persistent-mysql-0.8.1: Database/Persist/MySQL.hs
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE FlexibleContexts #-}
-- | A MySQL backend for @persistent@.
module Database.Persist.MySQL
( withMySQLPool
, withMySQLConn
, createMySQLPool
, module Database.Persist
, module Database.Persist.GenericSql
, MySQL.ConnectInfo(..)
, MySQLBase.SSLInfo(..)
, MySQL.defaultConnectInfo
, MySQLBase.defaultSSLInfo
, MySQLConf(..)
) where
import Control.Arrow
import Control.Monad (mzero)
import Control.Monad.IO.Class (MonadIO (..))
import Control.Monad.Trans.Class (lift)
import Control.Monad.Trans.Error (ErrorT(..))
import Data.Aeson
import Data.ByteString (ByteString)
import Data.Either (partitionEithers)
import Data.Function (on)
import Data.IORef
import Data.List (find, intercalate, sort, groupBy)
import Data.Text (Text, pack)
-- import Data.Time.LocalTime (localTimeToUTC, utc)
import System.Environment (getEnvironment)
import qualified Data.Conduit as C
import qualified Data.Conduit.List as CL
import qualified Data.Map as Map
import qualified Data.Text as T
import qualified Data.Text.Encoding as T
import Database.Persist hiding (Entity (..))
import Database.Persist.Store
import Database.Persist.GenericSql hiding (Key(..))
import Database.Persist.GenericSql.Internal
import Database.Persist.EntityDef
import qualified Database.MySQL.Simple as MySQL
import qualified Database.MySQL.Simple.Param as MySQL
import qualified Database.MySQL.Simple.Result as MySQL
import qualified Database.MySQL.Simple.Types as MySQL
import qualified Database.MySQL.Base as MySQLBase
import qualified Database.MySQL.Base.Types as MySQLBase
-- | Create a MySQL connection pool and run the given action.
-- The pool is properly released after the action finishes using
-- it. Note that you should not use the given 'ConnectionPool'
-- outside the action since it may be already been released.
withMySQLPool :: MonadIO m =>
MySQL.ConnectInfo
-- ^ Connection information.
-> Int
-- ^ Number of connections to be kept open in the pool.
-> (ConnectionPool -> m a)
-- ^ Action to be executed that uses the connection pool.
-> m a
withMySQLPool ci = withSqlPool $ open' ci
-- | Create a MySQL connection pool. Note that it's your
-- responsability to properly close the connection pool when
-- unneeded. Use 'withMySQLPool' for automatic resource control.
createMySQLPool :: MonadIO m =>
MySQL.ConnectInfo
-- ^ Connection information.
-> Int
-- ^ Number of connections to be kept open in the pool.
-> m ConnectionPool
createMySQLPool ci = createSqlPool $ open' ci
-- | Same as 'withMySQLPool', but instead of opening a pool
-- of connections, only one connection is opened.
withMySQLConn :: C.ResourceIO m =>
MySQL.ConnectInfo
-- ^ Connection information.
-> (Connection -> m a)
-- ^ Action to be executed that uses the connection.
-> m a
withMySQLConn = withSqlConn . open'
-- | Internal function that opens a connection to the MySQL
-- server.
open' :: MySQL.ConnectInfo -> IO Connection
open' ci = do
conn <- MySQL.connect ci
MySQLBase.autocommit conn False -- disable autocommit!
smap <- newIORef $ Map.empty
return Connection
{ prepare = prepare' conn
, stmtMap = smap
, insertSql = insertSql'
, close = MySQL.close conn
, migrateSql = migrate' ci
, begin = const $ MySQL.execute_ conn "start transaction" >> return ()
, commitC = const $ MySQL.commit conn
, rollbackC = const $ MySQL.rollback conn
, escapeName = pack . escapeDBName
, noLimit = "LIMIT 18446744073709551615"
-- This noLimit is suggested by MySQL's own docs, see
-- <http://dev.mysql.com/doc/refman/5.5/en/select.html>
}
-- | Prepare a query. We don't support prepared statements, but
-- we'll do some client-side preprocessing here.
