{-# LANGUAGE TemplateHaskell #-}
{-# LANGUAGE RecordWildCards #-}
{-# LANGUAGE CPP #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE RankNTypes #-}
{-# LANGUAGE TupleSections #-}
{-# LANGUAGE FlexibleContexts, FlexibleInstances, MultiParamTypeClasses #-}
{-# LANGUAGE UndecidableInstances #-}
{-# OPTIONS_GHC -fno-warn-orphans -fno-warn-missing-fields #-}
-- overlapping instances is for automatic lifting
-- while avoiding an orphan of Lift for Text
{-# LANGUAGE OverlappingInstances #-}
-- | This module provides utilities for creating backends. Regular users do not
-- need to use this module.
module Database.Persist.TH
( -- * Parse entity defs
persistWith
, persistUpperCase
, persistLowerCase
, persistFileWith
-- * Turn @EntityDef@s into types
, mkPersist
, MkPersistSettings
, mpsBackend
, mpsGeneric
, mpsPrefixFields
, mpsEntityJSON
, mpsGenerateLenses
, EntityJSON(..)
, mkPersistSettings
, sqlSettings
, sqlOnlySettings
-- * Various other TH functions
, mkMigrate
, mkSave
, mkDeleteCascade
, share
, derivePersistField
, derivePersistFieldJSON
, persistFieldFromEntity
-- * Internal
, packPTH
, lensPTH
) where
import Prelude hiding ((++), take, concat, splitAt, exp)
import Database.Persist
import Database.Persist.Sql (Migration, migrate, SqlBackend, PersistFieldSql)
import Database.Persist.Quasi
import Language.Haskell.TH.Lib (
#if MIN_VERSION_template_haskell(2,11,0)
conT,
#endif
varE)
import Language.Haskell.TH.Quote
import Language.Haskell.TH.Syntax
import Data.Char (toLower, toUpper)
import Control.Monad (forM, (<=<), mzero)
import qualified System.IO as SIO
import Data.Text (pack, Text, append, unpack, concat, uncons, cons, stripPrefix, stripSuffix)
import Data.Text.Encoding (decodeUtf8)
import qualified Data.Text.IO as TIO
import Data.Int (Int64)
import Data.List (foldl')
import Data.Maybe (isJust, listToMaybe, mapMaybe, fromMaybe)
import Data.Monoid (mappend, mconcat)
import Text.Read (readPrec, lexP, step, prec, parens, Lexeme(Ident))
import qualified Data.Map as M
import qualified Data.HashMap.Strict as HM
import Data.Aeson.Compat
( ToJSON (toJSON), FromJSON (parseJSON), (.=), object
, Value (Object), (.:), (.:?)
, eitherDecodeStrict'
)
import Control.Applicative (pure, (<$>), (<*>))
import Database.Persist.Sql (sqlType)
import Data.Proxy (Proxy (Proxy))
import Web.PathPieces (PathPiece(..))
import Web.HttpApiData (ToHttpApiData(..), FromHttpApiData(..), parseUrlPieceMaybe)
import GHC.Generics (Generic)
import qualified Data.Text.Encoding as TE
-- | Converts a quasi-quoted syntax into a list of entity definitions, to be
-- used as input to the template haskell generation code (mkPersist).
persistWith :: PersistSettings -> QuasiQuoter
persistWith ps = QuasiQuoter
{ quoteExp = parseReferences ps . pack
}
-- | Apply 'persistWith' to 'upperCaseSettings'.
persistUpperCase :: QuasiQuoter
persistUpperCase = persistWith upperCaseSettings
-- | Apply 'persistWith' to 'lowerCaseSettings'.
persistLowerCase :: QuasiQuoter
persistLowerCase = persistWith lowerCaseSettings
-- | Same as 'persistWith', but uses an external file instead of a
-- quasiquotation.
persistFileWith :: PersistSettings -> FilePath -> Q Exp
persistFileWith ps fp = do
#ifdef GHC_7_4
qAddDependentFile fp
#endif
h <- qRunIO $ SIO.openFile fp SIO.ReadMode
qRunIO $ SIO.hSetEncoding h SIO.utf8_bom
s <- qRunIO $ TIO.hGetContents h
parseReferences ps s
-- calls parse to Quasi.parse individual entities in isolation
-- afterwards, sets references to other entities
parseReferences :: PersistSettings -> Text -> Q Exp
parseReferences ps s = lift $
map (mkEntityDefSqlTypeExp embedEntityMap entMap) noCycleEnts
where
entMap = M.fromList $ map (\ent -> (entityHaskell ent, ent)) noCycleEnts
noCycleEnts = map breakCycleEnt entsWithEmbeds
-- every EntityDef could reference each-other (as an EmbedRef)
-- let Haskell tie the knot
embedEntityMap = M.fromList $ map (\ent -> (entityHaskell ent, toEmbedEntityDef ent)) entsWithEmbeds
entsWithEmbeds = map setEmbedEntity rawEnts
setEmbedEntity ent = ent
{ entityFields = map (setEmbedField (entityHaskell ent) embedEntityMap) $ entityFields ent
}
rawEnts = parse ps s
-- self references are already broken
-- look at every emFieldEmbed to see if it refers to an already seen HaskellName
-- so start with entityHaskell ent and accumulate embeddedHaskell em
breakCycleEnt entDef =
let entName = entityHaskell entDef
in entDef { entityFields = map (breakCycleField entName) $ entityFields entDef }
breakCycleField entName f@(FieldDef { fieldReference = EmbedRef em }) =
f { fieldReference = EmbedRef $ breakCycleEmbed [entName] em }
breakCycleField _ f = f
breakCycleEmbed ancestors em =
em { embeddedFields = map (breakCycleEmField $ emName : ancestors)
(embeddedFields em)
}
where
emName = embeddedHaskell em
breakCycleEmField ancestors emf = case embeddedHaskell <$> membed of
Nothing -> emf
Just embName -> if embName `elem` ancestors
then emf { emFieldEmbed = Nothing, emFieldCycle = Just embName }
else emf { emFieldEmbed = breakCycleEmbed ancestors <$> membed }
where
membed = emFieldEmbed emf
stripId :: FieldType -> Maybe Text
stripId (FTTypeCon Nothing t) = stripSuffix "Id" t
stripId _ = Nothing
foreignReference :: FieldDef -> Maybe HaskellName
foreignReference field = case fieldReference field of
ForeignRef ref _ -> Just ref
_ -> Nothing
-- fieldSqlType at parse time can be an Exp
-- This helps delay setting fieldSqlType until lift time
data EntityDefSqlTypeExp = EntityDefSqlTypeExp EntityDef SqlTypeExp [SqlTypeExp]
deriving Show
data SqlTypeExp = SqlTypeExp FieldType
| SqlType' SqlType
deriving Show
instance Lift SqlTypeExp where
lift (SqlType' t) = lift t
lift (SqlTypeExp ftype) = return st
where
typ = ftToType ftype
mtyp = (ConT ''Proxy `AppT` typ)
typedNothing = SigE (ConE 'Proxy) mtyp
st = VarE 'sqlType `AppE` typedNothing
data FieldsSqlTypeExp = FieldsSqlTypeExp [FieldDef] [SqlTypeExp]
instance Lift FieldsSqlTypeExp where
lift (FieldsSqlTypeExp fields sqlTypeExps) =
lift $ zipWith FieldSqlTypeExp fields sqlTypeExps
data FieldSqlTypeExp = FieldSqlTypeExp FieldDef SqlTypeExp
instance Lift FieldSqlTypeExp where
lift (FieldSqlTypeExp (FieldDef{..}) sqlTypeExp) =
[|FieldDef fieldHaskell fieldDB fieldType $(lift sqlTypeExp) fieldAttrs fieldStrict fieldReference|]
instance Lift EntityDefSqlTypeExp where
