Yesod.Persist.Core

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

Documentation

class Monad (YesodDB site) => YesodPersist site where

Associated Types

type YesodPersistBackend site

Methods

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

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

Helper for creating runDB.

Since 1.2.0

class YesodPersist site => YesodPersistRunner site where

Since 1.2.0

Methods

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

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 ())

Helper for implementing getDBRunner.

Since 1.2.0

newtype DBRunner site

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

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

Extends respondSource to create a streaming database response body.

type YesodDB site = ReaderT (YesodPersistBackend site) (HandlerT site IO)

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

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)

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