prepare' :: MySQL.Connection -> Text -> IO Statement
prepare' conn sql = do
let query = MySQL.Query (T.encodeUtf8 sql)
return Statement
{ finalize = return ()
, reset = return ()
, execute = execute' conn query
, withStmt = withStmt' conn query
}
-- | SQL code to be executed when inserting an entity.
insertSql' :: DBName -> [DBName] -> Either Text (Text, Text)
insertSql' t cols = Right (doInsert, "SELECT LAST_INSERT_ID()")
where
doInsert = pack $ concat
[ "INSERT INTO "
, escapeDBName t
, "("
, intercalate "," $ map escapeDBName cols
, ") VALUES("
, intercalate "," (map (const "?") cols)
, ")"
]
-- | Execute an statement that doesn't return any results.
execute' :: MySQL.Connection -> MySQL.Query -> [PersistValue] -> IO ()
execute' conn query vals = MySQL.execute conn query (map P vals) >> return ()
-- | Execute an statement that does return results. The results
-- are fetched all at once and stored into memory.
withStmt' :: C.ResourceIO m
=> MySQL.Connection
-> MySQL.Query
-> [PersistValue]
-> C.Source m [PersistValue]
withStmt' conn query vals = C.sourceIO (liftIO openS )
(liftIO . closeS)
(liftIO . pullS )
where
openS = do
-- Execute the query
MySQLBase.query conn =<< MySQL.formatQuery conn query (map P vals)
result <- MySQLBase.storeResult conn
-- Find out the type of the columns
fields <- MySQLBase.fetchFields result
let getters = [ maybe PersistNull (getGetter (MySQLBase.fieldType f) f . Just) | f <- fields]
-- Ready to go!
return (result, getters)
closeS (result, _) = MySQLBase.freeResult result
pullS (result, getters) = do
row <- MySQLBase.fetchRow result
case row of
[] -> MySQLBase.freeResult result >> return C.IOClosed
_ -> return $ C.IOOpen $ zipWith ($) getters row
-- | @newtype@ around 'PersistValue' that supports the
-- 'MySQL.Param' type class.
newtype P = P PersistValue
instance MySQL.Param P where
render (P (PersistText t)) = MySQL.render t
render (P (PersistByteString bs)) = MySQL.render bs
render (P (PersistInt64 i)) = MySQL.render i
render (P (PersistDouble d)) = MySQL.render d
render (P (PersistBool b)) = MySQL.render b
render (P (PersistDay d)) = MySQL.render d
render (P (PersistTimeOfDay t)) = MySQL.render t
render (P (PersistUTCTime t)) = MySQL.render t
render (P PersistNull) = MySQL.render MySQL.Null
render (P (PersistList l)) = MySQL.render $ listToJSON l
render (P (PersistMap m)) = MySQL.render $ mapToJSON m
render (P (PersistObjectId _)) =
error "Refusing to serialize a PersistObjectId to a MySQL value"
-- | @Getter a@ is a function that converts an incoming value
-- into a data type @a@.
type Getter a = MySQLBase.Field -> Maybe ByteString -> a
-- | Helper to construct 'Getter'@s@ using 'MySQL.Result'.
convertPV :: MySQL.Result a => (a -> b) -> Getter b
convertPV f = (f .) . MySQL.convert
-- | Get the corresponding @'Getter' 'PersistValue'@ depending on
-- the type of the column.