lift (EntityDefSqlTypeExp ent sqlTypeExp sqlTypeExps) =
[|ent { entityFields = $(lift $ FieldsSqlTypeExp (entityFields ent) sqlTypeExps)
, entityId = $(lift $ FieldSqlTypeExp (entityId ent) sqlTypeExp)
}
|]
instance Lift ReferenceDef where
lift NoReference = [|NoReference|]
lift (ForeignRef name ft) = [|ForeignRef name ft|]
lift (EmbedRef em) = [|EmbedRef em|]
lift (CompositeRef cdef) = [|CompositeRef cdef|]
lift (SelfReference) = [|SelfReference|]
instance Lift EmbedEntityDef where
lift (EmbedEntityDef name fields) = [|EmbedEntityDef name fields|]
instance Lift EmbedFieldDef where
lift (EmbedFieldDef name em cyc) = [|EmbedFieldDef name em cyc|]
type EmbedEntityMap = M.Map HaskellName EmbedEntityDef
type EntityMap = M.Map HaskellName EntityDef
data FTTypeConDescr = FTKeyCon deriving Show
mEmbedded :: EmbedEntityMap -> FieldType -> Either (Maybe FTTypeConDescr) EmbedEntityDef
mEmbedded _ (FTTypeCon Just{} _) = Left Nothing
mEmbedded ents (FTTypeCon Nothing n) = let name = HaskellName n in
maybe (Left Nothing) Right $ M.lookup name ents
mEmbedded ents (FTList x) = mEmbedded ents x
mEmbedded ents (FTApp x y) =
-- Key converts an Record to a RecordId
-- special casing this is obviously a hack
-- This problem may not be solvable with the current QuasiQuoted approach though
if x == FTTypeCon Nothing "Key"
then Left $ Just FTKeyCon
else mEmbedded ents y
setEmbedField :: HaskellName -> EmbedEntityMap -> FieldDef -> FieldDef
setEmbedField entName allEntities field = field
{ fieldReference = case fieldReference field of
NoReference ->
case mEmbedded allEntities (fieldType field) of
Left _ -> case stripId $ fieldType field of
Nothing -> NoReference
Just name -> case M.lookup (HaskellName name) allEntities of
Nothing -> NoReference
Just x -> ForeignRef (HaskellName name)
-- This can get corrected in mkEntityDefSqlTypeExp
(FTTypeCon (Just "Data.Int") "Int64")
Right em -> if embeddedHaskell em /= entName
then EmbedRef em
else if maybeNullable field
then SelfReference
else error $ unpack $ unHaskellName entName `mappend` ": a self reference must be a Maybe"
existing@_ -> existing
}
mkEntityDefSqlTypeExp :: EmbedEntityMap -> EntityMap -> EntityDef -> EntityDefSqlTypeExp
mkEntityDefSqlTypeExp emEntities entMap ent = EntityDefSqlTypeExp ent
(getSqlType $ entityId ent)
$ (map getSqlType $ entityFields ent)
where
getSqlType field = maybe
(defaultSqlTypeExp field)
(SqlType' . SqlOther)
(listToMaybe $ mapMaybe (stripPrefix "sqltype=") $ fieldAttrs field)
-- In the case of embedding, there won't be any datatype created yet.
-- We just use SqlString, as the data will be serialized to JSON.
defaultSqlTypeExp field = case mEmbedded emEntities ftype of
Right _ -> SqlType' SqlString
Left (Just FTKeyCon) -> SqlType' SqlString
Left Nothing -> case fieldReference field of
ForeignRef refName ft -> case M.lookup refName entMap of
Nothing -> SqlTypeExp ft
-- A ForeignRef is blindly set to an Int64 in setEmbedField
-- correct that now
Just ent -> case entityPrimary ent of
Nothing -> SqlTypeExp ft
Just pdef -> case compositeFields pdef of
[] -> error "mkEntityDefSqlTypeExp: no composite fields"
[x] -> SqlTypeExp $ fieldType x
_ -> SqlType' $ SqlOther "Composite Reference"
CompositeRef _ -> SqlType' $ SqlOther "Composite Reference"
_ -> case ftype of
-- In the case of lists, we always serialize to a string
-- value (via JSON).
--
-- Normally, this would be determined automatically by
-- SqlTypeExp. However, there's one corner case: if there's
-- a list of entity IDs, the datatype for the ID has not
-- yet been created, so the compiler will fail. This extra
-- clause works around this limitation.
FTList _ -> SqlType' SqlString
_ -> SqlTypeExp ftype
where
ftype = fieldType field
-- | Create data types and appropriate 'PersistEntity' instances for the given
-- 'EntityDef's. Works well with the persist quasi-quoter.
mkPersist :: MkPersistSettings -> [EntityDef] -> Q [Dec]
mkPersist mps ents' = do
x <- fmap mconcat $ mapM (persistFieldFromEntity mps) ents
y <- fmap mconcat $ mapM (mkEntity mps) ents
z <- fmap mconcat $ mapM (mkJSON mps) ents
return $ mconcat [x, y, z]
where
ents = map fixEntityDef ents'
-- | Implement special preprocessing on EntityDef as necessary for 'mkPersist'.
-- For example, strip out any fields marked as MigrationOnly.
fixEntityDef :: EntityDef -> EntityDef
fixEntityDef ed =
ed { entityFields = filter keepField $ entityFields ed }
where
keepField fd = "MigrationOnly" `notElem` fieldAttrs fd &&
"SafeToRemove" `notElem` fieldAttrs fd
-- | Settings to be passed to the 'mkPersist' function.
data MkPersistSettings = MkPersistSettings
{ mpsBackend :: Type
-- ^ Which database backend we\'re using.
--
-- When generating data types, each type is given a generic version- which
-- works with any backend- and a type synonym for the commonly used
-- backend. This is where you specify that commonly used backend.
, mpsGeneric :: Bool
-- ^ Create generic types that can be used with multiple backends. Good for
-- reusable code, but makes error messages harder to understand. Default:
-- True.
, mpsPrefixFields :: Bool
-- ^ Prefix field names with the model name. Default: True.
, mpsEntityJSON :: Maybe EntityJSON
-- ^ Generate @ToJSON@/@FromJSON@ instances for each model types. If it's
-- @Nothing@, no instances will be generated. Default:
--
-- @
-- Just EntityJSON
-- { entityToJSON = 'keyValueEntityToJSON
-- , entityFromJSON = 'keyValueEntityFromJSON
-- }
-- @
, mpsGenerateLenses :: !Bool
-- ^ Instead of generating normal field accessors, generator lens-style accessors.
--
-- Default: False
--
-- Since 1.3.1
}
data EntityJSON = EntityJSON
{ entityToJSON :: Name
-- ^ Name of the @toJSON@ implementation for @Entity a@.
, entityFromJSON :: Name
-- ^ Name of the @fromJSON@ implementation for @Entity a@.
}
-- | Create an @MkPersistSettings@ with default values.
mkPersistSettings :: Type -- ^ Value for 'mpsBackend'
-> MkPersistSettings
mkPersistSettings t = MkPersistSettings
{ mpsBackend = t
, mpsGeneric = False
, mpsPrefixFields = True
, mpsEntityJSON = Just EntityJSON
{ entityToJSON = 'entityIdToJSON
, entityFromJSON = 'entityIdFromJSON
}
, mpsGenerateLenses = False
}
-- | Use the 'SqlPersist' backend.
sqlSettings :: MkPersistSettings
sqlSettings = mkPersistSettings $ ConT ''SqlBackend
-- | Same as 'sqlSettings'.
