitable for+-- storing in a 'DBRef' or 'DBRefUnique' field of a different 'Model'.+mkDBRef :: (Model a) => a -> GDBRef rt a+mkDBRef a+  | (DBKey k) <- primaryKey a = DBRef k+  | otherwise = error $ "mkDBRef " ++ S8.unpack (modelName a) ++ ": NullKey"+++-- | A @ModelInfo T@ contains the information necessary for mapping+-- @T@ to a database table.  Each @'Model'@ type has a single+-- @ModelInfo@ associated with it, accessible through the 'modelInfo'+-- method of the 'Model' class.  Note the table and column names must+-- all be unquoted in this data structure, as they will later be+-- quoted using 'quoteIdent' by the 'modelIdentifiers' method.+data ModelInfo a = ModelInfo {+    modelTable :: !S.ByteString+    -- ^ The name of the database table corresponding to this model.+    -- The default 'modelInfo' instance uses 'defaultModelTable',+    -- which is the name of your data type with the first letter+    -- downcased.+  , modelColumns :: ![S.ByteString]+    -- ^ The names of the database columns corresponding to fields of+    -- this model.  The column names should appear in the order in+    -- which the fields are defined in the Haskell data type @a@+    -- (which should also be the order in which 'modelRead' parses+    -- them to an @a@ and 'modelWrite' marshalls them).+    --+    -- Note that all queries generated by the library specify explicit+    -- column names.  Hence the order of columns does not need to+    -- match their order in the database table.  They should instead+    -- match the order of fields in the Haskell data structure.+    --+    -- The default, given by 'defaultModelColumns', is to use the+    -- Haskell field names for @a@.  This default will fail to compile+    -- if @a@ is not defined using record syntax.+  , modelPrimaryColumn :: !Int+    -- ^ The 0-based index of the primary key column in+    -- 'modelColumns'.  This should be 0 when your data structure's+    -- first field is its 'DBKey' (highly recommended, and required by+    -- 'defaultModelGetPrimaryKey').  If you customize this field, you+    -- must also customize 'modelGetPrimaryKey'--no check is made that+    -- the two are consistent.+  , modelGetPrimaryKey :: !(a -> DBKey)+    -- ^ Return the primary key of a particular model instance.  If+    -- you customize this field, you must also customize+    -- 'modelPrimaryColumn'--no check is made that the two are+    -- consistent.+  }++instance Show (ModelInfo a) where+  show a = intercalate " " [+      "Model", show $ modelTable a, show $ modelColumns a+    , show $ modelPrimaryColumn a , "?"]+++-- $HelperClasses+--+-- These classes are used internally to manipulate the 'Rep'+-- representations of 'Generic' data structures.  You should not be+-- defining instances of or using these classes directly.  The names+-- are exported so that you can include them in the context of the+-- type signatures of your functions, should you wish to make use of+-- the various @default@... funcitons in this file.++-- | This class returns the name of a datatype.+class GDatatypeName f where+  gDatatypeName :: f p -> String+instance (Datatype c) => GDatatypeName (D1 c f) where+  gDatatypeName a = datatypeName a+-- | The default name of the database table corresponding to a Haskell+-- type.  The default is the same as the type name with the first+-- letter converted to lower-case.  (The rationale is that Haskell+-- requires types to start with a capital letter, but all-lower-case+-- table names are easier to use in queries because PostgreSQL+-- generally does not require them to be quoted.)+defaultModelTable :: (Generic a, GDatatypeName (Rep a)) => a -> S.ByteString+defaultModelTable = fromString . caseFold. gDatatypeName . from+  where caseFold (h:t) = toLower h:t+        caseFold s     = s++-- | This class extracts the field names of a Haskell data structure. Only+-- defined for types with a single constructor that uses record syntax.+class GColumns f where+  gColumns :: f p -> [S.ByteString]+instance GColumns U1 where+  gColumns _ = []+instance (Selector c) => GColumns (M1 S c f) where+  gColumns s = [fromString $ selName s]+instance (GColumns a, GColumns b) => GColumns (a :*: b) where+  gColumns ~(a :*: b) = gColumns a ++ gColumns b+instance (GColumns f) => GColumns (M1 C c f) where+  gColumns ~(M1 fp) = gColumns fp+instance (GColumns f) => GColumns (M1 D c f) where+  gColumns ~(M1 fp) = gColumns fp+-- | Returns the Haskell field names in a data structure.+defaultModelColumns :: (Generic a, GColumns (Rep a)) => a -> [S.ByteString]+defaultModelColumns = gColumns . from++-- | This class extracts the first field in a data structure when the+-- field is of type 'DBKey'.  If you get a compilation error because+-- of this class, then move the 'DBKey' first in your data structure.+class GPrimaryKey0 f where+  gPrimaryKey0 :: f p -> DBKey+instance GPrimaryKey0 (S1 c (K1 i DBKey)) where+  {-# INLINE gPrimaryKey0 #-}+  gPrimaryKey0 (M1 (K1 k)) = k+instance (GPrimaryKey0 a) => GPrimaryKey0 (a :*: b) where+  {-# INLINE gPrimaryKey0 #-}+  gPrimaryKey0 (a :*: _) = gPrimaryKey0 a+instance (GPrimaryKey0 f) => GPrimaryKey0 (C1 c f) where+  {-# INLINE gPrimaryKey0 #-}+  gPrimaryKey0 (M1 fp) = gPrimaryKey0 fp+instance (GPrimaryKey0 f) => GPrimaryKey0 (D1 c f) where+  {-# INLINE gPrimaryKey0 #-}+  gPrimaryKey0 (M1 fp) = gPrimaryKey0 fp++-- | Extract the primary key of type 'DBKey' from a model when the+-- 'DBKey' is the first element of the data structure.  Fails to+-- compile if the first field is not of type 'DBKey'.+defaultModelGetPrimaryKey :: (Generic a, GPrimaryKey0 (Rep a)) => a -> DBKey+{-# INLINE defaultModelGetPrimaryKey #-}+defaultModelGetPrimaryKey = gPrimaryKey0 . from+++class GFromRow f where+  gFromRow :: RowParser (f p)+instance GFromRow U1 where+  {-# INLINE gFromRow #-}+  gFromRow = return U1+instance (FromField c) => GFromRow (K1 i c) where+  {-# INLINE gFromRow #-}+  gFromRow = K1 <$> field+instance (GFromRow a, GFromRow b) => GFromRow (a :*: b) where+  {-# INLINE gFromRow #-}+  gFromRow = (:*:) <$> gFromRow <*> gFromRow+instance (GFromRow f) => GFromRow (M1 i c f) where+  {-# INLINE gFromRow #-}+  gFromRow = M1 <$> gFromRow+-- | This function provides a 'fromRow' function for 'Generic' types,+-- suitable as a default of the 'FromRow' class.  