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 -> HandlerFor site a

Allows you to execute database actions within Yesod Handlers. For databases that support it, code inside the action will run as an atomic transaction.

Example Usage

userId <- runDB $ do
  userId <- insert $ User "username" "[e-mail]"
  insert_ $ UserPreferences userId True
  pure userId

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

Helper for creating runDB.

Since 1.2.0

class YesodPersist site => YesodPersistRunner site where

Since 1.2.0

Methods

getDBRunner :: HandlerFor site (DBRunner site, HandlerFor site ())

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 :: (IsSqlBackend backend, YesodPersistBackend site ~ backend) => (site -> Pool backend) -> HandlerFor site (DBRunner site, HandlerFor site ())

Helper for implementing getDBRunner.

Since 1.2.0

newtype DBRunner site

Constructors

DBRunner

Fields

• runDBRunner :: forall a. YesodDB site a -> HandlerFor site a

runDBSource :: YesodPersistRunner site => ConduitT () a (YesodDB site) () -> ConduitT () a (HandlerFor site) ()

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

Since 1.2.0

respondSourceDB :: YesodPersistRunner site => ContentType -> ConduitT () (Flush Builder) (YesodDB site) () -> HandlerFor site TypedContent

Extends respondSource to create a streaming database response body.

type YesodDB site = ReaderT (YesodPersistBackend site) (HandlerFor site)

get404 :: (MonadIO m, PersistStoreRead backend, PersistRecordBackend val backend) => Key val -> ReaderT backend m val

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

getBy404 :: (PersistUniqueRead backend, PersistRecordBackend val backend, MonadIO m) => Unique val -> ReaderT backend m (Entity val)

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

insert400 :: (MonadIO m, PersistUniqueWrite backend, PersistRecordBackend val backend, SafeToInsert val) => val -> ReaderT backend m (Key val)

Create a new record in the database, returning an automatically created key, or raise a 400 bad request if a uniqueness constraint is violated.

Since: 1.4.1

insert400_ :: (MonadIO m, PersistUniqueWrite backend, PersistRecordBackend val backend, SafeToInsert val) => val -> ReaderT backend m ()

Same as insert400, but doesn’t return a key.

Since: 1.4.1