--
-- Since 1.1.1
sqlOnlySettings :: MkPersistSettings
sqlOnlySettings = sqlSettings
{-# DEPRECATED sqlOnlySettings "use sqlSettings" #-}
recNameNoUnderscore :: MkPersistSettings -> HaskellName -> HaskellName -> Text
recNameNoUnderscore mps dt f
| mpsPrefixFields mps = lowerFirst (unHaskellName dt) ++ upperFirst ft
| otherwise = lowerFirst ft
where ft = unHaskellName f
recName :: MkPersistSettings -> HaskellName -> HaskellName -> Text
recName mps dt f =
addUnderscore $ recNameNoUnderscore mps dt f
where
addUnderscore
| mpsGenerateLenses mps = ("_" ++)
| otherwise = id
lowerFirst :: Text -> Text
lowerFirst t =
case uncons t of
Just (a, b) -> cons (toLower a) b
Nothing -> t
upperFirst :: Text -> Text
upperFirst t =
case uncons t of
Just (a, b) -> cons (toUpper a) b
Nothing -> t
dataTypeDec :: MkPersistSettings -> EntityDef -> Q Dec
dataTypeDec mps t = do
let names = map (mkName . unpack) $ entityDerives t
#if MIN_VERSION_template_haskell(2,11,0)
DataD [] nameFinal paramsFinal
Nothing
constrs
<$> mapM conT names
#else
return $ DataD [] nameFinal paramsFinal constrs names
#endif
where
mkCol x fd@FieldDef {..} =
(mkName $ unpack $ recName mps x fieldHaskell,
if fieldStrict then isStrict else notStrict,
maybeIdType mps fd Nothing Nothing
)
(nameFinal, paramsFinal)
| mpsGeneric mps = (nameG, [PlainTV backend])
| otherwise = (name, [])
nameG = mkName $ unpack $ unHaskellName (entityHaskell t) ++ "Generic"
name = mkName $ unpack $ unHaskellName $ entityHaskell t
cols = map (mkCol $ entityHaskell t) $ entityFields t
backend = backendName
constrs
| entitySum t = map sumCon $ entityFields t
| otherwise = [RecC name cols]
sumCon fd = NormalC
(sumConstrName mps t fd)
[(notStrict, maybeIdType mps fd Nothing Nothing)]
sumConstrName :: MkPersistSettings -> EntityDef -> FieldDef -> Name
sumConstrName mps t FieldDef {..} = mkName $ unpack $ concat
[ if mpsPrefixFields mps
then unHaskellName $ entityHaskell t
else ""
, upperFirst $ unHaskellName fieldHaskell
, "Sum"
]
uniqueTypeDec :: MkPersistSettings -> EntityDef -> Dec
uniqueTypeDec mps t =
DataInstD [] ''Unique
[genericDataType mps (entityHaskell t) backendT]
#if MIN_VERSION_template_haskell(2,11,0)
Nothing
#endif
(map (mkUnique mps t) $ entityUniques t)
[]
mkUnique :: MkPersistSettings -> EntityDef -> UniqueDef -> Con
mkUnique mps t (UniqueDef (HaskellName constr) _ fields attrs) =
NormalC (mkName $ unpack constr) types
where
types = map (go . flip lookup3 (entityFields t))
$ map (unHaskellName . fst) fields
force = "!force" `elem` attrs
go :: (FieldDef, IsNullable) -> (Strict, Type)
go (_, Nullable _) | not force = error nullErrMsg
go (fd, y) = (notStrict, maybeIdType mps fd Nothing (Just y))
lookup3 :: Text -> [FieldDef] -> (FieldDef, IsNullable)
lookup3 s [] =
error $ unpack $ "Column not found: " ++ s ++ " in unique " ++ constr
lookup3 x (fd@FieldDef {..}:rest)
| x == unHaskellName fieldHaskell = (fd, nullable fieldAttrs)
| otherwise = lookup3 x rest
nullErrMsg =
mconcat [ "Error: By default we disallow NULLables in an uniqueness "
, "constraint. The semantics of how NULL interacts with those "
, "constraints is non-trivial: two NULL values are not "
, "considered equal for the purposes of an uniqueness "
, "constraint. If you understand this feature, it is possible "
, "to use it your advantage. *** Use a \"!force\" attribute "
, "on the end of the line that defines your uniqueness "
, "constraint in order to disable this check. ***" ]
maybeIdType :: MkPersistSettings
-> FieldDef
-> Maybe Name -- ^ backend
-> Maybe IsNullable
-> Type
maybeIdType mps fd mbackend mnull = maybeTyp mayNullable idtyp
where
mayNullable = case mnull of
(Just (Nullable ByMaybeAttr)) -> True
_ -> maybeNullable fd
idtyp = idType mps fd mbackend
backendDataType :: MkPersistSettings -> Type
backendDataType mps
| mpsGeneric mps = backendT
| otherwise = mpsBackend mps
genericDataType :: MkPersistSettings
-> HaskellName -- ^ entity name
-> Type -- ^ backend
-> Type
genericDataType mps (HaskellName typ') backend
| mpsGeneric mps = ConT (mkName $ unpack $ typ' ++ "Generic") `AppT` backend
| otherwise = ConT $ mkName $ unpack typ'
idType :: MkPersistSettings -> FieldDef -> Maybe Name -> Type
idType mps fd mbackend =
case foreignReference fd of
Just typ ->
ConT ''Key
`AppT` genericDataType mps typ (VarT $ fromMaybe backendName mbackend)
Nothing -> ftToType $ fieldType fd
degen :: [Clause] -> [Clause]
degen [] =
let err = VarE 'error `AppE` LitE (StringL
"Degenerate case, should never happen")
in [normalClause [WildP] err]
degen x = x
mkToPersistFields :: MkPersistSettings -> String -> EntityDef -> Q Dec
mkToPersistFields mps constr ed@EntityDef { entitySum = isSum, entityFields = fields } = do
clauses <-
if isSum
then sequence $ zipWith goSum fields [1..]
else fmap return go
return $ FunD 'toPersistFields clauses
where
go :: Q Clause
go = do
xs <- sequence $ replicate fieldCount $ newName "x"
let pat = ConP (mkName constr) $ map VarP xs
sp <- [|SomePersistField|]
let bod = ListE $ map (AppE sp . VarE) xs
return $ normalClause [pat] bod
fieldCount = length fields
goSum :: FieldDef -> Int -> Q Clause
goSum fd idx = do
let name = sumConstrName mps ed fd
enull <- [|SomePersistField PersistNull|]
let beforeCount = idx - 1
afterCount = fieldCount - idx
before = replicate beforeCount enull
after = replicate afterCount enull
x <- newName "x"
sp <- [|SomePersistField|]
let body = ListE $ mconcat
[ before
, [sp `AppE` VarE x]
, after
]
return $ normalClause [ConP name [VarP x]] body
mkToFieldNames :: [UniqueDef] -> Q Dec
mkToFieldNames pairs = do
pairs' <- mapM go pairs
return $ FunD 'persistUniqueToFieldNames $ degen pairs'
where
go (UniqueDef constr _ names _) = do
names' <- lift names
return $
normalClause
[RecP (mkName $ unpack $ unHaskellName constr) []]
names'
mkUniqueToValues :: [UniqueDef] -> Q Dec
mkUniqueToValues pairs = do
pairs' <- mapM go pairs
return $ FunD 'persistUniqueToValues $ degen pairs'
where
go :: UniqueDef -> Q Clause
go (UniqueDef constr _ names _) = do
xs <- mapM (const $ newName "x") names
let pat = ConP (mkName $ unpack $ unHaskellName constr) $ map VarP xs
tpv <- [|toPersistValue|]