getGetter :: MySQLBase.Type -> Getter PersistValue
-- Bool
getGetter MySQLBase.Tiny = convertPV PersistBool
-- Int64
getGetter MySQLBase.Int24 = convertPV PersistInt64
getGetter MySQLBase.Short = convertPV PersistInt64
getGetter MySQLBase.Long = convertPV PersistInt64
getGetter MySQLBase.LongLong = convertPV PersistInt64
-- Double
getGetter MySQLBase.Float = convertPV PersistDouble
getGetter MySQLBase.Double = convertPV PersistDouble
getGetter MySQLBase.Decimal = convertPV PersistDouble
getGetter MySQLBase.NewDecimal = convertPV PersistDouble
-- Text
getGetter MySQLBase.VarChar = convertPV persistText
getGetter MySQLBase.VarString = convertPV persistText
getGetter MySQLBase.String = convertPV persistText
-- ByteString
getGetter MySQLBase.Blob = convertPV PersistByteString
getGetter MySQLBase.TinyBlob = convertPV PersistByteString
getGetter MySQLBase.MediumBlob = convertPV PersistByteString
getGetter MySQLBase.LongBlob = convertPV PersistByteString
-- Time-related
getGetter MySQLBase.Time = convertPV PersistTimeOfDay
getGetter MySQLBase.DateTime = convertPV PersistUTCTime
getGetter MySQLBase.Timestamp = convertPV PersistUTCTime
getGetter MySQLBase.Date = convertPV PersistDay
getGetter MySQLBase.NewDate = convertPV PersistDay
getGetter MySQLBase.Year = convertPV PersistDay
-- Null
getGetter MySQLBase.Null = \_ _ -> PersistNull
-- Controversial conversions
getGetter MySQLBase.Set = convertPV PersistText
getGetter MySQLBase.Enum = convertPV PersistText
-- Unsupported
getGetter other = error $ "MySQL.getGetter: type " ++
show other ++ " not supported."
persistText :: ByteString -> PersistValue
persistText = PersistText . T.decodeUtf8
----------------------------------------------------------------------
-- | Create the migration plan for the given 'PersistEntity'
-- @val@.
migrate' :: PersistEntity val
=> MySQL.ConnectInfo
-> [EntityDef]
-> (Text -> IO Statement)
-> val
-> IO (Either [Text] [(Bool, Text)])
migrate' connectInfo allDefs getter val = do
let name = entityDB $ entityDef val
old <- getColumns connectInfo getter $ entityDef val
let new = second (map udToPair) $ mkColumns allDefs val
case (old, partitionEithers old) of
-- Nothing found, create everything
([], _) -> do
let addTable = AddTable $ concat
[ "CREATE TABLE "
, escapeDBName name
, "("
, escapeDBName $ entityID $ entityDef val
, " BIGINT NOT NULL AUTO_INCREMENT PRIMARY KEY"
, concatMap (\x -> ',' : showColumn x) $ fst new
, ")"
]
let uniques = flip concatMap (snd new) $ \(uname, ucols) ->
[ AlterTable name $
AddUniqueConstraint uname $
map (findTypeOfColumn allDefs name) ucols ]
let foreigns = do
Column cname _ _ _ _ (Just (refTblName, _)) <- fst new
return $ AlterColumn name (cname, addReference allDefs refTblName)
return $ Right $ map showAlterDb $ addTable : uniques ++ foreigns
-- No errors and something found, migrate
(_, ([], old')) -> do
let (acs, ats) = getAlters allDefs name new $ partitionEithers old'
acs' = map (AlterColumn name) acs
ats' = map (AlterTable name) ats
return $ Right $ map showAlterDb $ acs' ++ ats'
-- Errors
(_, (errs, _)) -> return $ Left errs
-- | Find out the type of a column.
findTypeOfColumn :: [EntityDef] -> DBName -> DBName -> (DBName, FieldType)
findTypeOfColumn allDefs name col =
maybe (error $ "Could not find type of column " ++
show col ++ " on table " ++ show name ++
" (allDefs = " ++ show allDefs ++ ")")
((,) col) $ do
entDef <- find ((== name) . entityDB) allDefs
fieldDef <- find ((== col) . fieldDB) (entityFields entDef)
return (fieldType fieldDef)
-- | Helper for 'AddRefence' that finds out the 'entityID'.
