Database.Persist.Typed

This module defines types and helpers for type-safe access to multiple database schema.

Schema Definition

mkSqlSettingsFor :: Name -> MkPersistSettings

Use the SqlFor type for the database connection backend. Use this instead of sqlSettings and provide a quoted type name.

data MainDb

share [ mkPersist (mkSqlSettingsFor ''MainDb), mkMigrate "migrateAll" ] [persistLowerCase|

User
    name Text
    age  Int

    deriving Show Eq
|]

The entities generated will have the PersistEntityBackend defined to be SqlFor MainDb instead of SqlBackend. This is what provides the type safety.

Since: 0.0.1.0

newtype SqlFor db

A wrapper around SqlBackend type. To specialize this to a specific database, fill in the type parameter.

Since: 0.0.1.0

Constructors

SqlFor

Fields

• unSqlFor :: SqlBackend

Instances

BackendCompatible SqlBackend (SqlFor db)

Defined in Database.Persist.Typed

Methods

projectBackend :: SqlFor db -> SqlBackend

Bounded (BackendKey (SqlFor a))

Defined in Database.Persist.Typed

Methods

minBound :: BackendKey (SqlFor a)

maxBound :: BackendKey (SqlFor a)

Enum (BackendKey (SqlFor a))

Defined in Database.Persist.Typed

Methods

succ :: BackendKey (SqlFor a) -> BackendKey (SqlFor a)

pred :: BackendKey (SqlFor a) -> BackendKey (SqlFor a)

toEnum :: Int -> BackendKey (SqlFor a)

fromEnum :: BackendKey (SqlFor a) -> Int

enumFrom :: BackendKey (SqlFor a) -> [BackendKey (SqlFor a)]

enumFromThen :: BackendKey (SqlFor a) -> BackendKey (SqlFor a) -> [BackendKey (SqlFor a)]

enumFromTo :: BackendKey (SqlFor a) -> BackendKey (SqlFor a) -> [BackendKey (SqlFor a)]

enumFromThenTo :: BackendKey (SqlFor a) -> BackendKey (SqlFor a) -> BackendKey (SqlFor a) -> [BackendKey (SqlFor a)]

Eq (BackendKey (SqlFor a))

Defined in Database.Persist.Typed

Methods

(==) :: BackendKey (SqlFor a) -> BackendKey (SqlFor a) -> Bool

(/=) :: BackendKey (SqlFor a) -> BackendKey (SqlFor a) -> Bool

Integral (BackendKey (SqlFor a))

Defined in Database.Persist.Typed

Methods

quot :: BackendKey (SqlFor a) -> BackendKey (SqlFor a) -> BackendKey (SqlFor a)

rem :: BackendKey (SqlFor a) -> BackendKey (SqlFor a) -> BackendKey (SqlFor a)

div :: BackendKey (SqlFor a) -> BackendKey (SqlFor a) -> BackendKey (SqlFor a)

mod :: BackendKey (SqlFor a) -> BackendKey (SqlFor a) -> BackendKey (SqlFor a)

quotRem :: BackendKey (SqlFor a) -> BackendKey (SqlFor a) -> (BackendKey (SqlFor a), BackendKey (SqlFor a))

divMod :: BackendKey (SqlFor a) -> BackendKey (SqlFor a) -> (BackendKey (SqlFor a), BackendKey (SqlFor a))

toInteger :: BackendKey (SqlFor a) -> Integer

Num (BackendKey (SqlFor a))

Defined in Database.Persist.Typed

Methods

(+) :: BackendKey (SqlFor a) -> BackendKey (SqlFor a) -> BackendKey (SqlFor a)

(-) :: BackendKey (SqlFor a) -> BackendKey (SqlFor a) -> BackendKey (SqlFor a)

(*) :: BackendKey (SqlFor a) -> BackendKey (SqlFor a) -> BackendKey (SqlFor a)

negate :: BackendKey (SqlFor a) -> BackendKey (SqlFor a)

abs :: BackendKey (SqlFor a) -> BackendKey (SqlFor a)

signum :: BackendKey (SqlFor a) -> BackendKey (SqlFor a)

fromInteger :: Integer -> BackendKey (SqlFor a)