This module uses it+-- as the default implementation of 'modelRead'.+defaultFromRow :: (Generic a, GFromRow (Rep a)) => RowParser a+{-# INLINE defaultFromRow #-}+defaultFromRow = to <$> gFromRow+++class GToRow f where+  gToRow :: f p -> [Action]+instance GToRow U1 where+  gToRow _ = []+instance (ToField c) => GToRow (K1 i c) where+  gToRow (K1 c) = [toField c]+instance (GToRow a, GToRow b) => GToRow (a :*: b) where+  gToRow (a :*: b) = gToRow a ++ gToRow b+instance (GToRow f) => GToRow (M1 i c f) where+  gToRow (M1 fp) = gToRow fp+-- | This function provides a 'toRow' function for 'Generic' types+-- that marshalls each field of the data type in the order in which it+-- appears in the type definition.  This function is /not/ a suitable+-- implementation of 'modelWrite' (since it marshals the primary key,+-- which is not supposed to be written).  However, it is required+-- internally by 'defaultModelWrite', and exposed in the unlikely+-- event it is of use to alternate generic 'modelWrite' functions.+-- You probably don't want to call this function.+defaultToRow :: (Generic a, GToRow (Rep a)) => a -> [Action]+defaultToRow = gToRow . from++-- | Removes a single element from the list at the position specified.+-- (Internal)+deleteAt :: Int -> [a] -> [a]+deleteAt 0 (_:t) = t+deleteAt n (h:t) = h:deleteAt (n-1) t+deleteAt _ _     = []++-- | Returns a series of 'Action's serializing each field of a data+-- structure (in the order of the Haskell datatype definition),+-- /except/ the primary key, since the primary key should never be+-- written to a database.  Every field must be an instance of+-- 'ToField'.+defaultModelWrite :: forall a. (Model a, Generic a, GToRow (Rep a))+                  => a -> [Action]+{-# INLINE defaultModelWrite #-}+defaultModelWrite a = deleteAt pki $ defaultToRow a+  where pki = modelPrimaryColumn (modelInfo :: ModelInfo a)++-- | The default definition of 'modelInfo'. See the documentation at+-- 'Model' for more information.  Sets 'modelTable' to the name of the+-- type with the first character converted to lower-case.  Sets+-- 'modelColumns' to the names of the Haskell field selectors.  Sets+-- 'modelPrimaryColumn' to @0@ and extracts the first field of the+-- structure for 'modelGetPrimaryKey'.  Will fail to compile unless+-- the data structure is defined with record syntax and that its first+-- field is of type 'DBKey'.+--+-- Note that defaults for the individual fields are available in+-- separate functions (e.g., 'defaultModelTable') with fewer class+-- requirements in the context, in case you want to make piecemeal use+-- of defaults.  The default for 'modelPrimaryColumn' is 0.  If you+-- overwrite that, you will need to overwrite 'modelGetPrimaryKey' as+-- well (and likely vice versa).+defaultModelInfo :: forall a.+                    (Generic a, GDatatypeName (Rep a), GColumns (Rep a)+                    , GPrimaryKey0 (Rep a)) => ModelInfo a+defaultModelInfo = m+  where m = ModelInfo { modelTable = defaultModelTable a+                      , modelColumns = defaultModelColumns a+                      , modelPrimaryColumn = 0+                      , modelGetPrimaryKey = defaultModelGetPrimaryKey+                      }+        a = undefined :: a++-- | An alternate 'Model' pattern in which Haskell type and field+-- names are converted from camel-case to underscore notation.  The+-- first argument is a prefix to be removed from field names (since+-- Haskell requires field names to be unique across data types, while+-- SQL allows the same column names to be used in different tables).+--+-- For example:+--+-- > data Bar = Bar {+-- >     barId :: !DBKey+-- >   , barNameOfBar :: !String+-- >   , barParent :: !(Maybe (DBRef Bar))+-- >   } deriving (Show, Generic)+-- >+-- > instance Model Bar where modelInfo = underscoreModelInfo "bar"+--+-- would associate type @Bar@ with a database table called @bar@ with+-- fields @id@, @name_of_bar@, and @parent@.+underscoreModelInfo :: (Generic a, GToRow (Rep a), GFromRow (Rep a)+                       , GPrimaryKey0 (Rep a), GColumns (Rep a)+                       , GDatatypeName (Rep a)) =>+                       S.ByteString -> ModelInfo a+underscoreModelInfo prefix = def {+      modelTable = toUnderscore True $ modelTable def+    , modelColumns = map fixCol $ modelColumns def+    }+  where def = defaultModelInfo+        plen = S.length prefix+        fixCol c = toUnderscore False $ stripped+          where stripped | prefix `S.isPrefixOf` c = S.drop plen c+                         | otherwise               = c++-- | Convert a name from camel-case to underscore notation.+-- I.e., names of the form "MSizeForm" are changed to "MSize_From".+-- @skipFirst@ determines if the first character should be ignored+-- in the conversion.+toUnderscore :: Bool -> S.ByteString -> S.ByteString+toUnderscore skipFirst | skipFirst = S8.pack . skip . S8.unpack+                       | otherwise = S8.pack . go True . S8.unpack+  where skip "" = ""+        skip (h:t) = toLower h : go True t+        go _ ""                      = ""+        go _ (h:t) | not (isUpper h) = h : go False t+        go True (h:t)                = toLower h : go True t+        go False (h:t)               = '_' : toLower h : go True t+++-- | SQL table and column identifiers that should be copied verbatim+-- into queries.  For normal models, these will simply be quoted+-- versions of the fields in the corresponding 'ModelInfo'.  However,+-- for special cases, the fields of this structure can contain+-- unquoted SQL including @JOIN@ keywords.  In the case of joins,+-- different elements of 'modelQColumns' may be qualified by different+-- table names.+--+-- Note that 'modelQColumns' and 'modelQPrimaryColumn' both contain+-- table-qualified names (e.g., @\"\\\"my_type\\\".\\\"key\\\"\"@),+-- while 'modelQWriteColumns' contains only the quoted column names.+data ModelIdentifiers a = ModelIdentifiers {+    modelQTable :: !S.ByteString+    -- ^ Literal SQL for the name of the table.+  , modelQColumns :: ![S.ByteString]+    -- ^ Literal SQL for each, table-qualified column.