c00259b3fe
git-subtree-dir: yesod-persistent git-subtree-mainline:894336a482git-subtree-split:17e7ae34d4
42 lines
1.2 KiB
Haskell
42 lines
1.2 KiB
Haskell
{-# LANGUAGE TypeFamilies #-}
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{-# LANGUAGE FlexibleContexts #-}
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module Yesod.Persist
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( YesodPersist (..)
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, get404
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, getBy404
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, module Database.Persist
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, module Database.Persist.TH
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) where
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import Database.Persist
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import Database.Persist.TH
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import Control.Monad.Trans.Class (MonadTrans (..))
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import Control.Failure (Failure)
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import Yesod.Handler
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class YesodPersist y where
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type YesodDB y :: (* -> *) -> * -> *
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runDB :: YesodDB y (GGHandler sub y IO) a -> GHandler sub y a
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-- | Get the given entity by ID, or return a 404 not found if it doesn't exist.
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get404 :: (PersistBackend (t m), PersistEntity val, Monad (t m),
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Failure ErrorResponse m, MonadTrans t)
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=> Key val -> t m val
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get404 key = do
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mres <- get key
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case mres of
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Nothing -> lift notFound
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Just res -> return res
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-- | Get the given entity by unique key, or return a 404 not found if it doesn't
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-- exist.
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getBy404 :: (PersistBackend (t m), PersistEntity val, Monad (t m),
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Failure ErrorResponse m, MonadTrans t)
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=> Unique val -> t m (Key val, val)
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getBy404 key = do
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mres <- getBy key
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case mres of
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Nothing -> lift notFound
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Just res -> return res
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