Ord (BackendKey (SqlFor a))

Defined in Database.Persist.Typed

Methods

compare :: BackendKey (SqlFor a) -> BackendKey (SqlFor a) -> Ordering

(<) :: BackendKey (SqlFor a) -> BackendKey (SqlFor a) -> Bool

(<=) :: BackendKey (SqlFor a) -> BackendKey (SqlFor a) -> Bool

(>) :: BackendKey (SqlFor a) -> BackendKey (SqlFor a) -> Bool

(>=) :: BackendKey (SqlFor a) -> BackendKey (SqlFor a) -> Bool

max :: BackendKey (SqlFor a) -> BackendKey (SqlFor a) -> BackendKey (SqlFor a)

min :: BackendKey (SqlFor a) -> BackendKey (SqlFor a) -> BackendKey (SqlFor a)

Read (BackendKey (SqlFor a))

Defined in Database.Persist.Typed

Methods

readsPrec :: Int -> ReadS (BackendKey (SqlFor a))

readList :: ReadS [BackendKey (SqlFor a)]

readPrec :: ReadPrec (BackendKey (SqlFor a))

readListPrec :: ReadPrec [BackendKey (SqlFor a)]

Real (BackendKey (SqlFor a))

Defined in Database.Persist.Typed

Methods

toRational :: BackendKey (SqlFor a) -> Rational

Show (BackendKey (SqlFor a))

Defined in Database.Persist.Typed

Methods

showsPrec :: Int -> BackendKey (SqlFor a) -> ShowS

show :: BackendKey (SqlFor a) -> String

showList :: [BackendKey (SqlFor a)] -> ShowS

ToJSON (BackendKey (SqlFor a))

Defined in Database.Persist.Typed

Methods

toJSON :: BackendKey (SqlFor a) -> Value

toEncoding :: BackendKey (SqlFor a) -> Encoding

toJSONList :: [BackendKey (SqlFor a)] -> Value

toEncodingList :: [BackendKey (SqlFor a)] -> Encoding

FromJSON (BackendKey (SqlFor a))

Defined in Database.Persist.Typed

Methods

parseJSON :: Value -> Parser (BackendKey (SqlFor a))

parseJSONList :: Value -> Parser [BackendKey (SqlFor a)]

ToHttpApiData (BackendKey (SqlFor a))

Defined in Database.Persist.Typed

Methods

toUrlPiece :: BackendKey (SqlFor a) -> Text

toEncodedUrlPiece :: BackendKey (SqlFor a) -> Builder

toHeader :: BackendKey (SqlFor a) -> ByteString

toQueryParam :: BackendKey (SqlFor a) -> Text

FromHttpApiData (BackendKey (SqlFor a))

Defined in Database.Persist.Typed

Methods

parseUrlPiece :: Text -> Either Text (BackendKey (SqlFor a))

parseHeader :: ByteString -> Either Text (BackendKey (SqlFor a))

parseQueryParam :: Text -> Either Text (BackendKey (SqlFor a))

PathPiece (BackendKey (SqlFor a))

Defined in Database.Persist.Typed

Methods

fromPathPiece :: Text -> Maybe (BackendKey (SqlFor a))

toPathPiece :: BackendKey (SqlFor a) -> Text

PersistFieldSql (BackendKey (SqlFor a))

Defined in Database.Persist.Typed

Methods

sqlType :: Proxy (BackendKey (SqlFor a)) -> SqlType

PersistQueryRead (SqlFor a)

Defined in Database.Persist.Typed

Methods

selectSourceRes :: (PersistRecordBackend record (SqlFor a), MonadIO m1, MonadIO m2) => [Filter record] -> [SelectOpt record] -> ReaderT (SqlFor a) m1 (Acquire (ConduitM () (Entity record) m2 ()))

selectFirst :: (MonadIO m, PersistRecordBackend record (SqlFor a)) => [Filter record] -> [SelectOpt record] -> ReaderT (SqlFor a) m (Maybe (Entity record))

selectKeysRes :: (MonadIO m1, MonadIO m2, PersistRecordBackend record (SqlFor a)) => [Filter record] -> [SelectOpt record] -> ReaderT (SqlFor a) m1 (Acquire (ConduitM () (Key record) m2 ()))

count :: (MonadIO m, PersistRecordBackend record (SqlFor a)) => [Filter record] -> ReaderT (SqlFor a) m Int