+  , modelQPrimaryColumn :: S.ByteString+    -- ^ Literal SQL for the model's table-qualified primary key+    -- column.+  , modelQWriteColumns :: [S.ByteString]+    -- ^ Literal SQL for all the columns except the primary key.+    -- These are the columns that should be included in an @INSERT@ or+    -- @UPDATE@.  Note that unlike the other fields, these column+    -- names should /not/ be table-qualified.+  , modelQualifier :: !(Maybe S.ByteString)+    -- ^ When all columns in 'modelQColumns' are qualified by the same+    -- table name, this field contains 'Just' the table name.+    -- For the ':.' type (in which different columns have different+    -- table qualifications), this field is 'Nothing'.+    --+    -- For normal models, this field will be identical to+    -- 'modelQTable'.  However, for 'As' models, 'modelQTable' will+    -- contain unquoted SQL such as @\"\\\"MyType\\\" AS+    -- \\\"my_alias\\\"\"@, in which case @modelQualifier@ will+    -- contain @'Just' \"\\\"my_alias\\\"\"@.+  , modelOrigTable :: !(Maybe S.ByteString)+    -- ^ The original, unquoted name of the table representing the+    -- model in the database.  Ordinarily, this should be the same as+    -- 'modelTable' in 'ModelInfo', but in the case of 'As' aliases,+    -- the 'modelTable' is an alias, and 'modelOrigTable' is the+    -- original table.  'Nothing' for joins.+  } deriving (Show)++-- | The default simply quotes the 'modelInfo' and 'modelColumns'+-- fields of 'ModelInfo' using 'quoteIdent'.+defaultModelIdentifiers :: ModelInfo a -> ModelIdentifiers a+defaultModelIdentifiers mi = ModelIdentifiers {+    modelQTable = qtable+  , modelQColumns = qcols+  , modelQPrimaryColumn = qcols !! pki+  , modelQWriteColumns = deleteAt pki $ map quoteIdent $ modelColumns mi+  , modelQualifier = Just qtable+  , modelOrigTable = Just $ modelTable mi+  }+  where qtable = quoteIdent (modelTable mi)+        qcol c = S.concat [qtable, ".", quoteIdent c]+        qcols = map qcol $ modelColumns mi+        pki = modelPrimaryColumn mi++-- | Standard CRUD (create\/read\/update\/delete) queries on a model.+data ModelQueries a = ModelQueries {+    modelLookupQuery :: !Query+    -- ^ A query template for looking up a model by its primary key.+    -- Expects a single query parameter, namely the 'DBKey' or 'DBRef'+    -- being looked up.+  , modelUpdateQuery :: !Query+    -- ^ A query template for updating an existing 'Model' in the+    -- database.  Expects as query parameters a value for every column+    -- of the model /except/ the primary key, followed by the primary+    -- key.  (The primary key is not written to the database, just+    -- used to select the row to change.)+  , modelInsertQuery :: !Query+    -- ^ A query template for inserting a new 'Model' in the database.+    -- The query parameters are values for all columns /except/ the+    -- primary key.  The query returns the full row as stored in the+    -- database (including the values of fields, such as the primary+    -- key, that have been chosen by the database server).+  , modelDeleteQuery :: !Query+    -- ^ A query template for deleting a 'Model' from the database.+    -- Should have a single query parameter, namely the 'DBKey' of the+    -- row to delete.+  } deriving (Show)++-- | Default SQL lookup query for a model.+defaultModelLookupQuery :: ModelIdentifiers a -> Query+defaultModelLookupQuery mi = Query $ S.concat [+  modelSelectFragment mi, " WHERE ", modelQPrimaryColumn mi, " = ?"+  ]++-- | Default SQL update query for a model.+defaultModelUpdateQuery :: ModelIdentifiers a -> Query+defaultModelUpdateQuery mi = Query $ S.concat [+    "UPDATE ", modelQTable mi, " SET "+    , S.intercalate ", " $ map (<> " = ?") $ modelQWriteColumns mi+    , " WHERE ", modelQPrimaryColumn mi, " = ?"+    , " RETURNING ", S.intercalate ", " (modelQColumns mi)+  ]++-- | Default SQL insert query for a model.+defaultModelInsertQuery :: ModelIdentifiers a -> Query+defaultModelInsertQuery mi+  | null (modelQWriteColumns mi) = Query $ S.concat [+    "INSERT INTO ", modelQTable mi, " DEFAULT VALUES RETURNING "+    , S.intercalate ", " $ modelQColumns mi ]+  | otherwise = Query $ S.concat $ [+  "INSERT INTO ", modelQTable mi+  , " (", S.intercalate ", " $ modelQWriteColumns mi+  , ") VALUES (", S.intercalate ", " $ map (const "?") $ modelQWriteColumns mi+  , ") RETURNING ", S.intercalate ", " $ modelQColumns mi+  ]++-- | Default SQL delete query for a model.+defaultModelDeleteQuery :: ModelIdentifiers a -> Query+defaultModelDeleteQuery mi = Query $ S.concat [+  "DELETE FROM ", modelQTable mi+  , " WHERE ", modelQPrimaryColumn mi, " = ?"+  ]++-- | The default value of 'modelQueries'.+defaultModelQueries :: ModelIdentifiers a -> ModelQueries a+defaultModelQueries mi = ModelQueries {+    modelLookupQuery = defaultModelLookupQuery mi+  , modelUpdateQuery = defaultModelUpdateQuery mi+  , modelInsertQuery = defaultModelInsertQuery mi+  , modelDeleteQuery = defaultModelDeleteQuery mi+  }++-- | Extra information for "Database.PostgreSQL.ORM.CreateTable".  You+-- probably don't need to use this.+data ModelCreateInfo a = ModelCreateInfo {+    modelCreateColumnTypeExceptions :: ![(S.ByteString, S.ByteString)]+    -- ^ A list of (column-name, type) pairs for which you want to+    -- override the default.+  , modelCreateExtraConstraints :: !S.ByteString+    -- ^ Extra constraints to stick at the end of the @CREATE TABLE@+    -- statement.+  } deriving (Show)++-- | A 'ModelCreateInfo' that doesn't imply any extra constraints or+-- exceptions.+emptyModelCreateInfo :: ModelCreateInfo a+emptyModelCreateInfo = ModelCreateInfo {+    modelCreateColumnTypeExceptions = []+  , modelCreateExtraConstraints = S.empty+  }++-- | The class of data types that represent a database table.  This+-- class conveys information necessary to move a Haskell data+-- structure in and out of a database table.  The most important field+-- is 'modelInfo', which describes the database table and column+-- names.  'modelInfo' has a reasonable default implementation for+-- types that are members of the 'Generic' class (using GHC's+-- @DeriveGeneric@ extension), provided the following conditions hold:+--+--   1. The data type must have a single constructor that is defined+--      using record selector syntax.