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{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE CPP #-}
{-# LANGUAGE FlexibleContexts #-}
-- | A postgresql backend for persistent.
module Database.Persist.Postgresql
( withPostgresqlPool
, withPostgresqlConn
, createPostgresqlPool
, module Database.Persist
, module Database.Persist.GenericSql
, ConnectionString
, PostgresConf (..)
) where
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.PostgreSQL.Simple as PG
import qualified Database.PostgreSQL.Simple.BuiltinTypes as PG
import qualified Database.PostgreSQL.Simple.Internal as PG
import qualified Database.PostgreSQL.Simple.ToField as PGTF
import qualified Database.PostgreSQL.Simple.FromField as PGFF
import qualified Database.PostgreSQL.Simple.Types as PG
import Database.PostgreSQL.Simple.Ok (Ok (..))
import qualified Database.PostgreSQL.LibPQ as LibPQ
import Control.Exception (throw)
import Control.Monad.IO.Class (MonadIO (..))
import Control.Monad.Trans.Control (MonadBaseControl)
import Data.List (intercalate)
import Data.IORef
import qualified Data.Map as Map
import Data.Either (partitionEithers)
import Control.Arrow
import Data.List (sort, groupBy)
import Data.Function (on)
import qualified Data.Conduit as C
import qualified Data.Conduit.List as CL
import Data.ByteString (ByteString)
import qualified Data.ByteString.Char8 as B8
import qualified Data.Text as T
import qualified Data.Text.Encoding as T
-- import Data.Time.LocalTime (localTimeToUTC, utc)
import Data.Text (Text, pack)
import Data.Aeson
import Control.Monad (forM, mzero)
import System.Environment (getEnvironment)
-- | A @libpq@ connection string. A simple example of connection
-- string would be @\"host=localhost port=5432 user=test
-- dbname=test password=test\"@. Please read libpq's
-- documentation at
-- <http://www.postgresql.org/docs/9.1/static/libpq-connect.html>
-- for more details on how to create such strings.
type ConnectionString = ByteString
-- | Create a PostgreSQL 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.
withPostgresqlPool :: MonadIO m
=> ConnectionString
-- ^ Connection string to the database.
-> 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
withPostgresqlPool ci = withSqlPool $ open' ci
-- | Create a PostgreSQL connection pool. Note that it's your
-- responsability to properly close the connection pool when
-- unneeded. Use 'withPostgresqlPool' for an automatic resource
-- control.
createPostgresqlPool :: MonadIO m
=> ConnectionString
-- ^ Connection string to the database.
-> Int
-- ^ Number of connections to be kept open
-- in the pool.
-> m ConnectionPool
createPostgresqlPool ci = createSqlPool $ open' ci
-- | Same as 'withPostgresqlPool', but instead of opening a pool
-- of connections, only one connection is opened.
withPostgresqlConn :: (MonadIO m, MonadBaseControl IO m)
=> ConnectionString -> (Connection -> m a) -> m a
withPostgresqlConn = withSqlConn . open'
open' :: ConnectionString -> IO Connection
open' cstr = do
conn <- PG.connectPostgreSQL cstr
smap <- newIORef $ Map.empty
return Connection
{ prepare = prepare' conn
, stmtMap = smap
, insertSql = insertSql'
, close = PG.close conn
, migrateSql = migrate'
, begin = const $ PG.begin conn
, commitC = const $ PG.commit conn
, rollbackC = const $ PG.rollback conn
, escapeName = escape
, noLimit = "LIMIT ALL"
}
prepare' :: PG.Connection -> Text -> IO Statement
prepare' conn sql = do
let query = PG.Query (T.encodeUtf8 sql)
return Statement
{ finalize = return ()
, reset = return ()
, execute = execute' conn query
, withStmt = withStmt' conn query
}
insertSql' :: DBName -> [DBName] -> Either Text (Text, Text)
insertSql' t cols = Left $ pack $ concat
[ "INSERT INTO "
, T.unpack $ escape t
, "("
, intercalate "," $ map (T.unpack . escape) cols
, ") VALUES("
, intercalate "," (map (const "?") cols)
, ") RETURNING id"
]
execute' :: PG.Connection -> PG.Query -> [PersistValue] -> IO ()
execute' conn query vals = do
_ <- PG.execute conn query (map P vals)
return ()
withStmt' :: C.MonadResource m
