{-# LANGUAGE CPP #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE ConstraintKinds #-}
{-# LANGUAGE FlexibleContexts #-}
module Database.Persist.Class.PersistQuery
( PersistQueryRead (..)
, PersistQueryWrite (..)
, selectSource
, selectKeys
, selectList
, selectKeysList
) where
import Database.Persist.Types
import Control.Monad.IO.Class (MonadIO, liftIO)
import Control.Monad.Reader (ReaderT, MonadReader)
import qualified Data.Conduit as C
import qualified Data.Conduit.List as CL
import Database.Persist.Class.PersistStore
import Database.Persist.Class.PersistEntity
import Control.Monad.Trans.Resource (MonadResource, release)
import Data.Acquire (Acquire, allocateAcquire, with)
class (PersistCore backend, PersistStoreRead backend) => PersistQueryRead backend where
selectSourceRes
:: (PersistRecordBackend record backend, MonadIO m1, MonadIO m2)
=> [Filter record]
-> [SelectOpt record]
-> ReaderT backend m1 (Acquire (C.Source m2 (Entity record)))
selectFirst :: (MonadIO m, PersistRecordBackend record backend)
=> [Filter record]
-> [SelectOpt record]
-> ReaderT backend m (Maybe (Entity record))
selectFirst filts opts = do
srcRes <- selectSourceRes filts (LimitTo 1 : opts)
liftIO $ with srcRes (C.$$ CL.head)
selectKeysRes
:: (MonadIO m1, MonadIO m2, PersistRecordBackend record backend)
=> [Filter record]
-> [SelectOpt record]
-> ReaderT backend m1 (Acquire (C.Source m2 (Key record)))
count :: (MonadIO m, PersistRecordBackend record backend)
=> [Filter record] -> ReaderT backend m Int
class (PersistQueryRead backend, PersistStoreWrite backend) => PersistQueryWrite backend where
updateWhere :: (MonadIO m, PersistRecordBackend record backend)
=> [Filter record] -> [Update record] -> ReaderT backend m ()
deleteWhere :: (MonadIO m, PersistRecordBackend record backend)
=> [Filter record] -> ReaderT backend m ()
selectSource
:: (PersistQueryRead (BaseBackend backend), MonadResource m, PersistEntity record, PersistEntityBackend record ~ BaseBackend (BaseBackend backend), MonadReader backend m, HasPersistBackend backend)
=> [Filter record]
-> [SelectOpt record]
-> C.Source m (Entity record)
selectSource filts opts = do
srcRes <- liftPersist $ selectSourceRes filts opts
(releaseKey, src) <- allocateAcquire srcRes
src
release releaseKey
selectKeys :: (PersistQueryRead (BaseBackend backend), MonadResource m, PersistEntity record, BaseBackend (BaseBackend backend) ~ PersistEntityBackend record, MonadReader backend m, HasPersistBackend backend)
=> [Filter record]
-> [SelectOpt record]
-> C.Source m (Key record)
selectKeys filts opts = do
srcRes <- liftPersist $ selectKeysRes filts opts
(releaseKey, src) <- allocateAcquire srcRes
src
release releaseKey
selectList :: (MonadIO m, PersistQueryRead backend, PersistRecordBackend record backend)
=> [Filter record]
-> [SelectOpt record]
-> ReaderT backend m [Entity record]
selectList filts opts = do
srcRes <- selectSourceRes filts opts
liftIO $ with srcRes (C.$$ CL.consume)
selectKeysList :: (MonadIO m, PersistQueryRead backend, PersistRecordBackend record backend)
=> [Filter record]
-> [SelectOpt record]
-> ReaderT backend m [Key record]
selectKeysList filts opts = do
srcRes <- selectKeysRes filts opts
liftIO $ with srcRes (C.$$ CL.consume)