+--+--   2. The very first field of the data type must be a 'DBKey' to+--      represent the primary key.  Other orders will cause a+--      compilation error.+--+--   3. Every field of the data structure must be an instance of+--      'FromField' and 'ToField'.+--+-- If these three conditions hold and your database naming scheme+-- follows the conventions of 'defaultModelInfo'--namely that the+-- table name is the same as the type name with the first character+-- downcased, and the field names are the same as the column+-- names--then it is reasonable to have a completely empty (default)+-- instance declaration:+--+-- >   data MyType = MyType { myKey :: !DBKey+-- >                        , myName :: !S.ByteString+-- >                        , myCamelCase :: !Int+-- >                        , ...+-- >                        } deriving (Show, Generic)+-- >   instance Model MyType+--+-- The default 'modelInfo' method is called 'defaultModelInfo'.  You+-- may wish to use almost all of the defaults, but tweak a few things.+-- This is easily accomplished by overriding a few fields of the+-- default structure.  For example, suppose your database columns use+-- exactly the same name as your Haskell field names, but the name of+-- your database table is not the same as the name of the Haskell data+-- type.  You can override the database table name (field+-- 'modelTable') as follows:+--+-- >   instance Model MyType where+-- >       modelInfo = defaultModelInfo { modelTable = "my_type" }+--+-- Finally, if you dislike the conventions followed by+-- 'defaultModelInfo', you can simply implement an alternate pattern.+-- An example of this is 'underscoreModelInfo', which strips a prefix+-- off every field name and converts everything from camel-case to+-- underscore notation:+--+-- >   instance Model MyType where+-- >       modelInfo = underscoreModelInfo "my"+--+-- The above code will associate @MyType@ with a database table+-- @my_type@ having column names @key@, @name@, @camel_case@, etc.+--+-- You can implement other patterns like 'underscoreModelInfo' by+-- calling 'defaultModelInfo' and modifying the results.+-- Alternatively, you can directly call the lower-level functions from+-- which 'defaultModelInfo' is built ('defaultModelTable',+-- 'defaultModelColumns', 'defaultModelGetPrimaryKey').+class Model a where+  -- | @modelInfo@ provides information about how the Haskell data+  -- type is stored in the database, in the form of a 'ModelInfo' data+  -- structure.  Among other things, this structure specifies the name+  -- of the database table, the names of the database columns+  -- corresponding to the Haskell data structure fields, and the+  -- position of the primary key in both the database columns and the+  -- Haskell data structure.+  modelInfo :: ModelInfo a+  default modelInfo :: (Generic a, GDatatypeName (Rep a), GColumns (Rep a)+                       , GPrimaryKey0 (Rep a)) => ModelInfo a+  {-# INLINE modelInfo #-}+  modelInfo = defaultModelInfo++  -- | 'modelIdentifiers' contains the table and column names verbatim+  -- as they should be inserted into SQL queries.  For normal models,+  -- these are simply double-quoted (with 'quoteIdent') versions of+  -- the names in 'modelInfo', with the column names qualified by the+  -- double-quoted table name.  However, for special cases such as+  -- join relations (with ':.')  or row aliases (with 'As'),+  -- 'modelIdentifiers' can modify the table name with unquoted SQL+  -- identifiers (such as @JOIN@ and @AS@) and change the qualified+  -- column names appropriately.+  modelIdentifiers :: ModelIdentifiers a+  {-# INLINE modelIdentifiers #-}+  modelIdentifiers = defaultModelIdentifiers modelInfo++  -- | @modelRead@ converts from a database 'query' result to the+  -- Haskell data type of the @Model@, namely @a@.  Note that if type+  -- @a@ is an instance of 'FromRow', a fine definition of @modelRead@+  -- is @modelRead = fromRow@.  The default is to construct a row+  -- parser using the 'Generic' class.  However, it is crucial that+  -- the columns be parsed in the same order they are listed in the+  -- 'modelColumns' field of @a@'s 'ModelInfo' structure, and this+  -- should generally be the same order they are defined in the+  -- Haskell data structure.  Hence @modelRead@ should generally look+  -- like:+  --+  -- @+  --   -- Call 'field' as many times as there are fields in your type+  --   modelRead = Constructor \<$> 'field' \<*> 'field' \<*> 'field'+  -- @+  modelRead :: RowParser a+  default modelRead :: (Generic a, GFromRow (Rep a)) => RowParser a+  {-# INLINE modelRead #-}+  modelRead = defaultFromRow++  -- | Marshal all fields of @a@ /except/ the primary key.  As with+  -- 'modelRead', the fields must be marshalled in the same order the+  -- corresponding columns are listed in 'modelColumns', only with the+  -- primary key (generally column 0) deleted.+  --+  -- Do /not/ define this as 'toRow', even if @a@ is an instance of+  -- 'ToRow', because 'toRow' would include the primary key.+  -- Similarly, do /not/ define this as 'defaultToRow'.  On the other+  -- hand, it is reasonable for @modelWrite@ to return an error for+  -- degenerate models (such as joins) that should never be 'save'd.+  modelWrite :: a -> [Action]+  default modelWrite :: (Generic a, GToRow (Rep a)) => a -> [Action]+  {-# INLINE modelWrite #-}+  modelWrite = defaultModelWrite++  -- | @modelQueries@ provides pre-formatted 'Query' templates for+  -- 'findRow', 'save', and 'destroy'.  The default 'modelQueries'+  -- value is generated from 'modelIdentifiers' and should not be+  -- modified.  However, for degenerate tables (such as joins created+  -- with ':.'), it is reasonable to make 'modelQueries' always throw+  -- an exception, thereby disallowing ordinary queries and requiring+  -- use of more general query functions.+  --+  -- This method should either throw an exception or use the default+  -- implementation.+  modelQueries :: ModelQueries a+  {-# INLINE modelQueries #-}+  modelQueries = defaultModelQueries modelIdentifiers++  -- | Extra constraints, if any, to place in a @CREATE TABLE@+  -- statement.  