=> PG.Connection
-> PG.Query
-> [PersistValue]
-> C.Source m [PersistValue]
withStmt' conn query vals = C.sourceIO (liftIO openS )
(liftIO . closeS)
(liftIO . pullS )
where
openS = do
-- Construct raw query
rawquery <- PG.formatQuery conn query (map P vals)
-- Take raw connection
PG.withConnection conn $ \rawconn -> do
-- Execute query
mret <- LibPQ.exec rawconn rawquery
case mret of
Nothing -> do
merr <- LibPQ.errorMessage rawconn
fail $ case merr of
Nothing -> "Postgresql.withStmt': unknown error"
Just e -> "Postgresql.withStmt': " ++ B8.unpack e
Just ret -> do
-- Check result status
status <- LibPQ.resultStatus ret
case status of
LibPQ.TuplesOk -> return ()
_ -> do
msg <- LibPQ.resStatus status
fail $ "Postgresql.withStmt': bad result status " ++
show status ++ " (" ++ show msg ++ ")"
-- Get number and type of columns
cols <- LibPQ.nfields ret
getters <- forM [0..cols-1] $ \col -> do
oid <- LibPQ.ftype ret col
case PG.oid2builtin oid of
Nothing -> fail $ "Postgresql.withStmt': could not " ++
"recognize Oid of column " ++
show (let LibPQ.Col i = col in i) ++
" (counting from zero)"
Just bt -> return $ getGetter bt $
PG.Field ret col $
PG.builtin2typname bt
-- Ready to go!
rowRef <- newIORef (LibPQ.Row 0)
rowCount <- LibPQ.ntuples ret
return (ret, rowRef, rowCount, getters)
closeS (ret, _, _, _) = LibPQ.unsafeFreeResult ret
pullS (ret, rowRef, rowCount, getters) = do
row <- atomicModifyIORef rowRef (\r -> (r+1, r))
if row == rowCount
then return C.IOClosed
else fmap C.IOOpen $ forM (zip getters [0..]) $ \(getter, col) -> do
mbs <- LibPQ.getvalue' ret row col
case mbs of
Nothing -> return PersistNull
Just bs -> bs `seq` case getter mbs of
Errors (exc:_) -> throw exc
Errors [] -> error "Got an Errors, but no exceptions"
Ok v -> return v
-- | Avoid orphan instances.
newtype P = P PersistValue
instance PGTF.ToField P where
toField (P (PersistText t)) = PGTF.toField t
toField (P (PersistByteString bs)) = PGTF.toField (PG.Binary bs)
toField (P (PersistInt64 i)) = PGTF.toField i
toField (P (PersistDouble d)) = PGTF.toField d
toField (P (PersistBool b)) = PGTF.toField b
toField (P (PersistDay d)) = PGTF.toField d
toField (P (PersistTimeOfDay t)) = PGTF.toField t
toField (P (PersistUTCTime t)) = PGTF.toField t
toField (P (PersistZonedTime (ZT t))) = PGTF.toField t
toField (P PersistNull) = PGTF.toField PG.Null
toField (P (PersistList l)) = PGTF.toField $ listToJSON l
toField (P (PersistMap m)) = PGTF.toField $ mapToJSON m
toField (P (PersistObjectId _)) =
error "Refusing to serialize a PersistObjectId to a PostgreSQL value"
type Getter a = PG.Field -> Maybe ByteString -> Ok a
convertPV :: PGFF.FromField a => (a -> b) -> Getter b
convertPV f = (fmap f .) . PGFF.fromField
-- FIXME: check if those are correct and complete.
getGetter :: PG.BuiltinType -> Getter PersistValue
getGetter PG.Bool = convertPV PersistBool
getGetter PG.Bytea = convertPV (PersistByteString . unBinary)
getGetter PG.Char = convertPV PersistText
getGetter PG.Name = convertPV PersistText
getGetter PG.Int8 = convertPV PersistInt64
getGetter PG.Int2 = convertPV PersistInt64
getGetter PG.Int4 = convertPV PersistInt64
getGetter PG.Text = convertPV PersistText
getGetter PG.Xml = convertPV PersistText
getGetter PG.Float4 = convertPV PersistDouble
getGetter PG.Float8 = convertPV PersistDouble
getGetter PG.Abstime = convertPV PersistUTCTime
getGetter PG.Reltime = convertPV PersistUTCTime
getGetter PG.Money = convertPV PersistDouble
getGetter PG.Bpchar = convertPV PersistText
getGetter PG.Varchar = convertPV PersistText
getGetter PG.Date = convertPV PersistDay
getGetter PG.Time = convertPV PersistTimeOfDay
getGetter PG.Timestamp = convertPV PersistUTCTime
getGetter PG.TimestampWithTimeZone = convertPV (PersistZonedTime . ZT)
getGetter PG.Bit = convertPV PersistInt64
getGetter PG.Varbit = convertPV PersistInt64
getGetter PG.Numeric = convertPV (PersistDouble . fromRational)
getGetter PG.Void = \_ _ -> Ok PersistNull
getGetter other = error $ "Postgresql.getGetter: type " ++
show other ++ " not supported."
