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{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE CPP #-}
{-# LANGUAGE OverloadedStrings #-}
module Database.Persist.Query.Join.Sql
( RunJoin (..)
) where
import Database.Persist.Query.Join hiding (RunJoin (..))
import Database.Persist.EntityDef
import qualified Database.Persist.Query.Join as J
import Database.Persist.Store
import Database.Persist.Query.Internal
import Database.Persist.Query.GenericSql
import Control.Monad (liftM)
import Data.Maybe (mapMaybe)
import Data.List (groupBy)
import Database.Persist.GenericSql
import Database.Persist.GenericSql.Internal hiding (withStmt)
import Database.Persist.GenericSql.Raw (withStmt)
import Control.Monad.Trans.Reader (ask)
import Data.Function (on)
import Control.Arrow ((&&&))
import Data.Text (Text, concat, null)
import Prelude hiding ((++), unlines, concat, show, null)
import Data.Monoid (Monoid, mappend)
import qualified Data.Text as T
import qualified Data.Conduit as C
import qualified Data.Conduit.List as CL
import Control.Monad.IO.Class (MonadIO)
import Control.Monad.Trans.Control (MonadBaseControl)
fromPersistValuesId :: PersistEntity v => [PersistValue] -> Either Text (Entity v)
fromPersistValuesId [] = Left "fromPersistValuesId: No values provided"
fromPersistValuesId (PersistInt64 i:rest) =
case fromPersistValues rest of
Left e -> Left e
Right x -> Right (Entity (Key $ PersistInt64 i) x)
fromPersistValuesId _ = Left "fromPersistValuesId: invalid ID"
class RunJoin a where
runJoin :: (C.MonadThrow m, C.MonadUnsafeIO m, MonadIO m, MonadBaseControl IO m) => a -> SqlPersist m (J.Result a)
instance (PersistEntity one, PersistEntity many, Eq (Key SqlPersist one))
=> RunJoin (SelectOneMany SqlPersist one many) where
runJoin (SelectOneMany oneF oneO manyF manyO eq _getKey isOuter) = do
conn <- SqlPersist ask
C.runResourceT $ liftM go $ withStmt (sql conn) (getFiltsValues conn oneF ++ getFiltsValues conn manyF) C.$$ loop id
where
go :: [(Entity b, Maybe (Entity d))]
-> [(Entity b, [Entity d])]
go = map (fst . head &&& mapMaybe snd)
. groupBy ((==) `on` (entityKey . fst))
loop front = do
x <- CL.head
case x of
Nothing -> return $ front []
Just vals -> do
let (y, z) = splitAt oneCount vals
case (fromPersistValuesId y, fromPersistValuesId z) of
(Right y', Right z') -> loop (front . (:) (y', Just z'))
(Left e, _) -> error $ "selectOneMany: " ++ T.unpack e
(Right y', Left e) ->
case z of
PersistNull:_ -> loop (front . (:) (y', Nothing))
_ -> error $ "selectOneMany: " ++ T.unpack e
oneCount = 1 + length (entityFields $ entityDef one)
one = dummyFromFilts oneF
many = dummyFromFilts manyF
sql conn = concat
[ "SELECT "
, T.intercalate "," $ colsPlusId conn one ++ colsPlusId conn many
, " FROM "
, escapeName conn $ entityDB $ entityDef one
, if isOuter then " LEFT JOIN " else " INNER JOIN "
, escapeName conn $ entityDB $ entityDef many
, " ON "
, escapeName conn $ entityDB $ entityDef one
, ".id = "
, escapeName conn $ entityDB $ entityDef many
, "."
, escapeName conn $ filterName $ eq undefined
, onFilts
, whereFilts
, case ords of
[] -> ""
_ -> " ORDER BY " ++ T.intercalate ", " ords
]
where
filts1 = filterClauseNoWhere True conn oneF
filts2 = (if isOuter then filterClauseNoWhereOrNull else filterClauseNoWhere) True conn manyF
whereFilts
| isOuter =
if null filts1
then ""
else " WHERE " ++ filts1
| null filts1 && null filts2 = ""
| null filts1 = " WHERE " ++ filts2
| null filts2 = " WHERE " ++ filts1
| otherwise = " WHERE " ++ filts1 ++ " AND " ++ filts2
onFilts
| isOuter && not (null filts2) = " AND " ++ filts2
| otherwise = ""
orders :: PersistEntity val
=> [SelectOpt val]
-> [SelectOpt val]
orders x = let (_, _, y) = limitOffsetOrder x in y
ords = map (orderClause True conn) (orders oneO) ++ map (orderClause True conn) (orders manyO)
addTable :: PersistEntity val
=> Connection
-> val
-> Text
-> Text
addTable conn e s = concat
[ escapeName conn $ entityDB $ entityDef e
, "."
, s
]
colsPlusId :: PersistEntity e => Connection -> e -> [Text]
colsPlusId conn e =
map (addTable conn e) $
id_ : (map (escapeName conn . fieldDB) cols)
where
id_ = escapeName conn $ entityID $ entityDef e
cols = entityFields $ entityDef e
filterName :: PersistEntity v => Filter v -> DBName
filterName (Filter f _ _) = fieldDB $ persistFieldDef f
filterName (FilterAnd _) = error "expected a raw filter, not an And"
filterName (FilterOr _) = error "expected a raw filter, not an Or"
infixr 5 ++
(++) :: Monoid m => m -> m -> m
(++) = mappend
|