Only used by "Database.PostgreSQL.ORM.CreateTable".+  modelCreateInfo :: ModelCreateInfo a+  modelCreateInfo = emptyModelCreateInfo++  -- | Perform a validation of the model, returning any errors if+  -- it is invalid.+  modelValid :: a -> ValidationError+  modelValid = const mempty++-- | Degenerate instances of 'Model' for types in the 'ToRow' class+-- are to enable extra 'ToRow' types to be included with ':.' in the+-- result of 'dbSelect' queries.+degen_err :: a+degen_err = error "Attempt to use degenerate ToRow instance as Model"+#define DEGENERATE(ctx,t)             \+instance ctx => Model t where {       \+  modelInfo = degen_err;              \+  modelIdentifiers = degen_err;       \+  modelRead = fromRow;                \+  modelWrite _ = degen_err;           \+  modelCreateInfo = degen_err; }++DEGENERATE(FromField t, (Only t))+DEGENERATE(FromField t, [t])+DEGENERATE((FromField a, FromField b), (a, b))+DEGENERATE((FromField a, FromField b, FromField c), (a, b, c))+DEGENERATE((FromField a, FromField b, FromField c, FromField d), (a, b, c, d))+DEGENERATE((FromField a, FromField b, FromField c, FromField d, FromField e), \+           (a, b, c, d, e))++#undef DEGEN_ERR+#undef DEGENERATE++-- | A degenerate model that lifts any model to a Maybe version. Returns+-- 'Nothing' on a parse failure. Useful, for example, for performing outer+-- joins:+-- @+-- dbJoin modelDBSelect "LEFT OUTER JOIN"+--        (addWhere 'foo = 123' $ modelDBSelect)+--        "USING a.id = b.a_id" :: (A :. Maybe B)+-- @+--+instance forall a. Model a => Model (Maybe a) where+  modelInfo = mi_a { modelGetPrimaryKey = getPrimaryKey }+    where mi_a = modelInfo :: ModelInfo a+          getPrimaryKey Nothing  = NullKey+          getPrimaryKey (Just a) = modelGetPrimaryKey mi_a a++  modelIdentifiers = mi_a { modelQTable = modelQTable mi_a }+    where mi_a = modelIdentifiers :: ModelIdentifiers a++  modelQueries = mi_a { modelLookupQuery = modelLookupQuery mi_a }+    where mi_a = modelQueries :: ModelQueries a++  modelCreateInfo = error+    "Attempt to use degenerate Maybe (Model a) instance for ModelCreateInfo"++  modelValid = maybe mempty modelValid++  modelWrite = maybe [] modelWrite++  modelRead =+    Just `fmap` (modelRead :: RowParser a)+    <|> do+      let n = length $ modelColumns (modelInfo :: ModelInfo a)+      replicateM_ n (field :: RowParser AnyField)+      return Nothing++-- | AnyField parses (simply by consuming) any SQL column.+data AnyField = AnyField++instance FromField AnyField where+  fromField _ _ = pure AnyField++joinModelIdentifiers :: forall a b. (Model a, Model b)+                     => ModelIdentifiers (a :. b)+joinModelIdentifiers = r+  where r = ModelIdentifiers {+              modelQTable = qtable+            , modelQColumns = modelQColumns mia ++ modelQColumns mib+            , modelQWriteColumns = error "attempt to write join relation"+            , modelQPrimaryColumn =+              error "attempt to use primary key of join relation"+            , modelQualifier = Nothing+            , modelOrigTable = Nothing+          }+        qtable | S.null $ modelQTable mib = modelQTable mia+               | S.null $ modelQTable mia = modelQTable mib+               | otherwise = S.concat [modelQTable mia, " CROSS JOIN "+                                      , modelQTable mib]+        mia = modelIdentifiers :: ModelIdentifiers a+        mib = modelIdentifiers :: ModelIdentifiers b++-- | A degenerate instance of model representing a database join.  The+-- ':.' instance does not allow normal model operations such as+-- 'findRow', 'save', and 'destroy'.  Attempts to use such functions+-- will result in an exception.+instance (Model a, Model b) => Model (a :. b) where+  modelInfo = error "attempt to access ModelInfo of join type :."+  modelIdentifiers = joinModelIdentifiers+  modelRead = (:.) <$> modelRead <*> modelRead+  modelWrite _ = error "attempt to write join type :. as a normal Model"+  modelQueries = error "attempt to perform standard query on join type :."+++class GUnitType f where+  gUnitTypeName :: f p -> String+instance GUnitType (C1 c U1) where+  gUnitTypeName _ = error "gUnitTypeName"+instance GUnitType V1 where+  gUnitTypeName _ = error "gUnitTypeName"+instance (Datatype c, GUnitType f) => GUnitType (D1 c f) where+  gUnitTypeName = datatypeName++-- | The class of types that can be used as tags in as 'As' alias.+-- Such types should be unit types--in other words, have exactly one+-- constructor where the constructor is nullary (take no arguments).+-- The reason for this class is that the 'Model' instance for 'As'+-- requires a way to extract the name of the row alias without having+-- a concrete instance of the type.  This is provided by the+-- 'rowAliasName' method (which must be non-strict).+class RowAlias a where+  rowAliasName :: g a row -> S.ByteString+  -- ^ Return the SQL identifier for the row alias.  This method must+  -- be non-strict in its argument.  Hence, it should discard the+  -- argument and return the name of the alias.  For example:+  --+  -- > {-# LANGUAGE OverloadedStrings #-}+  -- >+  -- > data My_alias = My_alias+  -- > instance RowAlias My_alias where rowAliasName _ = "my_alias"+  --+  -- Keep in mind that PostgreSQL folds unquoted identifiers to+  -- lower-case.  However, this library quotes row aliases in @SELECT@+  -- statements, thereby preserving case.  Hence, if you want to call+  -- construct a @WHERE@ clause without double-quoting row aliases in+  -- your 'Query', you should avoid capital letters in alias names.+  --+  -- A default implementation of @rowAliasName@ exists for unit types+  -- (as well as empty data declarations) in the 'Generic' class.  The+  -- default converts the first character of the type name to+  -- lower-case, following the logic of 'defaultModelTable'.+  default rowAliasName :: (Generic a, GUnitType (Rep a)) =>+                          g a row -> S.ByteString+  rowAliasName _ = fromString $ caseFold $ gUnitTypeName . from $ a+    where caseFold (h:t) = toLower h:t -- fold first character only+          caseFold []    = []+          a = undefined :: a++-- | The newtype @As@ can be wrapped around an existing type to give+-- it a table name alias in a query.  