unBinary :: PG.Binary a -> a
unBinary (PG.Binary x) = x
migrate' :: PersistEntity val
=> [EntityDef]
-> (Text -> IO Statement)
-> val
-> IO (Either [Text] [(Bool, Text)])
migrate' allDefs getter val = do
let name = entityDB $ entityDef val
old <- getColumns getter $ entityDef val
case partitionEithers old of
([], old'') -> do
let old' = partitionEithers old''
let new = second (map udToPair) $ mkColumns allDefs val
if null old
then do
let addTable = AddTable $ concat
[ "CREATE TABLE "
, T.unpack $ escape name
, "("
, T.unpack $ escape $ entityID $ entityDef val
, " SERIAL PRIMARY KEY UNIQUE"
, concatMap (\x -> ',' : showColumn x) $ fst new
, ")"
]
let rest = flip concatMap (snd new) $ \(uname, ucols) ->
[AlterTable name $ AddUniqueConstraint uname ucols]
return $ Right $ map showAlterDb $ addTable : rest
else do
let (acs, ats) = getAlters new old'
let acs' = map (AlterColumn name) acs
let ats' = map (AlterTable name) ats
return $ Right $ map showAlterDb $ acs' ++ ats'
(errs, _) -> return $ Left errs
data AlterColumn = Type SqlType | IsNull | NotNull | Add Column | Drop
| Default String | NoDefault | Update String
| AddReference DBName | DropReference DBName
type AlterColumn' = (DBName, AlterColumn)
data AlterTable = AddUniqueConstraint DBName [DBName]
| DropConstraint DBName
data AlterDB = AddTable String
| AlterColumn DBName AlterColumn'
| AlterTable DBName AlterTable
-- | Returns all of the columns in the given table currently in the database.
getColumns :: (Text -> IO Statement)
-> EntityDef
-> IO [Either Text (Either Column (DBName, [DBName]))]
getColumns getter def = do
stmt <- getter "SELECT column_name,is_nullable,udt_name,column_default FROM information_schema.columns WHERE table_name=? AND column_name <> ?"
let vals =
[ PersistText $ unDBName $ entityDB def
, PersistText $ unDBName $ entityID def
]
cs <- C.runResourceT $ withStmt stmt vals C.$$ helper
stmt' <- getter
"SELECT constraint_name, column_name FROM information_schema.constraint_column_usage WHERE table_name=? AND column_name <> ? ORDER BY constraint_name, column_name"
us <- C.runResourceT $ withStmt stmt' vals C.$$ helperU
return $ cs ++ us
where
getAll front = do
x <- CL.head
case x of
Nothing -> return $ front []
Just [PersistText con, PersistText col] ->
getAll (front . (:) (con, col))
Just _ -> getAll front -- FIXME error message?
helperU = do
rows <- getAll id
return $ map (Right . Right . (DBName . fst . head &&& map (DBName . snd)))
$ groupBy ((==) `on` fst) rows
helper = do
x <- CL.head
case x of
Nothing -> return []
Just x' -> do
col <- liftIO $ getColumn getter (entityDB def) x'
let col' = case col of
Left e -> Left e
Right c -> Right $ Left c
cols <- helper
return $ col' : cols
getAlters :: ([Column], [(DBName, [DBName])])
-> ([Column], [(DBName, [DBName])])
-> ([AlterColumn'], [AlterTable])
getAlters (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 new old
in alters ++ getAltersC news old'
getAltersU :: [(DBName, [DBName])]
-> [(DBName, [DBName])]
-> [AlterTable]
getAltersU [] old = map (DropConstraint . fst) old
getAltersU ((name, cols):news) old =
case lookup name old of
Nothing -> AddUniqueConstraint name cols : getAltersU news old
Just ocols ->
let old' = filter (\(x, _) -> x /= name) old
in if sort cols == ocols
then getAltersU news old'
else DropConstraint name
: AddUniqueConstraint name cols
: getAltersU news old'
getColumn :: (Text -> IO Statement)
-> DBName -> [PersistValue]
-> IO (Either Text Column)
getColumn getter tname [PersistText x, PersistText y, PersistText z, d] =
case d' of
Left s -> return $ Left s
Right d'' ->
case getType z of
Left s -> return $ Left s
Right t -> do
let cname = DBName x
ref <- getRef cname
return $ Right $ Column cname (y == "YES") t d'' Nothing ref
where
getRef cname = do
let sql = pack $ concat
[ "SELECT COUNT(*) FROM "
, "information_schema.table_constraints "
, "WHERE table_name=? "
, "AND constraint_type='FOREIGN KEY' "
, "AND constraint_name=?"