addReference :: [EntityDef] -> DBName -> AlterColumn
addReference allDefs name = AddReference name id_
where
id_ = maybe (error $ "Could not find ID of entity " ++ show name
++ " (allDefs = " ++ show allDefs ++ ")")
id $ do
entDef <- find ((== name) . entityDB) allDefs
return (entityID entDef)
data AlterColumn = Change Column
| Add Column
| Drop
| Default String
| NoDefault
| Update String
| AddReference DBName DBName
| DropReference DBName
type AlterColumn' = (DBName, AlterColumn)
data AlterTable = AddUniqueConstraint DBName [(DBName, FieldType)]
| DropUniqueConstraint DBName
data AlterDB = AddTable String
| AlterColumn DBName AlterColumn'
| AlterTable DBName AlterTable
udToPair :: UniqueDef -> (DBName, [DBName])
udToPair ud = (uniqueDBName ud, map snd $ uniqueFields ud)
----------------------------------------------------------------------
-- | Returns all of the 'Column'@s@ in the given table currently
-- in the database.
getColumns :: MySQL.ConnectInfo
-> (Text -> IO Statement)
-> EntityDef
-> IO [Either Text (Either Column (DBName, [DBName]))]
getColumns connectInfo getter def = do
-- Find out all columns.
stmtClmns <- getter "SELECT COLUMN_NAME, \
\IS_NULLABLE, \
\DATA_TYPE, \
\COLUMN_DEFAULT \
\FROM INFORMATION_SCHEMA.COLUMNS \
\WHERE TABLE_SCHEMA = ? \
\AND TABLE_NAME = ? \
\AND COLUMN_NAME <> ?"
inter <- C.runResourceT $ withStmt stmtClmns vals C.$$ CL.consume
cs <- C.runResourceT $ CL.sourceList inter C.$$ helperClmns -- avoid nested queries
-- Find out the constraints.
stmtCntrs <- getter "SELECT CONSTRAINT_NAME, \
\COLUMN_NAME \
\FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE \
\WHERE TABLE_SCHEMA = ? \
\AND TABLE_NAME = ? \
\AND COLUMN_NAME <> ? \
\AND REFERENCED_TABLE_SCHEMA IS NULL \
\ORDER BY CONSTRAINT_NAME, \
\COLUMN_NAME"
us <- C.runResourceT $ withStmt stmtCntrs vals C.$$ helperCntrs
-- Return both
return $ cs ++ us
where
vals = [ PersistText $ pack $ MySQL.connectDatabase connectInfo
, PersistText $ unDBName $ entityDB def
, PersistText $ unDBName $ entityID def ]
helperClmns = CL.mapM getIt C.=$ CL.consume
where
getIt = fmap (either Left (Right . Left)) .
liftIO .
getColumn connectInfo getter (entityDB def)
helperCntrs = do
let check [PersistText cntrName, PersistText clmnName] = return (cntrName, clmnName)
check other = fail $ "helperCntrs: unexpected " ++ show other
rows <- mapM check =<< CL.consume
return $ map (Right . Right . (DBName . fst . head &&& map (DBName . snd)))
$ groupBy ((==) `on` fst) rows
-- | Get the information about a column in a table.