This is necessary when a model+-- is being joined with itself, to distinguish the two joined+-- instances of the same table.+--+-- For example:+--+-- @{-\# LANGUAGE OverloadedStrings #-}+--+--data X = X+--instance 'RowAlias' X where rowAliasName = const \"x\"+--+-- \  ...+--    r <- 'dbSelect' c $ addWhere_ \"bar.bar_key = x.bar_parent\" modelDBSelect+--         :: IO [Bar :. As X Bar]+-- @+newtype As alias row = As { unAs :: row }+instance (RowAlias alias, Show row) => Show (As alias row) where+  showsPrec d as@(As row) = showParen (d > 10) $ \rest ->+    "As " ++ S8.unpack (rowAliasName as) +++    " (" ++ showsPrec 11 row (")" ++ rest)+++-- | @fromAs@ extracts the @row@ from an @'As' alias row@, but+-- constrains the type of @alias@ to be the same as its first argument+-- (which is non-strict).  This can save you from explicitly+-- specifying types.  For example:+--+-- > data X = X deriving (Generic)+-- > instance RowAlias X where rowAliasName = const "x"+-- >+-- > ...+-- >   r <- map (\(b1 :. b2) -> (b1, fromAs X b2)) <$>+-- >       dbSelect c $ addWhere \"bar.bar_key = x.bar_parent\" modelDBSelect+fromAs :: alias -> As alias row -> row+{-# INLINE fromAs #-}+fromAs _ (As row) = row++-- | A type-restricted wrapper around the 'As' constructor, under the+-- same rationale as 'fromAs'.  Not strict in its first argument.+toAs :: alias -> row -> As alias row+{-# INLINE toAs #-}+toAs _ = As++aliasModelInfo :: forall a alias.+                  (Model a, RowAlias alias) =>+                  ModelInfo a -> ModelInfo (As alias a)+aliasModelInfo mi = r+  where alias = rowAliasName (undefined :: As alias a)+        r = mi { modelTable = alias+               , modelGetPrimaryKey = modelGetPrimaryKey mi . unAs+               }++aliasModelIdentifiers :: forall a alias. (Model a, RowAlias alias)+                      => ModelInfo a -> ModelIdentifiers (As alias a)+aliasModelIdentifiers mi+  | not ok    = error $ "aliasModelIdentifiers: degenerate model " +++                show (modelQTable ida )+  | otherwise = r+  where r = ModelIdentifiers {+            modelQTable = S.concat [quoteIdent orig, " AS ", alias]+          , modelQColumns = qcols+          , modelQPrimaryColumn = qcols !! pki+          , modelQWriteColumns = deleteAt pki qcols+          , modelQualifier = Just alias+          , modelOrigTable = Just orig+          }+        ida = modelIdentifiers :: ModelIdentifiers a+        ok = Just (modelQTable ida) == modelQualifier ida+             && isJust (modelOrigTable ida)+        Just orig = modelOrigTable ida+        alias = quoteIdent $ rowAliasName (undefined :: As alias a)+        qcol c = S.concat [alias, ".", quoteIdent c]+        qcols = map qcol $ modelColumns mi+        pki = modelPrimaryColumn mi++-- | A degenerate instance of 'Model' that re-names the row with a SQL+-- @AS@ keyword.  This is primarily useful when joining a model with+-- itself.  Hence, standard operations ('findRow', 'save', 'destroy')+-- are not allowed on 'As' models.+instance (Model a, RowAlias as) => Model (As as a) where+  {-# INLINE modelInfo #-}+  modelInfo = aliasModelInfo modelInfo+  {-# INLINE modelRead #-}+  modelRead = As <$> modelRead+  modelWrite = error "attempt to write \"As\" alias as normal Model"+  {-# INLINE modelIdentifiers #-}+  modelIdentifiers = aliasModelIdentifiers modelInfo+  modelQueries = error "attempt to perform standard query on AS table alias"+++-- | Lookup the 'modelTable' of a 'Model' (@modelName _ = 'modelTable'+-- ('modelInfo' :: 'ModelInfo' a)@).+modelName :: forall a. (Model a) => a -> S.ByteString+{-# INLINE modelName #-}+modelName _ = modelTable (modelInfo :: ModelInfo a)++-- | Lookup the primary key of a 'Model'.+primaryKey :: (Model a) => a -> DBKey+{-# INLINE primaryKey #-}+primaryKey a = modelGetPrimaryKey modelInfo a++-- | Generate a SQL @SELECT@ statement with no @WHERE@ predicate.  For+-- example, 'defaultModelLookupQuery' consists of+-- @modelSelectFragment@ followed by \"@WHERE@ /primary-key/ = ?\".+modelSelectFragment :: ModelIdentifiers a -> S.ByteString+modelSelectFragment mi = S.concat [+ "SELECT ", S.intercalate ", " $ modelQColumns mi, " FROM ", modelQTable mi ]++-- | A newtype wrapper in the 'FromRow' class, permitting every model+-- to be used as the result of a database query.+newtype LookupRow a = LookupRow { lookupRow :: a } deriving (Show)+instance (Model a) => FromRow (LookupRow a) where+  fromRow = LookupRow <$> modelRead++-- | A newtype wrapper in the 'ToRow' class, which marshalls every+-- field except the primary key.  For use with 'modelInsertQuery'.+newtype InsertRow a = InsertRow a deriving (Show)+instance (Model a) => ToRow (InsertRow a) where+  toRow (InsertRow a) = modelWrite a++-- | A newtype wrapper in the 'ToRow' class, which marshalls every+-- field except the primary key, followed by the primary key.  For use+-- with 'modelUpdateQuery'.+newtype UpdateRow a = UpdateRow a deriving (Show)+instance (Model a) => ToRow (UpdateRow a) where+  toRow (UpdateRow a) = toRow $ InsertRow a :. Only (primaryKey a)++-- | Dump an entire model.  Useful for development and debugging only,+-- as every row will be read into memory before the function returns.+--+-- Note that unlike the other primary model operations, it is OK to+-- call 'findAll' even on degenerate models such as 'As' and ':.'.+findAll :: forall r. (Model r) => Connection -> IO [r]+findAll c = action+  where mi = modelIdentifiers :: ModelIdentifiers r+        q = Query $ modelSelectFragment mi+        action = map lookupRow <$> query_ c q++-- | Follow a 'DBRef' or 'DBRefUnique' and fetch the target row from+-- the database into a 'Model' type @r@.+findRow :: forall r rt. (Model r) => Connection -> GDBRef rt r -> IO (Maybe r)+findRow c k = action+  where qs = modelQueries :: ModelQueries r+        action = do rs <- query c (modelLookupQuery qs) (Only k)+                    case rs of [r] -> return $ Just $ lookupRow $ r+                               _   -> return Nothing++-- | Like 'trySave' but instead of returning an 'Either', throws a+-- 'ValidationError' if the 'Model' is invalid.