]
let ref = refName tname cname
stmt <- getter sql
C.runResourceT $ withStmt stmt
[ PersistText $ unDBName tname
, PersistText $ unDBName ref
] C.$$ do
Just [PersistInt64 i] <- CL.head
return $ if i == 0 then Nothing else Just (DBName "", ref)
d' = case d of
PersistNull -> Right Nothing
PersistText t -> Right $ Just t
_ -> Left $ pack $ "Invalid default column: " ++ show d
getType "int4" = Right $ SqlInt32
getType "int8" = Right $ SqlInteger
getType "varchar" = Right $ SqlString
getType "date" = Right $ SqlDay
getType "bool" = Right $ SqlBool
getType "timestamp" = Right $ SqlDayTime
getType "timestamptz" = Right $ SqlDayTimeZoned
getType "float4" = Right $ SqlReal
getType "float8" = Right $ SqlReal
getType "bytea" = Right $ SqlBlob
getType "time" = Right $ SqlTime
getType a = Left $ "Unknown type: " `T.append` a
getColumn _ _ x =
return $ Left $ pack $ "Invalid result from information_schema: " ++ show x
findAlters :: Column -> [Column] -> ([AlterColumn'], [Column])
findAlters col@(Column name isNull type_ def _maxLen ref) cols =
case filter (\c -> cName c == name) cols of
[] -> ([(name, Add col)], cols)
Column _ isNull' type_' def' _maxLen' ref':_ ->
let refDrop Nothing = []
refDrop (Just (_, cname)) = [(name, DropReference cname)]
refAdd Nothing = []
refAdd (Just (tname, _)) = [(name, AddReference tname)]
modRef =
if fmap snd ref == fmap snd ref'
then []
else refDrop ref' ++ refAdd ref
modNull = case (isNull, isNull') of
(True, False) -> [(name, IsNull)]
(False, True) ->
let up = case def of
Nothing -> id
Just s -> (:) (name, Update $ T.unpack s)
in up [(name, NotNull)]
_ -> []
modType = if type_ == type_' then [] else [(name, Type type_)]
modDef =
if def == def'
then []
else case def of
Nothing -> [(name, NoDefault)]
Just s -> [(name, Default $ T.unpack s)]
in (modRef ++ modDef ++ modNull ++ modType,
filter (\c -> cName c /= name) cols)
showColumn :: Column -> String
showColumn (Column n nu t def _maxLen ref) = concat
[ T.unpack $ escape n
, " "
, showSqlType t
, " "
, if nu then "NULL" else "NOT NULL"
, case def of
Nothing -> ""
Just s -> " DEFAULT " ++ T.unpack s
, case ref of
Nothing -> ""
Just (s, _) -> " REFERENCES " ++ T.unpack (escape s)
]
showSqlType :: SqlType -> String
showSqlType SqlString = "VARCHAR"
showSqlType SqlInt32 = "INT4"
showSqlType SqlInteger = "INT8"
showSqlType SqlReal = "DOUBLE PRECISION"
showSqlType SqlDay = "DATE"
showSqlType SqlTime = "TIME"
showSqlType SqlDayTime = "TIMESTAMP"
showSqlType SqlDayTimeZoned = "TIMESTAMP WITH TIME ZONE"
showSqlType SqlBlob = "BYTEA"
showSqlType SqlBool = "BOOLEAN"
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)
showAlterTable :: DBName -> AlterTable -> String
showAlterTable table (AddUniqueConstraint cname cols) = concat
[ "ALTER TABLE "
, T.unpack $ escape table
, " ADD CONSTRAINT "
, T.unpack $ escape cname
, " UNIQUE("
, intercalate "," $ map (T.unpack . escape) cols
, ")"
]
showAlterTable table (DropConstraint cname) = concat
[ "ALTER TABLE "
, T.unpack $ escape table
, " DROP CONSTRAINT "
, T.unpack $ escape cname
]
showAlter :: DBName -> AlterColumn' -> String
showAlter table (n, Type t) =
concat
[ "ALTER TABLE "
, T.unpack $ escape table
, " ALTER COLUMN "
, T.unpack $ escape n
, " TYPE "
, showSqlType t
]
showAlter table (n, IsNull) =
concat
