Snap.Snaplet.Persistent

Documentation

initPersist :: SqlPersistT (NoLoggingT IO) a -> SnapletInit b PersistState

Initialize Persistent with an initial SQL function called right after the connection pool has been created. This is most useful for calling migrations upfront right after initialization.

Example:

initPersist (runMigrationUnsafe migrateAll)

where migrateAll is the migration function that was auto-generated by the QQ statement in your persistent schema definition in the call to mkMigrate.

initPersistGeneric :: Initializer b PersistState (Pool SqlBackend) -> SqlPersistT (NoLoggingT IO) a -> SnapletInit b PersistState

Backend-agnostic initalization with an initial SQL function called right after the connection pool has been created. This is most useful for calling migrations upfront right after initialization.

Example:

initPersist mkPool (runMigrationUnsafe migrateAll)

where migrateAll is the migration function that was auto-generated by the QQ statement in your persistent schema definition in the call to mkMigrate.

mkPool is a function to construct a pool of connections to your database

newtype PersistState

Constructors

PersistState

Fields

• persistPool :: ConnectionPool

Instances

HasPersistPool (Handler b PersistState)

Methods

getPersistPool :: Handler b PersistState ConnectionPool

class MonadIO m => HasPersistPool m where

Implement this type class to have any monad work with snaplet-persistent. A default instance is provided for (Handler b PersistState).

Minimal complete definition

getPersistPool

Methods

getPersistPool :: m ConnectionPool

Instances

HasPersistPool m => HasPersistPool (NoLoggingT m)

Methods

getPersistPool :: NoLoggingT m ConnectionPool

HasPersistPool (Handler b PersistState)

Methods

getPersistPool :: Handler b PersistState ConnectionPool

MonadIO m => HasPersistPool (ReaderT * ConnectionPool m)

Methods

getPersistPool :: ReaderT * ConnectionPool m ConnectionPool

mkPgPool :: MonadIO m => Config -> m ConnectionPool

Constructs a connection pool from Config.

mkSnapletPgPool :: (MonadIO (m b v), MonadSnaplet m) => m b v ConnectionPool

Conscruts a connection pool in a snaplet context.

runPersist

Arguments

:: HasPersistPool m

=> SqlPersistT (ResourceT (NoLoggingT IO)) b

Run given Persistent action in the defined monad.

-> m b

Runs a SqlPersist action in any monad with a HasPersistPool instance.

withPool :: MonadIO m => ConnectionPool -> SqlPersistT (ResourceT (NoLoggingT IO)) a -> m a

Run a database action

Utility Functions

mkKey :: ToBackendKey SqlBackend entity => Int -> Key entity

Make a Key from an Int.

mkKeyBS :: ToBackendKey SqlBackend entity => ByteString -> Key entity

Makes a Key from a ByteString. Calls error on failure.

mkKeyT :: ToBackendKey SqlBackend entity => Text -> Key entity

Makes a Key from Text. Calls error on failure.

showKey :: ToBackendKey SqlBackend e => Key e -> Text

Makes a Text representation of a Key.

showKeyBS :: ToBackendKey SqlBackend e => Key e -> ByteString

Makes a ByteString representation of a Key.

mkInt :: ToBackendKey SqlBackend a => Key a -> Int

Converts a Key to Int. Fails with error if the conversion fails.

mkWord64 :: ToBackendKey SqlBackend a => Key a -> Word64

Converts a Key to Word64. Fails with error if the conversion fails.

followForeignKey :: (PersistEntity a, HasPersistPool m, PersistEntityBackend a ~ SqlBackend) => (t -> Key a) -> Entity t -> m (Maybe (Entity a))

Follows a foreign key field in one entity and retrieves the corresponding entity from the database.

fromPersistValue' :: PersistField c => PersistValue -> c