+save :: (Model r)+     => Connection -> r -> IO r+save c r = do+  eResp <- trySave c r+  case eResp of+    Right resp -> return resp+    Left  errs -> throwIO errs++-- | 'save' but returning '()' instead of the saved model.+save_ :: (Model r)+      => Connection -> r -> IO ()+save_ c r = void $ save c r++-- | Write a 'Model' to the database.  If the primary key is+-- 'NullKey', the item is written with an @INSERT@ query, read back+-- from the database, and returned with its primary key filled in.  If+-- the primary key is not 'NullKey', then the 'Model' is written with+-- an @UPDATE@ query and returned as-is.+--+-- If the 'Model' is invalid (i.e. the return value of 'modelValid' is+-- non-empty), a list of 'InvalidError' is returned instead.+trySave :: forall r. Model r+        => Connection -> r -> IO (Either ValidationError r)+trySave c r | not . H.null $ validationErrors errors = return $ Left errors+            | NullKey <- primaryKey r = do+                  rs <- query c (modelInsertQuery qs) (InsertRow r)+                  case rs of [r'] -> return $ Right $ lookupRow r'+                             _    -> fail "save: database did not return row"+            | otherwise = do+                  rows <- query c (modelUpdateQuery qs) (UpdateRow r)+                  case rows of [r'] -> return $ Right $ lookupRow r'+                               _     -> fail $ "save: database updated "+                                          ++ show (length rows)+                                          ++ " records"+  where qs = modelQueries :: ModelQueries r+        errors = modelValid r++-- | Remove the row corresponding to a particular data structure from+-- the database.  This function only looks at the primary key in the+-- data structure.  It is an error to call this function if the+-- primary key is not set.+destroy :: forall a. (Model a)+  => Connection -> a -> IO (Either ValidationError Bool)+destroy c a =+  case primaryKey a of+    NullKey -> fail "destroy: NullKey"+    DBKey k -> destroyByRef_ "destroy" c (DBRef k :: DBRef a)++-- | Remove a row from the database without fetching it first.+destroyByRef :: forall a rt. (Model a)+  => Connection -> GDBRef rt a -> IO (Either ValidationError Bool)+destroyByRef = destroyByRef_ "destroyByRef"++destroyByRef_ :: forall a rt. (Model a)+  => T.Text -> Connection -> GDBRef rt a -> IO (Either ValidationError Bool)+destroyByRef_ msg c a = action+  where mq     = modelQueries     :: ModelQueries a+        mi     = modelIdentifiers :: ModelIdentifiers a+        pkCol  = modelQPrimaryColumn mi+        action = do+            n <- execute c (modelDeleteQuery mq) (Only a)+            return $ case n of+                0 -> Right False+                1 -> Right True+                _ -> Left $ validationError (T.decodeUtf8 pkCol) $+                    msg <> ": DELETE modified " <> T.pack (show n) <>+                    " rows. This may indicate that your primary key" <>+                    " accessor field is not actually a primary key."++-- | Print to stdout the query statement.+printq :: Query -> IO ()+printq (Query bs) = S8.putStrLn bs
+ src/Database/PostgreSQL/ORM/SqlType.hs view
@@ -0,0 +1,108 @@+{-# LANGUAGE CPP #-}+{-# LANGUAGE FlexibleInstances #-}+{-# LANGUAGE OverloadedStrings #-}+{-# LANGUAGE ScopedTypeVariables #-}++module Database.PostgreSQL.ORM.SqlType (SqlType(..), getTypeOid) where++import qualified Data.ByteString as S+import qualified Data.ByteString.Lazy as L+import Data.Int+import Data.Monoid+import qualified Data.Text as ST+import qualified Data.Text.Lazy as LT+import Data.Time+import Data.Typeable+import qualified Data.Vector as V+import Database.PostgreSQL.Simple+import Database.PostgreSQL.Simple.FromField+import Database.PostgreSQL.Simple.Time+import Database.PostgreSQL.Simple.ToField+import Database.PostgreSQL.Simple.TypeInfo.Static+import Database.PostgreSQL.Simple.Types++import Database.PostgreSQL.ORM.Model++newtype ExtractTypeOid = ExtractTypeOid Oid+instance FromField ExtractTypeOid where+  fromField f _ = return $ ExtractTypeOid $ typeOid f++-- | Retreive the 'Oid' corresponding to a type.  You can subsequently+-- use the 'Oid' to call 'getTypeInfo' for more information on the+-- type.+getTypeOid :: Connection -> S.ByteString -> IO Oid+getTypeOid c tname = do+  [Only (ExtractTypeOid ti)] <- query_ c $ Query $ "SELECT NULL :: " <> tname+  return ti++-- | The class of Haskell types that can be converted to and from a+-- particular SQL type.  For most instances, you only need to define+-- 'sqlBaseType'.+class (ToField a, FromField a) => SqlType a where+  sqlBaseType :: a -> S.ByteString+  -- ^ The name of the SQL type corresponding to Haskell type @a@,+  -- when a value of @a@ can be null.  This is the SQL type to and+  -- from which a @'Maybe' a@ will be converted (where 'Nothing'+  -- corresponds to the SQL value null).+  sqlType :: a -> S.ByteString+  -- ^ The name of the SQL type corresponding to Haskell type @a@,+  -- when @a@ is not wrapped in 'Maybe' and hence cannot be null.  If+  -- @sqlType@ is unspecified, the default is to append \"@NOT NULL@\"+  -- to 'sqlBaseType'.+  {-# INLINE sqlType #-}+  sqlType _ = (sqlBaseType (undefined :: a)) <> " NOT NULL"++#define TYPE(hs, sql) \+    instance SqlType (hs) where sqlBaseType _ = typname (sql)+TYPE(Bool, bool)+TYPE(Double, float8)+TYPE(Float, float4)+TYPE(Int16, int2)+TYPE(Int32, int4)+TYPE(Int64, int8)+TYPE(S.ByteString, text)+TYPE(L.ByteString, text)+TYPE(ST.Text, text)+TYPE(LT.Text, text)+TYPE(Oid,oid)+TYPE(LocalTime, timestamp)+TYPE(ZonedTime, timestamptz)+TYPE(TimeOfDay, time)+TYPE(UTCTime, timestamptz)+TYPE(Day, date)+TYPE(Date, date)+TYPE(ZonedTimestamp, timestamptz)+TYPE(UTCTimestamp, timestamptz)+TYPE(LocalTimestamp, timestamp)+TYPE(String, text)+TYPE(Binary S.ByteString, bytea)+TYPE(Binary L.ByteString, bytea)++#undef TYPE++instance SqlType DBKey where+  sqlType _ = "bigserial UNIQUE NOT NULL PRIMARY KEY"+  sqlBaseType _ = error "DBKey should not be wrapped in type"++instance (SqlType a) => SqlType (Maybe a) where+  sqlType _ = sqlBaseType (undefined :: a)+  sqlBaseType _ = error "Table field Maybe should not be wrapped in other type"++instance (Typeable a, SqlType a) => SqlType (V.Vector a) where+  sqlBaseType _ = sqlBaseType (undefined :: a) <> "[]"++instance (Model a) => SqlType (DBRef a) where+  sqlBaseType (DBRef k) = sqlBaseType k <> ref+    where t = modelInfo :: ModelInfo a+          Just orig = modelOrigTable (modelIdentifiers :: ModelIdentifiers a)+          ref = S.concat [+              " REFERENCES ", quoteIdent orig, "("+              , quoteIdent (modelColumns t !! modelPrimaryColumn t), ")" ]++instance (Model a) => SqlType (DBRefUnique a) where+  sqlBaseType (DBRef k) = sqlBaseType k <> ref+    where t = modelInfo :: ModelInfo a+          Just orig = modelOrigTable (modelIdentifiers :: ModelIdentifiers a)+          ref = S.concat [+              " UNIQUE REFERENCES ", quoteIdent orig , "("+              , quoteIdent (modelColumns t !! modelPrimaryColumn t), ")" ]
