yesod-persistent-1.4.0.3: Some helpers for using Persistent from Yesod.

Safe HaskellNone
LanguageHaskell98

Yesod.Persist.Core

Description

Defines the core functionality of this package. This package is distinguished from Yesod.Persist in that the latter additionally exports the persistent modules themselves.

Synopsis

Documentation

class Monad (YesodDB site) => YesodPersist site where Source

Associated Types

type YesodPersistBackend site Source

Methods

runDB :: YesodDB site a -> HandlerT site IO a Source

defaultRunDB :: PersistConfig c => (site -> c) -> (site -> PersistConfigPool c) -> PersistConfigBackend c (HandlerT site IO) a -> HandlerT site IO a Source

Helper for creating runDB.

Since 1.2.0

class YesodPersist site => YesodPersistRunner site where Source

Since 1.2.0

Methods

getDBRunner :: HandlerT site IO (DBRunner site, HandlerT site IO ()) Source

This function differs from runDB in that it returns a database runner function, as opposed to simply running a single action. This will usually mean that a connection is taken from a pool and then reused for each invocation. This can be useful for creating streaming responses; see runDBSource.

It additionally returns a cleanup function to free the connection. If your code finishes successfully, you must call this cleanup to indicate changes should be committed. Otherwise, for SQL backends at least, a rollback will be used instead.

Since 1.2.0

defaultGetDBRunner :: (YesodPersistBackend site ~ SqlBackend) => (site -> Pool Connection) -> HandlerT site IO (DBRunner site, HandlerT site IO ()) Source

Helper for implementing getDBRunner.

Since 1.2.0

newtype DBRunner site Source

Constructors

DBRunner 

Fields

runDBRunner :: forall a. YesodDB site a -> HandlerT site IO a
 

runDBSource :: YesodPersistRunner site => Source (YesodDB site) a -> Source (HandlerT site IO) a Source

Like runDB, but transforms a Source. See respondSourceDB for an example, practical use case.

Since 1.2.0

respondSourceDB :: YesodPersistRunner site => ContentType -> Source (YesodDB site) (Flush Builder) -> HandlerT site IO TypedContent Source

Extends respondSource to create a streaming database response body.

get404 :: (MonadIO m, PersistStore (PersistEntityBackend val), PersistEntity val) => Key val -> ReaderT (PersistEntityBackend val) m val Source

Get the given entity by ID, or return a 404 not found if it doesn't exist.

getBy404 :: (PersistUnique (PersistEntityBackend val), PersistEntity val, MonadIO m) => Unique val -> ReaderT (PersistEntityBackend val) m (Entity val) Source

Get the given entity by unique key, or return a 404 not found if it doesn't exist.