getColumn :: MySQL.ConnectInfo
-> (Text -> IO Statement)
-> DBName
-> [PersistValue]
-> IO (Either Text Column)
getColumn connectInfo getter tname [ PersistText cname
, PersistText null_
, PersistText type'
, default'] =
fmap (either (Left . pack) Right) $
runErrorT $ do
-- Default value
default_ <- case default' of
PersistNull -> return Nothing
PersistText t -> return (Just t)
_ -> fail $ "Invalid default column: " ++ show default'
-- Column type
type_ <- parseType type'
-- Foreign key (if any)
stmt <- lift $ getter "SELECT REFERENCED_TABLE_NAME, \
\CONSTRAINT_NAME \
\FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE \
\WHERE TABLE_SCHEMA = ? \
\AND TABLE_NAME = ? \
\AND COLUMN_NAME = ? \
\AND REFERENCED_TABLE_SCHEMA = ? \
\ORDER BY CONSTRAINT_NAME, \
\COLUMN_NAME"
let vars = [ PersistText $ pack $ MySQL.connectDatabase connectInfo
, PersistText $ unDBName $ tname
, PersistText $ cname
, PersistText $ pack $ MySQL.connectDatabase connectInfo ]
cntrs <- C.runResourceT $ withStmt stmt vars C.$$ CL.consume
ref <- case cntrs of
[] -> return Nothing
[[PersistText tab, PersistText ref]] ->
return $ Just (DBName tab, DBName ref)
_ -> fail "MySQL.getColumn/getRef: never here"
-- Okay!
return $ Column (DBName cname) (null_ == "YES") type_ default_ Nothing ref -- FIXME: maxLen
getColumn _ _ _ x =
return $ Left $ pack $ "Invalid result from INFORMATION_SCHEMA: " ++ show x
-- | Parse the type of column as returned by MySQL's
-- @INFORMATION_SCHEMA@ tables.
parseType :: Monad m => Text -> m SqlType
parseType "tinyint" = return SqlBool
-- Ints
parseType "int" = return SqlInt32
parseType "short" = return SqlInt32
parseType "long" = return SqlInteger
parseType "longlong" = return SqlInteger
parseType "mediumint" = return SqlInt32
parseType "bigint" = return SqlInteger
-- Double
parseType "float" = return SqlReal
parseType "double" = return SqlReal
parseType "decimal" = return SqlReal
parseType "newdecimal" = return SqlReal
-- Text
parseType "varchar" = return SqlString
parseType "varstring" = return SqlString
parseType "string" = return SqlString
parseType "text" = return SqlString
parseType "tinytext" = return SqlString
parseType "mediumtext" = return SqlString
parseType "longtext" = return SqlString
-- ByteString
parseType "varbinary" = return SqlBlob
parseType "blob" = return SqlBlob
parseType "tinyblob" = return SqlBlob
parseType "mediumblob" = return SqlBlob
parseType "longblob" = return SqlBlob
-- Time-related
parseType "time" = return SqlTime
parseType "datetime" = return SqlDayTime
parseType "timestamp" = return SqlDayTime
parseType "date" = return SqlDay
parseType "newdate" = return SqlDay
parseType "year" = return SqlDay
-- Unsupported
parseType other = fail $ "MySQL.parseType: type " ++
show other ++ " not supported."
----------------------------------------------------------------------
-- | @getAlters allDefs tblName new old@ finds out what needs to
-- be changed from @old@ to become @new@.
getAlters :: [EntityDef]
-> DBName
-> ([Column], [(DBName, [DBName])])
-> ([Column], [(DBName, [DBName])])
-> ([AlterColumn'], [AlterTable])
getAlters allDefs tblName (c1, u1) (c2, u2) =
(getAltersC c1 c2, getAltersU u1 u2)
where
getAltersC [] old = map (\x -> (cName x, Drop)) old
getAltersC (new:news) old =
let (alters, old') = findAlters allDefs new old
in alters ++ getAltersC news old'
getAltersU [] old = map (DropUniqueConstraint . fst) old
getAltersU ((name, cols):news) old =
case lookup name old of
Nothing ->
AddUniqueConstraint name (map findType cols) : getAltersU news old
Just ocols ->
let old' = filter (\(x, _) -> x /= name) old
in if sort cols == ocols
then getAltersU news old'
else DropUniqueConstraint name
: AddUniqueConstraint name (map findType cols)
: getAltersU news old'
where
findType = findTypeOfColumn allDefs tblName
-- | @findAlters newColumn oldColumns@ finds out what needs to be
-- changed in the columns @oldColumns@ for @newColumn@ to be
-- supported.