let bod = ListE $ map (AppE tpv . VarE) xs
return $ normalClause [pat] bod
isNotNull :: PersistValue -> Bool
isNotNull PersistNull = False
isNotNull _ = True
mapLeft :: (a -> c) -> Either a b -> Either c b
mapLeft _ (Right r) = Right r
mapLeft f (Left l) = Left (f l)
fieldError :: Text -> Text -> Text
fieldError fieldName err = "field " `mappend` fieldName `mappend` ": " `mappend` err
mkFromPersistValues :: MkPersistSettings -> EntityDef -> Q [Clause]
mkFromPersistValues _ t@(EntityDef { entitySum = False }) =
fromValues t "fromPersistValues" entE $ entityFields t
where
entE = ConE $ mkName $ unpack entName
entName = unHaskellName $ entityHaskell t
mkFromPersistValues mps t@(EntityDef { entitySum = True }) = do
nothing <- [|Left ("Invalid fromPersistValues input: sum type with all nulls. Entity: " `mappend` entName)|]
clauses <- mkClauses [] $ entityFields t
return $ clauses `mappend` [normalClause [WildP] nothing]
where
entName = unHaskellName $ entityHaskell t
mkClauses _ [] = return []
mkClauses before (field:after) = do
x <- newName "x"
let null' = ConP 'PersistNull []
pat = ListP $ mconcat
[ map (const null') before
, [VarP x]
, map (const null') after
]
constr = ConE $ sumConstrName mps t field
fs <- [|fromPersistValue $(return $ VarE x)|]
let guard' = NormalG $ VarE 'isNotNull `AppE` VarE x
let clause = Clause [pat] (GuardedB [(guard', InfixE (Just constr) fmapE (Just fs))]) []
clauses <- mkClauses (field : before) after
return $ clause : clauses
type Lens s t a b = forall f. Functor f => (a -> f b) -> s -> f t
lensPTH :: (s -> a) -> (s -> b -> t) -> Lens s t a b
lensPTH sa sbt afb s = fmap (sbt s) (afb $ sa s)
fmapE :: Exp
fmapE = VarE 'fmap
mkLensClauses :: MkPersistSettings -> EntityDef -> Q [Clause]
mkLensClauses mps t = do
lens' <- [|lensPTH|]
getId <- [|entityKey|]
setId <- [|\(Entity _ value) key -> Entity key value|]
getVal <- [|entityVal|]
dot <- [|(.)|]
keyVar <- newName "key"
valName <- newName "value"
xName <- newName "x"
let idClause = normalClause
[ConP (keyIdName t) []]
(lens' `AppE` getId `AppE` setId)
if entitySum t
then return $ idClause : map (toSumClause lens' keyVar valName xName) (entityFields t)
else return $ idClause : map (toClause lens' getVal dot keyVar valName xName) (entityFields t)
where
toClause lens' getVal dot keyVar valName xName f = normalClause
[ConP (filterConName mps t f) []]
(lens' `AppE` getter `AppE` setter)
where
fieldName = mkName $ unpack $ recName mps (entityHaskell t) (fieldHaskell f)
getter = InfixE (Just $ VarE fieldName) dot (Just getVal)
setter = LamE
[ ConP 'Entity [VarP keyVar, VarP valName]
, VarP xName
]
$ ConE 'Entity `AppE` VarE keyVar `AppE` RecUpdE
(VarE valName)
[(fieldName, VarE xName)]
toSumClause lens' keyVar valName xName f = normalClause
[ConP (filterConName mps t f) []]
(lens' `AppE` getter `AppE` setter)
where
emptyMatch = Match WildP (NormalB $ VarE 'error `AppE` LitE (StringL "Tried to use fieldLens on a Sum type")) []
getter = LamE
[ ConP 'Entity [WildP, VarP valName]
] $ CaseE (VarE valName)
$ Match (ConP (sumConstrName mps t f) [VarP xName]) (NormalB $ VarE xName) []
-- FIXME It would be nice if the types expressed that the Field is
-- a sum type and therefore could result in Maybe.
: if length (entityFields t) > 1 then [emptyMatch] else []
setter = LamE
[ ConP 'Entity [VarP keyVar, WildP]
, VarP xName
]
$ ConE 'Entity `AppE` VarE keyVar `AppE` (ConE (sumConstrName mps t f) `AppE` VarE xName)
-- | declare the key type and associated instances
-- @'PathPiece'@, @'ToHttpApiData'@ and @'FromHttpApiData'@ instances are only generated for a Key with one field
mkKeyTypeDec :: MkPersistSettings -> EntityDef -> Q (Dec, [Dec])
mkKeyTypeDec mps t = do
(instDecs, i) <-
if mpsGeneric mps
then if not useNewtype
then do pfDec <- pfInstD
return (pfDec, [''Generic])
else do gi <- genericNewtypeInstances
return (gi, [])
else if not useNewtype
then do pfDec <- pfInstD
return (pfDec, [''Show, ''Read, ''Eq, ''Ord, ''Generic])
else do
let allInstances = [''Show, ''Read, ''Eq, ''Ord, ''PathPiece, ''ToHttpApiData, ''FromHttpApiData, ''PersistField, ''PersistFieldSql, ''ToJSON, ''FromJSON]
if customKeyType
then return ([], allInstances)
else do
bi <- backendKeyI
return (bi, allInstances)
#if MIN_VERSION_template_haskell(2,11,0)
cxti <- mapM conT i
let kd = if useNewtype
then NewtypeInstD [] k [recordType] Nothing dec cxti
else DataInstD [] k [recordType] Nothing [dec] cxti
#else
let kd = if useNewtype
then NewtypeInstD [] k [recordType] dec i
else DataInstD [] k [recordType] [dec] i
#endif
return (kd, instDecs)
where
keyConE = keyConExp t
unKeyE = unKeyExp t
dec = RecC (keyConName t) (keyFields mps t)
k = ''Key
recordType = genericDataType mps (entityHaskell t) backendT
pfInstD = -- FIXME: generate a PersistMap instead of PersistList
[d|instance PersistField (Key $(pure recordType)) where
toPersistValue = PersistList . keyToValues
fromPersistValue (PersistList l) = keyFromValues l
fromPersistValue got = error $ "fromPersistValue: expected PersistList, got: " `mappend` show got
instance PersistFieldSql (Key $(pure recordType)) where
sqlType _ = SqlString
instance ToJSON (Key $(pure recordType))
instance FromJSON (Key $(pure recordType))
|]
keyStringL = StringL . keyString
-- ghc 7.6 cannot parse the left arrow Ident $() <- lexP
keyPattern = BindS (ConP 'Ident [LitP $ keyStringL t])
backendKeyGenericI =
[d| instance PersistStore $(pure backendT) =>
ToBackendKey $(pure backendT) $(pure recordType) where
toBackendKey = $(return unKeyE)
fromBackendKey = $(return keyConE)
|]
backendKeyI = let bdt = backendDataType mps in
[d| instance ToBackendKey $(pure bdt) $(pure recordType) where
toBackendKey = $(return unKeyE)
fromBackendKey = $(return keyConE)
|]
-- truly unfortunate that TH doesn't support standalone deriving
-- https://ghc.haskell.org/trac/ghc/ticket/8100
genericNewtypeInstances = do
instances <- [|lexP|] >>= \lexPE -> [| step readPrec >>= return . ($(pure keyConE) )|] >>= \readE -> do
alwaysInstances <-
[d|instance Show (BackendKey $(pure backendT)) => Show (Key $(pure recordType)) where
showsPrec i x = showParen (i > app_prec) $
(showString $ $(pure $ LitE $ keyStringL t) `mappend` " ") .