[ "ALTER TABLE "
, T.unpack $ escape table
, " ALTER COLUMN "
, T.unpack $ escape n
, " DROP NOT NULL"
]
showAlter table (n, NotNull) =
concat
[ "ALTER TABLE "
, T.unpack $ escape table
, " ALTER COLUMN "
, T.unpack $ escape n
, " SET NOT NULL"
]
showAlter table (_, Add col) =
concat
[ "ALTER TABLE "
, T.unpack $ escape table
, " ADD COLUMN "
, showColumn col
]
showAlter table (n, Drop) =
concat
[ "ALTER TABLE "
, T.unpack $ escape table
, " DROP COLUMN "
, T.unpack $ escape n
]
showAlter table (n, Default s) =
concat
[ "ALTER TABLE "
, T.unpack $ escape table
, " ALTER COLUMN "
, T.unpack $ escape n
, " SET DEFAULT "
, s
]
showAlter table (n, NoDefault) = concat
[ "ALTER TABLE "
, T.unpack $ escape table
, " ALTER COLUMN "
, T.unpack $ escape n
, " DROP DEFAULT"
]
showAlter table (n, Update s) = concat
[ "UPDATE "
, T.unpack $ escape table
, " SET "
, T.unpack $ escape n
, "="
, s
, " WHERE "
, T.unpack $ escape n
, " IS NULL"
]
showAlter table (n, AddReference t2) = concat
[ "ALTER TABLE "
, T.unpack $ escape table
, " ADD CONSTRAINT "
, T.unpack $ escape $ refName table n
, " FOREIGN KEY("
, T.unpack $ escape n
, ") REFERENCES "
, T.unpack $ escape t2
]
showAlter table (_, DropReference cname) = concat
[ "ALTER TABLE "
, T.unpack (escape table)
, " DROP CONSTRAINT "
, T.unpack $ escape cname
]
escape :: DBName -> Text
escape (DBName s) =
T.pack $ '"' : go (T.unpack s) ++ "\""
where
go "" = ""
go ('"':xs) = "\"\"" ++ go xs
go (x:xs) = x : go xs
-- | Information required to connect to a PostgreSQL database
-- using @persistent@'s generic facilities. These values are the
-- same that are given to 'withPostgresqlPool'.
data PostgresConf = PostgresConf
{ pgConnStr :: ConnectionString
-- ^ The connection string.
, pgPoolSize :: Int
-- ^ How many connections should be held on the connection pool.
}
instance PersistConfig PostgresConf where
type PersistConfigBackend PostgresConf = SqlPersist
type PersistConfigPool PostgresConf = ConnectionPool
createPoolConfig (PostgresConf cs size) = createPostgresqlPool 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 = PG.ConnectInfo
{ PG.connectHost = host
, PG.connectPort = port
, PG.connectUser = user
, PG.connectPassword = password
, PG.connectDatabase = database
}
cstr = PG.postgreSQLConnectionString ci
return $ PostgresConf cstr pool
loadConfig _ = mzero
applyEnv c0 = do
env <- getEnvironment
return $ addUser env
$ addPass env
$ addDatabase env
$ addPort env
$ addHost env c0
where
addParam param val c =
c { pgConnStr = B8.concat [pgConnStr c, " ", param, "='", pgescape val, "'"] }
pgescape = B8.pack . go
where
go ('\'':rest) = '\\' : '\'' : go rest
go ('\\':rest) = '\\' : '\\' : go rest
go ( x :rest) = x : go rest
go [] = []
maybeAddParam param envvar env =
maybe id (addParam param) $
lookup envvar env
addHost = maybeAddParam "host" "PGHOST"
addPort = maybeAddParam "port" "PGPORT"
addUser = maybeAddParam "user" "PGUSER"
addPass = maybeAddParam "password" "PGPASS"
addDatabase = maybeAddParam "dbname" "PGDATABASE"
refName :: DBName -> DBName -> DBName
refName (DBName table) (DBName column) =
DBName $ T.concat [table, "_", column, "_fkey"]
udToPair :: UniqueDef -> (DBName, [DBName])
udToPair ud = (uniqueDBName ud, map snd $ uniqueFields ud)
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