PersistQueryWrite (SqlFor db)

Defined in Database.Persist.Typed

Methods

updateWhere :: (MonadIO m, PersistRecordBackend record (SqlFor db)) => [Filter record] -> [Update record] -> ReaderT (SqlFor db) m ()

deleteWhere :: (MonadIO m, PersistRecordBackend record (SqlFor db)) => [Filter record] -> ReaderT (SqlFor db) m ()

PersistUniqueRead (SqlFor a)

Defined in Database.Persist.Typed

Methods

getBy :: (MonadIO m, PersistRecordBackend record (SqlFor a)) => Unique record -> ReaderT (SqlFor a) m (Maybe (Entity record))

PersistUniqueWrite (SqlFor db)

Defined in Database.Persist.Typed

Methods

deleteBy :: (MonadIO m, PersistRecordBackend record (SqlFor db)) => Unique record -> ReaderT (SqlFor db) m ()

insertUnique :: (MonadIO m, PersistRecordBackend record (SqlFor db)) => record -> ReaderT (SqlFor db) m (Maybe (Key record))

upsert :: (MonadIO m, PersistRecordBackend record (SqlFor db), OnlyOneUniqueKey record) => record -> [Update record] -> ReaderT (SqlFor db) m (Entity record)

upsertBy :: (MonadIO m, PersistRecordBackend record (SqlFor db)) => Unique record -> record -> [Update record] -> ReaderT (SqlFor db) m (Entity record)

putMany :: (MonadIO m, PersistRecordBackend record (SqlFor db)) => [record] -> ReaderT (SqlFor db) m ()

HasPersistBackend (SqlFor a)

Defined in Database.Persist.Typed

Associated Types

type BaseBackend (SqlFor a) :: Type

Methods

persistBackend :: SqlFor a -> BaseBackend (SqlFor a)

IsPersistBackend (SqlFor a)

Defined in Database.Persist.Typed

Methods

mkPersistBackend :: BaseBackend (SqlFor a) -> SqlFor a

PersistCore (SqlFor a)

Defined in Database.Persist.Typed

Associated Types

data BackendKey (SqlFor a) :: Type

PersistStoreRead (SqlFor a)

Defined in Database.Persist.Typed

Methods

get :: (MonadIO m, PersistRecordBackend record (SqlFor a)) => Key record -> ReaderT (SqlFor a) m (Maybe record)

getMany :: (MonadIO m, PersistRecordBackend record (SqlFor a)) => [Key record] -> ReaderT (SqlFor a) m (Map (Key record) record)

PersistStoreWrite (SqlFor a)

Defined in Database.Persist.Typed

Methods

insert :: (MonadIO m, PersistRecordBackend record (SqlFor a)) => record -> ReaderT (SqlFor a) m (Key record)

insert_ :: (MonadIO m, PersistRecordBackend record (SqlFor a)) => record -> ReaderT (SqlFor a) m ()

insertMany :: (MonadIO m, PersistRecordBackend record (SqlFor a)) => [record] -> ReaderT (SqlFor a) m [Key record]

insertMany_ :: (MonadIO m, PersistRecordBackend record (SqlFor a)) => [record] -> ReaderT (SqlFor a) m ()

insertEntityMany :: (MonadIO m, PersistRecordBackend record (SqlFor a)) => [Entity record] -> ReaderT (SqlFor a) m ()

insertKey :: (MonadIO m, PersistRecordBackend record (SqlFor a)) => Key record -> record -> ReaderT (SqlFor a) m ()

repsert :: (MonadIO m, PersistRecordBackend record (SqlFor a)) => Key record -> record -> ReaderT (SqlFor a) m ()

repsertMany :: (MonadIO m, PersistRecordBackend record (SqlFor a)) => [(Key record, record)] -> ReaderT (SqlFor a) m ()

replace :: (MonadIO m, PersistRecordBackend record (SqlFor a)) => Key record -> record -> ReaderT (SqlFor a) m ()

delete :: (MonadIO m, PersistRecordBackend record (SqlFor a)) => Key record -> ReaderT (SqlFor a) m ()

update :: (MonadIO m, PersistRecordBackend record (SqlFor a)) => Key record -> [Update record] -> ReaderT (SqlFor a) m ()

updateGet :: (MonadIO m, PersistRecordBackend record (SqlFor a)) => Key record -> [Update record] -> ReaderT (SqlFor a) m record