findAlters :: [EntityDef] -> Column -> [Column] -> ([AlterColumn'], [Column])
findAlters allDefs col@(Column name isNull type_ def _maxLen ref) cols =
case filter ((name ==) . cName) cols of
[] -> ( let cnstr = [addReference allDefs tname | Just (tname, _) <- [ref]]
in map ((,) name) (Add col : cnstr)
, cols )
Column _ isNull' type_' def' _maxLen' ref':_ ->
let -- Foreign key
refDrop = case (ref == ref', ref') of
(False, Just (_, cname)) -> [(name, DropReference cname)]
_ -> []
refAdd = case (ref == ref', ref) of
(False, Just (tname, _)) -> [(name, addReference allDefs tname)]
_ -> []
-- Type and nullability
modType | type_ == type_' && isNull == isNull' = []
| otherwise = [(name, Change col)]
-- Default value
modDef | def == def' = []
| otherwise = case def of
Nothing -> [(name, NoDefault)]
Just s -> [(name, Default $ T.unpack s)]
in ( refDrop ++ modType ++ modDef ++ refAdd
, filter ((name /=) . cName) cols )
----------------------------------------------------------------------
-- | Prints the part of a @CREATE TABLE@ statement about a given
-- column.
showColumn :: Column -> String
showColumn (Column n nu t def maxLen ref) = concat
[ escapeDBName n
, " "
, showSqlType t maxLen
, " "
, if nu then "NULL" else "NOT NULL"
, case def of
Nothing -> ""
Just s -> " DEFAULT " ++ T.unpack s
, case ref of
Nothing -> ""
Just (s, _) -> " REFERENCES " ++ escapeDBName s
]
-- | Renders an 'SqlType' in MySQL's format.
showSqlType :: SqlType
-> Maybe Integer -- ^ @maxlen@
-> String
showSqlType SqlBlob Nothing = "BLOB"
showSqlType SqlBlob (Just i) = "VARBINARY(" ++ show i ++ ")"
showSqlType SqlBool _ = "TINYINT(1)"
showSqlType SqlDay _ = "DATE"
showSqlType SqlDayTime _ = "DATETIME"
showSqlType SqlInt32 _ = "INT"
showSqlType SqlInteger _ = "BIGINT"
showSqlType SqlReal _ = "DOUBLE PRECISION"
showSqlType SqlString Nothing = "TEXT CHARACTER SET utf8"
showSqlType SqlString (Just i) = "VARCHAR(" ++ show i ++ ") CHARACTER SET utf8"
showSqlType SqlTime _ = "TIME"
-- | Render an action that must be done on the database.
showAlterDb :: AlterDB -> (Bool, Text)
showAlterDb (AddTable s) = (False, pack s)
showAlterDb (AlterColumn t (c, ac)) =
(isUnsafe ac, pack $ showAlter t (c, ac))
where
isUnsafe Drop = True
isUnsafe _ = False
showAlterDb (AlterTable t at) = (False, pack $ showAlterTable t at)
-- | Render an action that must be done on a table.
showAlterTable :: DBName -> AlterTable -> String
showAlterTable table (AddUniqueConstraint cname cols) = concat
[ "ALTER TABLE "
, escapeDBName table
, " ADD CONSTRAINT "
, escapeDBName cname
, " UNIQUE("
, intercalate "," $ map escapeDBName' cols
, ")"
]
where
escapeDBName' (name, (FTTypeCon _ "Text" )) = escapeDBName name ++ "(200)"
escapeDBName' (name, (FTTypeCon _ "String" )) = escapeDBName name ++ "(200)"
escapeDBName' (name, (FTTypeCon _ "ByteString")) = escapeDBName name ++ "(200)"
escapeDBName' (name, _ ) = escapeDBName name
showAlterTable table (DropUniqueConstraint cname) = concat
[ "ALTER TABLE "
, escapeDBName table
, " DROP INDEX "
, escapeDBName cname
]
-- | Render an action that must be done on a column.