showsPrec i ($(return unKeyE) x)
where app_prec = (10::Int)
instance Read (BackendKey $(pure backendT)) => Read (Key $(pure recordType)) where
readPrec = parens $ (prec app_prec $ $(pure $ DoE [keyPattern lexPE, NoBindS readE]))
where app_prec = (10::Int)
instance Eq (BackendKey $(pure backendT)) => Eq (Key $(pure recordType)) where
x == y =
($(return unKeyE) x) ==
($(return unKeyE) y)
instance Ord (BackendKey $(pure backendT)) => Ord (Key $(pure recordType)) where
compare x y = compare
($(return unKeyE) x)
($(return unKeyE) y)
instance ToHttpApiData (BackendKey $(pure backendT)) => ToHttpApiData (Key $(pure recordType)) where
toUrlPiece = toUrlPiece . $(return unKeyE)
instance FromHttpApiData (BackendKey $(pure backendT)) => FromHttpApiData(Key $(pure recordType)) where
parseUrlPiece = fmap $(return keyConE) . parseUrlPiece
instance PathPiece (BackendKey $(pure backendT)) => PathPiece (Key $(pure recordType)) where
toPathPiece = toPathPiece . $(return unKeyE)
fromPathPiece = fmap $(return keyConE) . fromPathPiece
instance PersistField (BackendKey $(pure backendT)) => PersistField (Key $(pure recordType)) where
toPersistValue = toPersistValue . $(return unKeyE)
fromPersistValue = fmap $(return keyConE) . fromPersistValue
instance PersistFieldSql (BackendKey $(pure backendT)) => PersistFieldSql (Key $(pure recordType)) where
sqlType = sqlType . fmap $(return unKeyE)
instance ToJSON (BackendKey $(pure backendT)) => ToJSON (Key $(pure recordType)) where
toJSON = toJSON . $(return unKeyE)
instance FromJSON (BackendKey $(pure backendT)) => FromJSON (Key $(pure recordType)) where
parseJSON = fmap $(return keyConE) . parseJSON
|]
if customKeyType then return alwaysInstances
else fmap (alwaysInstances `mappend`) backendKeyGenericI
return instances
useNewtype = pkNewtype mps t
customKeyType = not (defaultIdType t) || not useNewtype || isJust (entityPrimary t)
keyIdName :: EntityDef -> Name
keyIdName = mkName . unpack . keyIdText
keyIdText :: EntityDef -> Text
keyIdText t = (unHaskellName $ entityHaskell t) `mappend` "Id"
unKeyName :: EntityDef -> Name
unKeyName t = mkName $ "un" `mappend` keyString t
unKeyExp :: EntityDef -> Exp
unKeyExp = VarE . unKeyName
backendT :: Type
backendT = VarT backendName
backendName :: Name
backendName = mkName "backend"
keyConName :: EntityDef -> Name
keyConName t = mkName $ resolveConflict $ keyString t
where
resolveConflict kn = if conflict then kn `mappend` "'" else kn
conflict = any ((== HaskellName "key") . fieldHaskell) $ entityFields t
keyConExp :: EntityDef -> Exp
keyConExp = ConE . keyConName
keyString :: EntityDef -> String
keyString = unpack . keyText
keyText :: EntityDef -> Text
keyText t = unHaskellName (entityHaskell t) ++ "Key"
pkNewtype :: MkPersistSettings -> EntityDef -> Bool
pkNewtype mps t = length (keyFields mps t) < 2
defaultIdType :: EntityDef -> Bool
defaultIdType t = fieldType (entityId t) == FTTypeCon Nothing (keyIdText t)
keyFields :: MkPersistSettings -> EntityDef -> [(Name, Strict, Type)]
keyFields mps t = case entityPrimary t of
Just pdef -> map primaryKeyVar $ (compositeFields pdef)
Nothing -> if defaultIdType t
then [idKeyVar backendKeyType]
else [idKeyVar $ ftToType $ fieldType $ entityId t]
where
backendKeyType
| mpsGeneric mps = ConT ''BackendKey `AppT` backendT
| otherwise = ConT ''BackendKey `AppT` mpsBackend mps
idKeyVar ft = (unKeyName t, notStrict, ft)
primaryKeyVar fd = ( keyFieldName mps t fd
, notStrict
, ftToType $ fieldType fd
)
keyFieldName :: MkPersistSettings -> EntityDef -> FieldDef -> Name
keyFieldName mps t fd
| pkNewtype mps t = unKeyName t
| otherwise = mkName $ unpack
$ lowerFirst (keyText t) `mappend` (unHaskellName $ fieldHaskell fd)
mkKeyToValues :: MkPersistSettings -> EntityDef -> Q Dec
mkKeyToValues mps t = do
(p, e) <- case entityPrimary t of
Nothing ->
([],) <$> [|(:[]) . toPersistValue . $(return $ unKeyExp t)|]
Just pdef ->
return $ toValuesPrimary pdef
return $ FunD 'keyToValues $ return $ normalClause p e
where
toValuesPrimary pdef =
( [VarP recordName]
, ListE $ map (\fd -> VarE 'toPersistValue `AppE` (VarE (keyFieldName mps t fd) `AppE` VarE recordName)) $ compositeFields pdef
)
recordName = mkName "record"
normalClause :: [Pat] -> Exp -> Clause
normalClause p e = Clause p (NormalB e) []
mkKeyFromValues :: MkPersistSettings -> EntityDef -> Q Dec
mkKeyFromValues _mps t = do
clauses <- case entityPrimary t of
Nothing -> do
e <- [|fmap $(return $ keyConE) . fromPersistValue . headNote|]
return $ [normalClause [] e]
Just pdef ->
fromValues t "keyFromValues" keyConE (compositeFields pdef)
return $ FunD 'keyFromValues clauses
where
keyConE = keyConExp t
headNote :: [PersistValue] -> PersistValue
headNote (x:[]) = x
headNote xs = error $ "mkKeyFromValues: expected a list of one element, got: "
`mappend` show xs
fromValues :: EntityDef -> Text -> Exp -> [FieldDef] -> Q [Clause]
fromValues t funName conE fields = do
x <- newName "x"
let funMsg = entityText t `mappend` ": " `mappend` funName `mappend` " failed on: "
patternMatchFailure <-
[|Left $ mappend funMsg (pack $ show $(return $ VarE x))|]
suc <- patternSuccess fields
return [ suc, normalClause [VarP x] patternMatchFailure ]
where
patternSuccess [] = do
rightE <- [|Right|]
return $ normalClause [ListP []] (rightE `AppE` conE)
patternSuccess fieldsNE = do
x1 <- newName "x1"
restNames <- mapM (\i -> newName $ "x" `mappend` show i) [2..length fieldsNE]
(fpv1:mkPersistValues) <- mapM mkPvFromFd fieldsNE
app1E <- [|(<$>)|]
let conApp = infixFromPersistValue app1E fpv1 conE x1
applyE <- [|(<*>)|]
let applyFromPersistValue = infixFromPersistValue applyE
return $ normalClause
[ListP $ map VarP (x1:restNames)]
(foldl' (\exp (name, fpv) -> applyFromPersistValue fpv exp name) conApp (zip restNames mkPersistValues))
where
infixFromPersistValue applyE fpv exp name =
UInfixE exp applyE (fpv `AppE` VarE name)
mkPvFromFd = mkPersistValue . unHaskellName . fieldHaskell
mkPersistValue fieldName = [|mapLeft (fieldError fieldName) . fromPersistValue|]
mkEntity :: MkPersistSettings -> EntityDef -> Q [Dec]
mkEntity mps t = do
t' <- lift t
let nameT = unHaskellName entName
let nameS = unpack nameT
let clazz = ConT ''PersistEntity `AppT` genDataType
tpf <- mkToPersistFields mps nameS t
fpv <- mkFromPersistValues mps t
utv <- mkUniqueToValues $ entityUniques t
puk <- mkUniqueKeys t
