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 (YesodPersistBackend site (HandlerT site IO)) => 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 ~ SqlPersistT => (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 = YesodPersistBackend site (HandlerT site IO)

get404 :: (PersistStore (t m), PersistEntity val, Monad (t m), m ~ HandlerT site IO, MonadTrans t, PersistMonadBackend (t m) ~ PersistEntityBackend val) => Key val -> t m val

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

getBy404 :: (PersistUnique (t m), PersistEntity val, m ~ HandlerT site IO, Monad (t m), MonadTrans t, PersistEntityBackend val ~ PersistMonadBackend (t m)) => Unique val -> t m (Entity val)

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