showAlter :: DBName -> AlterColumn' -> String
showAlter table (n, Change col) =
concat
[ "ALTER TABLE "
, escapeDBName table
, " CHANGE "
, escapeDBName n
, showColumn col
]
showAlter table (_, Add col) =
concat
[ "ALTER TABLE "
, escapeDBName table
, " ADD COLUMN "
, showColumn col
]
showAlter table (n, Drop) =
concat
[ "ALTER TABLE "
, escapeDBName table
, " DROP COLUMN "
, escapeDBName n
]
showAlter table (n, Default s) =
concat
[ "ALTER TABLE "
, escapeDBName table
, " ALTER COLUMN "
, escapeDBName n
, " SET DEFAULT "
, s
]
showAlter table (n, NoDefault) =
concat
[ "ALTER TABLE "
, escapeDBName table
, " ALTER COLUMN "
, escapeDBName n
, " DROP DEFAULT"
]
showAlter table (n, Update s) =
concat
[ "UPDATE "
, escapeDBName table
, " SET "
, escapeDBName n
, "="
, s
, " WHERE "
, escapeDBName n
, " IS NULL"
]
showAlter table (n, AddReference t2 id2) = concat
[ "ALTER TABLE "
, escapeDBName table
, " ADD CONSTRAINT "
, escapeDBName $ refName table n
, " FOREIGN KEY("
, escapeDBName n
, ") REFERENCES "
, escapeDBName t2
, "("
, escapeDBName id2
, ")"
]
showAlter table (_, DropReference cname) = concat
[ "ALTER TABLE "
, escapeDBName table
, " DROP CONSTRAINT "
, escapeDBName cname
]
refName :: DBName -> DBName -> DBName
refName (DBName table) (DBName column) =
DBName $ T.concat [table, "_", column, "_fkey"]
----------------------------------------------------------------------
-- | Escape a database name to be included on a query.
escapeDBName :: DBName -> String
escapeDBName (DBName s) = '`' : go (T.unpack s)
where
go ('`':xs) = '`' : '`' : go xs
go ( x :xs) = x : go xs
go "" = "`"
-- | Information required to connect to a MySQL database
-- using @persistent@'s generic facilities. These values are the
-- same that are given to 'withMySQLPool'.
data MySQLConf = MySQLConf
{ myConnInfo :: MySQL.ConnectInfo
-- ^ The connection information.
, myPoolSize :: Int
-- ^ How many connections should be held on the connection pool.
}
instance PersistConfig MySQLConf where
type PersistConfigBackend MySQLConf = SqlPersist
type PersistConfigPool MySQLConf = ConnectionPool
createPoolConfig (MySQLConf cs size) = createMySQLPool cs size
runPool _ = runSqlPool
loadConfig (Object o) = do
database <- o .: "database"
host <- o .: "host"
port <- o .: "port"
user <- o .: "user"
password <- o .: "password"
pool <- o .: "poolsize"
let ci = MySQL.defaultConnectInfo
{ MySQL.connectHost = host
, MySQL.connectPort = port
, MySQL.connectUser = user
, MySQL.connectPassword = password
, MySQL.connectDatabase = database
}
return $ MySQLConf ci pool
loadConfig _ = mzero
applyEnv conf = do
env <- getEnvironment
let maybeEnv old var = maybe old id $ lookup ("MYSQL_" ++ var) env
return conf
{ myConnInfo =
case myConnInfo conf of
MySQL.ConnectInfo
{ MySQL.connectHost = host
, MySQL.connectPort = port
, MySQL.connectUser = user
, MySQL.connectPassword = password
, MySQL.connectDatabase = database
} -> (myConnInfo conf)
{ MySQL.connectHost = maybeEnv host "HOST"
, MySQL.connectPort = read $ maybeEnv (show port) "PORT"
, MySQL.connectUser = maybeEnv user "USER"
, MySQL.connectPassword = maybeEnv password "PASSWORD"
, MySQL.connectDatabase = maybeEnv database "DATABASE"
}
}