PersistField (BackendKey (SqlFor a))

Defined in Database.Persist.Typed

Methods

toPersistValue :: BackendKey (SqlFor a) -> PersistValue

fromPersistValue :: PersistValue -> Either Text (BackendKey (SqlFor a))

type BaseBackend (SqlFor a)

Defined in Database.Persist.Typed

type BaseBackend (SqlFor a) = SqlFor a

newtype BackendKey (SqlFor a)

Defined in Database.Persist.Typed

newtype BackendKey (SqlFor a) = SqlForKey {

• unSqlForKey :: BackendKey SqlBackend

}

Specialized aliases

type SqlPersistTFor db = ReaderT (SqlFor db)

This type signature represents a database query for a specific database. You will likely want to specialize this to your own application for readability:

data MainDb

type MainQueryT = SqlPersistTFor MainDb

getStuff :: MonadIO m => StuffId -> MainQueryT m (Maybe Stuff)

Since: 0.0.1.0

type ConnectionPoolFor db = Pool (SqlFor db)

A Pool of database connections that are specialized to a specific database.

Since: 0.0.1.0

type SqlPersistMFor db = ReaderT (SqlFor db) (NoLoggingT (ResourceT IO))

A specialization of SqlPersistM that uses the underlying db database type.

Since: 0.0.1.0

Running specialized queries

runSqlPoolFor :: MonadUnliftIO m => SqlPersistTFor db m a -> ConnectionPoolFor db -> m a

Run a SqlPersistTFor action on an appropriate database.

Since: 0.0.1.0

runSqlConnFor :: MonadUnliftIO m => SqlPersistTFor db m a -> SqlFor db -> m a

Run a SqlPersistTFor action on the appropriate database connection.

Since: 0.0.1.0

Specializing and generalizing

generalizePool :: ConnectionPoolFor db -> ConnectionPool

Generalize a Pool (SqlFor db) to an ordinary ConnectionPool. This renders the pool unusable for model-specific code that relies on the type safety, but allows you to use it for general-purpose SQL queries.

Since: 0.0.1.0

specializePool :: ConnectionPool -> ConnectionPoolFor db

Specialize a ConnectionPool to a Pool (SqlFor db). You should apply this whenever you create or initialize the database connection pooling to avoid potentially mixing the database pools up.

Since: 0.0.1.0

generalizeQuery :: forall db m a. SqlPersistTFor db m a -> SqlPersistT m a

Generalizes a query from a specific database to one that is database agnostic.

Since: 0.0.1.0

specializeQuery :: forall db m a. SqlPersistT m a -> SqlPersistTFor db m a

Specialize a query to a specific database. You should define aliases for this function for each database you use.

data MainDb

data AccountDb

mainQuery :: ReaderT SqlBackend m a -> ReaderT (SqlFor MainDb) m a
mainQuery = specializeQuery

accountQuery :: ReaderT SqlBackend m a -> ReaderT (SqlFor AccountDb) m a
accountQuery = specializeQuery

Since: 0.0.1.0

generalizeSqlBackend :: SqlFor db -> SqlBackend

Generalizes a SqlFor backend to be database agnostic.

Since: 0.0.1.0

specializeSqlBackend :: SqlBackend -> SqlFor db

Specializes a SqlBackend for a specific database.

Since: 0.0.1.0

Key functions

toSqlKeyFor :: ToBackendKey (SqlFor a) record => Int64 -> Key record

Persistent's toSqlKey and fromSqlKey hardcode the SqlBackend, so we have to reimplement them here.

Since: 0.0.1.0

fromSqlKeyFor :: ToBackendKey (SqlFor a) record => Key record -> Int64

Persistent's toSqlKey and fromSqlKey hardcode the SqlBackend, so we have to reimplement them here.

Since: 0.0.1.0