fkc <- mapM (mkForeignKeysComposite mps t) $ entityForeigns t
let primaryField = entityId t
fields <- mapM (mkField mps t) $ primaryField : entityFields t
toFieldNames <- mkToFieldNames $ entityUniques t
(keyTypeDec, keyInstanceDecs) <- mkKeyTypeDec mps t
keyToValues' <- mkKeyToValues mps t
keyFromValues' <- mkKeyFromValues mps t
let addSyn -- FIXME maybe remove this
| mpsGeneric mps = (:) $
TySynD (mkName nameS) [] $
genericDataType mps entName $ mpsBackend mps
| otherwise = id
lensClauses <- mkLensClauses mps t
lenses <- mkLenses mps t
let instanceConstraint = if not (mpsGeneric mps) then [] else
[mkClassP ''PersistStore [backendT]]
dtd <- dataTypeDec mps t
return $ addSyn $
dtd : mconcat fkc `mappend`
([ TySynD (keyIdName t) [] $
ConT ''Key `AppT` ConT (mkName nameS)
, instanceD instanceConstraint clazz $
[ uniqueTypeDec mps t
, keyTypeDec
, keyToValues'
, keyFromValues'
, FunD 'entityDef [normalClause [WildP] t']
, tpf
, FunD 'fromPersistValues fpv
, toFieldNames
, utv
, puk
, DataInstD
[]
''EntityField
[ genDataType
, VarT $ mkName "typ"
]
#if MIN_VERSION_template_haskell(2,11,0)
Nothing
#endif
(map fst fields)
[]
, FunD 'persistFieldDef (map snd fields)
, TySynInstD
''PersistEntityBackend
#if MIN_VERSION_template_haskell(2,9,0)
(TySynEqn
[genDataType]
(backendDataType mps))
#else
[genDataType]
(backendDataType mps)
#endif
, FunD 'persistIdField [normalClause [] (ConE $ keyIdName t)]
, FunD 'fieldLens lensClauses
]
] `mappend` lenses) `mappend` keyInstanceDecs
where
genDataType = genericDataType mps entName backendT
entName = entityHaskell t
entityText :: EntityDef -> Text
entityText = unHaskellName . entityHaskell
mkLenses :: MkPersistSettings -> EntityDef -> Q [Dec]
mkLenses mps _ | not (mpsGenerateLenses mps) = return []
mkLenses _ ent | entitySum ent = return []
mkLenses mps ent = fmap mconcat $ forM (entityFields ent) $ \field -> do
let lensName' = recNameNoUnderscore mps (entityHaskell ent) (fieldHaskell field)
lensName = mkName $ unpack lensName'
fieldName = mkName $ unpack $ "_" ++ lensName'
needleN <- newName "needle"
setterN <- newName "setter"
fN <- newName "f"
aN <- newName "a"
yN <- newName "y"
let needle = VarE needleN
setter = VarE setterN
f = VarE fN
a = VarE aN
y = VarE yN
fT = mkName "f"
-- FIXME if we want to get really fancy, then: if this field is the
-- *only* Id field present, then set backend1 and backend2 to different
-- values
backend1 = backendName
backend2 = backendName
aT = maybeIdType mps field (Just backend1) Nothing
bT = maybeIdType mps field (Just backend2) Nothing
mkST backend = genericDataType mps (entityHaskell ent) (VarT backend)
sT = mkST backend1
tT = mkST backend2
t1 `arrow` t2 = ArrowT `AppT` t1 `AppT` t2
vars = PlainTV fT
: (if mpsGeneric mps then [PlainTV backend1{-, PlainTV backend2-}] else [])
return
[ SigD lensName $ ForallT vars [mkClassP ''Functor [VarT fT]] $
(aT `arrow` (VarT fT `AppT` bT)) `arrow`
(sT `arrow` (VarT fT `AppT` tT))
, FunD lensName $ return $ Clause
[VarP fN, VarP aN]
(NormalB $ fmapE
`AppE` setter
`AppE` (f `AppE` needle))
[ FunD needleN [normalClause [] (VarE fieldName `AppE` a)]
, FunD setterN $ return $ normalClause
[VarP yN]
(RecUpdE a
[ (fieldName, y)
])
]
]
mkForeignKeysComposite :: MkPersistSettings -> EntityDef -> ForeignDef -> Q [Dec]
mkForeignKeysComposite mps t ForeignDef {..} = do
let fieldName f = mkName $ unpack $ recName mps (entityHaskell t) f
let fname = fieldName foreignConstraintNameHaskell
let reftableString = unpack $ unHaskellName $ foreignRefTableHaskell
let reftableKeyName = mkName $ reftableString `mappend` "Key"
let tablename = mkName $ unpack $ entityText t
recordName <- newName "record"
let fldsE = map (\((foreignName, _),_) -> VarE (fieldName $ foreignName)
`AppE` VarE recordName) foreignFields
let mkKeyE = foldl' AppE (maybeExp foreignNullable $ ConE reftableKeyName) fldsE
let fn = FunD fname [normalClause [VarP recordName] mkKeyE]
let t2 = maybeTyp foreignNullable $ ConT ''Key `AppT` ConT (mkName reftableString)
let sig = SigD fname $ (ArrowT `AppT` (ConT tablename)) `AppT` t2
return [sig, fn]
maybeExp :: Bool -> Exp -> Exp
maybeExp may exp | may = fmapE `AppE` exp
| otherwise = exp
maybeTyp :: Bool -> Type -> Type
maybeTyp may typ | may = ConT ''Maybe `AppT` typ
| otherwise = typ
-- | produce code similar to the following:
--
-- @
-- instance PersistEntity e => PersistField e where
-- toPersistValue = PersistMap $ zip columNames (map toPersistValue . toPersistFields)
-- fromPersistValue (PersistMap o) =
-- let columns = HM.fromList o
-- in fromPersistValues $ map (\name ->
-- case HM.lookup name columns of
-- Just v -> v
-- Nothing -> PersistNull
-- fromPersistValue x = Left $ "Expected PersistMap, received: " ++ show x
-- sqlType _ = SqlString
-- @
persistFieldFromEntity :: MkPersistSettings -> EntityDef -> Q [Dec]
persistFieldFromEntity mps e = do
ss <- [|SqlString|]
obj <- [|\ent -> PersistMap $ zip (map pack columnNames) (map toPersistValue $ toPersistFields ent)|]
fpv <- [|\x -> let columns = HM.fromList x
in fromPersistValues $ map
(\(name) ->
case HM.lookup (pack name) columns of
Just v -> v
Nothing -> PersistNull)
$ columnNames
|]
compose <- [|(<=<)|]
getPersistMap' <- [|getPersistMap|]
return
[ persistFieldInstanceD (mpsGeneric mps) typ
[ FunD 'toPersistValue [ normalClause [] obj ]
, FunD 'fromPersistValue
[ normalClause [] (InfixE (Just fpv) compose $ Just getPersistMap')
]
]
, persistFieldSqlInstanceD (mpsGeneric mps) typ
[ sqlTypeFunD ss
]
]
where
typ = genericDataType mps (entityHaskell e) backendT
entFields = entityFields e
columnNames = map (unpack . unHaskellName . fieldHaskell) entFields
-- | Apply the given list of functions to the same @EntityDef@s.
--
-- This function is useful for cases such as:
--
-- >>> share [mkSave "myDefs", mkPersist sqlSettings] [persistLowerCase|...|]
share :: [[EntityDef] -> Q [Dec]] -> [EntityDef] -> Q [Dec]
share fs x = fmap mconcat $ mapM ($ x) fs
-- | Save the @EntityDef@s passed in under the given name.
mkSave :: String -> [EntityDef] -> Q [Dec]
mkSave name' defs' = do
let name = mkName name'
defs <- lift defs'
return [ SigD name $ ListT `AppT` ConT ''EntityDef
, FunD name [normalClause [] defs]
]
data Dep = Dep
{ depTarget :: HaskellName
, depSourceTable :: HaskellName
, depSourceField :: HaskellName
, depSourceNull :: IsNullable
}
-- | Generate a 'DeleteCascade' instance for the given @EntityDef@s.