+ src/Database/PostgreSQL/ORM/Validations.hs view
@@ -0,0 +1,60 @@+{-# LANGUAGE CPP, FlexibleContexts, DeriveDataTypeable, OverloadedStrings #-}+module Database.PostgreSQL.ORM.Validations where++import Control.Exception+import Data.Aeson+import qualified Data.HashMap.Strict as H+#if __GLASGOW_HASKELL__ < 710+import Data.Monoid+#endif+import qualified Data.Text as T+import Data.Typeable+#if __GLASGOW_HASKELL >= 806+import Data.Semigroup+#endif++newtype ValidationError = ValidationError+  { validationErrors :: H.HashMap T.Text [T.Text] } deriving (Show, Typeable)++instance Exception ValidationError++#if __GLASGOW_HASKELL__ >= 806+instance Semigroup ValidationError where+  ein <> zwei = ValidationError $!+    H.unionWith mappend (validationErrors ein) (validationErrors zwei)+#endif++instance Monoid ValidationError where+  mempty = ValidationError mempty+#if __GLASGOW_HASKELL < 806+  mappend ein zwei = ValidationError $!+    H.unionWith mappend (validationErrors ein) (validationErrors zwei)+#endif++instance ToJSON ValidationError where+  toJSON = toJSON . validationErrors++instance FromJSON ValidationError where+  parseJSON val = ValidationError `fmap` parseJSON val++type ValidationFunc a = a -> ValidationError++validationError :: T.Text -> T.Text -> ValidationError+validationError columnName description =+    ValidationError $ H.singleton columnName [description]++validate :: (a -> Bool)+         -> T.Text -- ^ Column name+         -> T.Text -- ^ Error description+         -> ValidationFunc a+validate validator columnName desc = \a ->+  if validator a+    then mempty+    else validationError columnName desc++validateNotEmpty :: (a -> T.Text)+                 -> T.Text+                 -> T.Text+                 -> ValidationFunc a+validateNotEmpty accessor = validate (not . T.null . accessor)+
+ static/CompilerUtils.hs view
@@ -0,0 +1,97 @@+{-# LANGUAGE OverloadedStrings, ScopedTypeVariables #-}+module CompilerUtils (+  fromList, Migration(..), MigrationMap, compiledMain+) where++import Control.Exception (SomeException, catch)+import Control.Monad (forM_, void)+import Data.Map (Map, fromList)+import qualified Data.Map as M+import Database.PostgreSQL.Simple+  (Connection, Only(..), execute, query_, begin, commit)+import Database.PostgreSQL.Migrations (connectEnv)+import Database.PostgreSQL.Migrate (initializeDb)+import System.Environment (getArgs, getProgName)++type Version = String++data Migration = Migration { migName :: String+                           , migUp :: Connection -> IO ()+                           , migDown :: Connection -> IO ()+                           }++type MigrationMap = Map Version Migration++compiledMain :: MigrationMap -> IO ()+compiledMain migrations = do+  args <- getArgs+  case args of+    "init":[] -> initializeDb+    "list":[] -> listMigrations migrations+    "migrate":[] -> runMigrations migrations+    "rollback":[] -> runRollback migrations+    _ -> do+      progName <- getProgName+      putStrLn $ "Usage: " ++ progName ++ " migrate|rollback"+      putStrLn $ "       " ++ progName ++ " list"+      putStrLn $ "       " ++ progName ++ " init"++listMigrations :: MigrationMap -> IO ()+listMigrations migrations =+  forM_ (M.toAscList migrations) $ \(_, Migration name _ _) -> putStrLn name++-- | Runs all new migrations in a given directory and dumps the+-- resulting schema to a file \"schema.sql\" in the migrations+-- directory.+--+-- Determining which migrations to run is done by querying the database for the+-- largest version in the /schema_migrations/ table, and choosing all+-- migrations in the given directory with higher versions.+runMigrations :: MigrationMap -> IO ()+runMigrations migrationsIn = do+  conn <- connectEnv+  res <- query_ conn+         "select version from schema_migrations order by version desc limit 1"+  let latestVersion = case res of+                        [] -> ""+                        (Only latest):_ -> latest+  let migrations = M.toAscList $+        M.filterWithKey (\k _ -> k > latestVersion) migrationsIn+  forM_ migrations (doone conn)+  where doone conn (version, Migration name up down) = do+          putStrLn $ "=== Running Migration " ++ name+          ok <- catch+            (do+                begin conn+                void $ execute conn "insert into schema_migrations values(?)"+                  (Only version)+                up conn+                commit conn+                return True)+            (\(e :: SomeException) -> return False)+          if ok+            then putStrLn "=== Success"+            else putStrLn "=== Migration Failed!"++runRollback :: MigrationMap -> IO ()+runRollback migrations = do+  conn <- connectEnv+  res <- query_ conn+          "select version from schema_migrations order by version desc limit 1"+  case res of+    [] -> putStrLn "=== DB Fully Rolled Back!"+    (Only latest):_ -> do+      let (Migration name _ down) = migrations M.! latest+      putStrLn $ "=== Running Rollback " ++ name+      ok <- catch+        (do+            begin conn+            down conn+            void $ execute conn "delete from schema_migrations where version = ?"+              (Only latest)+            commit conn+            return True)+        (\(e :: SomeException) -> return False)+      if ok+        then putStrLn "=== Success"+        else putStrLn "=== Migration Failed!"