mkDeleteCascade :: MkPersistSettings -> [EntityDef] -> Q [Dec]
mkDeleteCascade mps defs = do
let deps = concatMap getDeps defs
mapM (go deps) defs
where
getDeps :: EntityDef -> [Dep]
getDeps def =
concatMap getDeps' $ entityFields $ fixEntityDef def
where
getDeps' :: FieldDef -> [Dep]
getDeps' field@FieldDef {..} =
case foreignReference field of
Just name ->
return Dep
{ depTarget = name
, depSourceTable = entityHaskell def
, depSourceField = fieldHaskell
, depSourceNull = nullable fieldAttrs
}
Nothing -> []
go :: [Dep] -> EntityDef -> Q Dec
go allDeps EntityDef{entityHaskell = name} = do
let deps = filter (\x -> depTarget x == name) allDeps
key <- newName "key"
let del = VarE 'delete
let dcw = VarE 'deleteCascadeWhere
just <- [|Just|]
filt <- [|Filter|]
eq <- [|Eq|]
left <- [|Left|]
let mkStmt :: Dep -> Stmt
mkStmt dep = NoBindS
$ dcw `AppE`
ListE
[ filt `AppE` ConE filtName
`AppE` (left `AppE` val (depSourceNull dep))
`AppE` eq
]
where
filtName = filterConName' mps (depSourceTable dep) (depSourceField dep)
val (Nullable ByMaybeAttr) = just `AppE` VarE key
val _ = VarE key
let stmts :: [Stmt]
stmts = map mkStmt deps `mappend`
[NoBindS $ del `AppE` VarE key]
let entityT = genericDataType mps name backendT
return $
instanceD
[ mkClassP ''PersistQuery [backendT]
, mkEqualP (ConT ''PersistEntityBackend `AppT` entityT) backendT
]
(ConT ''DeleteCascade `AppT` entityT `AppT` backendT)
[ FunD 'deleteCascade
[normalClause [VarP key] (DoE stmts)]
]
mkUniqueKeys :: EntityDef -> Q Dec
mkUniqueKeys def | entitySum def =
return $ FunD 'persistUniqueKeys [normalClause [WildP] (ListE [])]
mkUniqueKeys def = do
c <- clause
return $ FunD 'persistUniqueKeys [c]
where
clause = do
xs <- forM (entityFields def) $ \fd -> do
let x = fieldHaskell fd
x' <- newName $ '_' : unpack (unHaskellName x)
return (x, x')
let pcs = map (go xs) $ entityUniques def
let pat = ConP
(mkName $ unpack $ unHaskellName $ entityHaskell def)
(map (VarP . snd) xs)
return $ normalClause [pat] (ListE pcs)
go :: [(HaskellName, Name)] -> UniqueDef -> Exp
go xs (UniqueDef name _ cols _) =
foldl' (go' xs) (ConE (mkName $ unpack $ unHaskellName name)) (map fst cols)
go' :: [(HaskellName, Name)] -> Exp -> HaskellName -> Exp
go' xs front col =
let Just col' = lookup col xs
in front `AppE` VarE col'
sqlTypeFunD :: Exp -> Dec
sqlTypeFunD st = FunD 'sqlType
[ normalClause [WildP] st ]
typeInstanceD :: Name
-> Bool -- ^ include PersistStore backend constraint
-> Type -> [Dec] -> Dec
typeInstanceD clazz hasBackend typ =
instanceD ctx (ConT clazz `AppT` typ)
where
ctx
| hasBackend = [mkClassP ''PersistStore [backendT]]
| otherwise = []
persistFieldInstanceD :: Bool -- ^ include PersistStore backend constraint
-> Type -> [Dec] -> Dec
persistFieldInstanceD = typeInstanceD ''PersistField
persistFieldSqlInstanceD :: Bool -- ^ include PersistStore backend constraint
-> Type -> [Dec] -> Dec
persistFieldSqlInstanceD = typeInstanceD ''PersistFieldSql
-- | Automatically creates a valid 'PersistField' instance for any datatype
-- that has valid 'Show' and 'Read' instances. Can be very convenient for
-- 'Enum' types.
derivePersistField :: String -> Q [Dec]
derivePersistField s = do
ss <- [|SqlString|]
tpv <- [|PersistText . pack . show|]
fpv <- [|\dt v ->
case fromPersistValue v of
Left e -> Left e
Right s' ->
case reads $ unpack s' of
(x, _):_ -> Right x
[] -> Left $ pack "Invalid " ++ pack dt ++ pack ": " ++ s'|]
return
[ persistFieldInstanceD False (ConT $ mkName s)
[ FunD 'toPersistValue
[ normalClause [] tpv
]
, FunD 'fromPersistValue
[ normalClause [] (fpv `AppE` LitE (StringL s))
]
]
, persistFieldSqlInstanceD False (ConT $ mkName s)
[ sqlTypeFunD ss
]
]
-- | Automatically creates a valid 'PersistField' instance for any datatype
-- that has valid 'ToJSON' and 'FromJSON' instances. For a datatype @T@ it
-- generates instances similar to these:
--
-- @
-- instance PersistField T where
-- toPersistValue = PersistByteString . L.toStrict . encode
-- fromPersistValue = (left T.pack) . eitherDecodeStrict' <=< fromPersistValue
-- instance PersistFieldSql T where
-- sqlType _ = SqlString
-- @
derivePersistFieldJSON :: String -> Q [Dec]
derivePersistFieldJSON s = do
ss <- [|SqlString|]
tpv <- [|PersistText . toJsonText|]
fpv <- [|\dt v -> do
text <- fromPersistValue v
let bs' = TE.encodeUtf8 text
case eitherDecodeStrict' bs' of
Left e -> Left $ pack "JSON decoding error for " ++ pack dt ++ pack ": " ++ pack e ++ pack ". On Input: " ++ decodeUtf8 bs'
Right x -> Right x|]
return
[ persistFieldInstanceD False (ConT $ mkName s)
[ FunD 'toPersistValue
[ normalClause [] tpv
]
, FunD 'fromPersistValue
[ normalClause [] (fpv `AppE` LitE (StringL s))
]
]
, persistFieldSqlInstanceD False (ConT $ mkName s)
[ sqlTypeFunD ss
]
]
-- | Creates a single function to perform all migrations for the entities
-- defined here. One thing to be aware of is dependencies: if you have entities
-- with foreign references, make sure to place those definitions after the
-- entities they reference.
mkMigrate :: String -> [EntityDef] -> Q [Dec]
mkMigrate fun allDefs = do
body' <- body
return
[ SigD (mkName fun) typ
, FunD (mkName fun) [normalClause [] body']
]
where
defs = filter isMigrated allDefs
isMigrated def = not $ "no-migrate" `elem` entityAttrs def
typ = ConT ''Migration
body :: Q Exp
body =
case defs of
[] -> [|return ()|]
_ -> do
defsName <- newName "defs"
defsStmt <- do
defs' <- mapM lift defs
let defsExp = ListE defs'
return $ LetS [ValD (VarP defsName) (NormalB defsExp) []]
stmts <- mapM (toStmt $ VarE defsName) defs
return (DoE $ defsStmt : stmts)
toStmt :: Exp -> EntityDef -> Q Stmt
toStmt defsExp ed = do
u <- lift ed
m <- [|migrate|]
return $ NoBindS $ m `AppE` defsExp `AppE` u
instance Lift EntityDef where
lift EntityDef{..} =
[|EntityDef
entityHaskell
entityDB
entityId
entityAttrs
entityFields
entityUniques
entityForeigns
entityDerives
entityExtra
entitySum
|]
instance Lift FieldDef where
lift (FieldDef a b c d e f g) = [|FieldDef a b c d e f g|]
instance Lift UniqueDef where
lift (UniqueDef a b c d) = [|UniqueDef a b c d|]
instance Lift CompositeDef where
lift (CompositeDef a b) = [|CompositeDef a b|]
instance Lift ForeignDef where
lift (ForeignDef a b c d e f g) = [|ForeignDef a b c d e f g|]
-- | A hack to avoid orphans.
class Lift' a where
lift' :: a -> Q Exp
instance Lift' Text where
lift' = liftT
instance Lift' a => Lift' [a] where
lift' xs = do { xs' <- mapM lift' xs; return (ListE xs') }
instance (Lift' k, Lift' v) => Lift' (M.Map k v) where
lift' m = [|M.fromList $(fmap ListE $ mapM liftPair $ M.toList m)|]
-- auto-lifting, means instances are overlapping
instance Lift' a => Lift a where
lift = lift'
packPTH :: String -> Text
packPTH = pack
#if !MIN_VERSION_text(0, 11, 2)
{-# NOINLINE packPTH #-}
#endif
liftT :: Text -> Q Exp
liftT t = [|packPTH $(lift (unpack t))|]
liftPair :: (Lift' k, Lift' v) => (k, v) -> Q Exp
liftPair (k, v) = [|($(lift' k), $(lift' v))|]
instance Lift HaskellName where
lift (HaskellName t) = [|HaskellName t|]
instance Lift DBName where
lift (DBName t) = [|DBName t|]
instance Lift FieldType where
lift (FTTypeCon Nothing t) = [|FTTypeCon Nothing t|]
lift (FTTypeCon (Just x) t) = [|FTTypeCon (Just x) t|]
lift (FTApp x y) = [|FTApp x y|]
lift (FTList x) = [|FTList x|]
instance Lift PersistFilter where
lift Eq = [|Eq|]
lift Ne = [|Ne|]
lift Gt = [|Gt|]
lift Lt = [|Lt|]
lift Ge = [|Ge|]
lift Le = [|Le|]
lift In = [|In|]
lift NotIn = [|NotIn|]
lift (BackendSpecificFilter x) = [|BackendSpecificFilter x|]
instance Lift PersistUpdate where
lift Assign = [|Assign|]
lift Add = [|Add|]
lift Subtract = [|Subtract|]
lift Multiply = [|Multiply|]
lift Divide = [|Divide|]
lift (BackendSpecificUpdate x) = [|BackendSpecificUpdate x|]
instance Lift SqlType where
lift SqlString = [|SqlString|]
lift SqlInt32 = [|SqlInt32|]
lift SqlInt64 = [|SqlInt64|]
lift SqlReal = [|SqlReal|]
lift (SqlNumeric x y) =
[|SqlNumeric (fromInteger x') (fromInteger y')|]
where
x' = fromIntegral x :: Integer
y' = fromIntegral y :: Integer
lift SqlBool = [|SqlBool|]
lift SqlDay = [|SqlDay|]
lift SqlTime = [|SqlTime|]
lift SqlDayTime = [|SqlDayTime|]
lift SqlBlob = [|SqlBlob|]
lift (SqlOther a) = [|SqlOther a|]
-- Ent
-- fieldName FieldType
--
-- forall . typ ~ FieldType => EntFieldName
--
-- EntFieldName = FieldDef ....
mkField :: MkPersistSettings -> EntityDef -> FieldDef -> Q (Con, Clause)
mkField mps et cd = do
let con = ForallC
[]
[mkEqualP (VarT $ mkName "typ") $ maybeIdType mps cd Nothing Nothing]
$ NormalC name []
bod <- lift cd
let cla = normalClause
[ConP name []]
bod
return (con, cla)
where
name = filterConName mps et cd
maybeNullable :: FieldDef -> Bool
maybeNullable fd = nullable (fieldAttrs fd) == Nullable ByMaybeAttr
filterConName :: MkPersistSettings
-> EntityDef
-> FieldDef
-> Name
filterConName mps entity field = filterConName' mps (entityHaskell entity) (fieldHaskell field)
filterConName' :: MkPersistSettings
-> HaskellName -- ^ table
-> HaskellName -- ^ field
-> Name
filterConName' mps entity field = mkName $ unpack $ concat
[ if mpsPrefixFields mps || field == HaskellName "Id"
then unHaskellName entity
else ""
, upperFirst $ unHaskellName field
]
ftToType :: FieldType -> Type
ftToType (FTTypeCon Nothing t) = ConT $ mkName $ unpack t
-- This type is generated from the Quasi-Quoter.
-- Adding this special case avoids users needing to import Data.Int
ftToType (FTTypeCon (Just "Data.Int") "Int64") = ConT ''Int64
ftToType (FTTypeCon (Just m) t) = ConT $ mkName $ unpack $ concat [m, ".", t]
ftToType (FTApp x y) = ftToType x `AppT` ftToType y
ftToType (FTList x) = ListT `AppT` ftToType x
infixr 5 ++
(++) :: Text -> Text -> Text
(++) = append
mkJSON :: MkPersistSettings -> EntityDef -> Q [Dec]
mkJSON _ def | not ("json" `elem` entityAttrs def) = return []
mkJSON mps def = do
pureE <- [|pure|]
apE' <- [|(<*>)|]
packE <- [|pack|]
dotEqualE <- [|(.=)|]
dotColonE <- [|(.:)|]
dotColonQE <- [|(.:?)|]
objectE <- [|object|]
obj <- newName "obj"
mzeroE <- [|mzero|]
xs <- mapM (newName . unpack . unHaskellName . fieldHaskell)
$ entityFields def
let conName = mkName $ unpack $ unHaskellName $ entityHaskell def
typ = genericDataType mps (entityHaskell def) backendT
toJSONI = typeInstanceD ''ToJSON (mpsGeneric mps) typ [toJSON']
toJSON' = FunD 'toJSON $ return $ normalClause
[ConP conName $ map VarP xs]
(objectE `AppE` ListE pairs)
pairs = zipWith toPair (entityFields def) xs
toPair f x = InfixE
(Just (packE `AppE` LitE (StringL $ unpack $ unHaskellName $ fieldHaskell f)))
dotEqualE
(Just $ VarE x)
fromJSONI = typeInstanceD ''FromJSON (mpsGeneric mps) typ [parseJSON']
parseJSON' = FunD 'parseJSON
[ normalClause [ConP 'Object [VarP obj]]
(foldl'
(\x y -> InfixE (Just x) apE' (Just y))
(pureE `AppE` ConE conName)
pulls
)
, normalClause [WildP] mzeroE
]
pulls = map toPull $ entityFields def
toPull f = InfixE
(Just $ VarE obj)
(if maybeNullable f then dotColonQE else dotColonE)
(Just $ AppE packE $ LitE $ StringL $ unpack $ unHaskellName $ fieldHaskell f)
case mpsEntityJSON mps of
Nothing -> return [toJSONI, fromJSONI]
Just entityJSON -> do
entityJSONIs <- if mpsGeneric mps
then [d|
#if MIN_VERSION_base(4, 6, 0)
instance PersistStore backend => ToJSON (Entity $(pure typ)) where
toJSON = $(varE (entityToJSON entityJSON))
instance PersistStore backend => FromJSON (Entity $(pure typ)) where
parseJSON = $(varE (entityFromJSON entityJSON))
#endif
|]
else [d|
instance ToJSON (Entity $(pure typ)) where
toJSON = $(varE (entityToJSON entityJSON))
instance FromJSON (Entity $(pure typ)) where
parseJSON = $(varE (entityFromJSON entityJSON))
|]
return $ toJSONI : fromJSONI : entityJSONIs
mkClassP :: Name -> [Type] -> Pred
#if MIN_VERSION_template_haskell(2,10,0)
mkClassP cla tys = foldl AppT (ConT cla) tys
#else
mkClassP = ClassP
#endif
mkEqualP :: Type -> Type -> Pred
#if MIN_VERSION_template_haskell(2,10,0)
mkEqualP tleft tright = foldl AppT EqualityT [tleft, tright]
#else
mkEqualP = EqualP
#endif
#if MIN_VERSION_template_haskell(2,11,0)
notStrict :: Bang
notStrict = Bang NoSourceUnpackedness NoSourceStrictness
isStrict :: Bang
isStrict = Bang NoSourceUnpackedness SourceStrict
#else
notStrict :: Strict
notStrict = NotStrict
isStrict :: Strict
isStrict = IsStrict
#endif
instanceD :: Cxt -> Type -> [Dec] -> Dec
#if MIN_VERSION_template_haskell(2,11,0)
instanceD = InstanceD Nothing
#else
instanceD = InstanceD
#endif
-- entityUpdates :: EntityDef -> [(HaskellName, FieldType, IsNullable, PersistUpdate)]
-- entityUpdates =
-- concatMap go . entityFields
-- where
-- go FieldDef {..} = map (\a -> (fieldHaskell, fieldType, nullable fieldAttrs, a)) [minBound..maxBound]
-- mkToUpdate :: String -> [(String, PersistUpdate)] -> Q Dec
-- mkToUpdate name pairs = do
-- pairs' <- mapM go pairs
-- return $ FunD (mkName name) $ degen pairs'
-- where
-- go (constr, pu) = do
-- pu' <- lift pu
-- return $ normalClause [RecP (mkName constr) []] pu'
-- mkToFieldName :: String -> [(String, String)] -> Dec
-- mkToFieldName func pairs =
-- FunD (mkName func) $ degen $ map go pairs
-- where
-- go (constr, name) =
-- normalClause [RecP (mkName constr) []] (LitE $ StringL name)
-- mkToValue :: String -> [String] -> Dec
-- mkToValue func = FunD (mkName func) . degen . map go
-- where
-- go constr =
-- let x = mkName "x"
-- in normalClause [ConP (mkName constr) [VarP x]]
-- (VarE 'toPersistValue `AppE` VarE x)