Portability | Not portable |
---|---|
Safe Haskell | None |
Language | Haskell2010 |
Quick start
Automatic derive of typed DB API based on postgresql-query package.
How to use:
- Define your instances of
MonadLogger
andHasPostgres
for your app monad:
newtype PostgresM a = PostgresM { runPostgresM :: PgMonadT (LoggingT IO) a } deriving (Functor, HasPostgres, MonadLogger, Monad, Applicative, MonadBase IO)
- Define type level API:
type UserId = Int data RegisterUser = RegisterUser { userRegName :: String , userRegPassword :: String , userRegRegTime :: Day } deriving (Eq) deriveToRow ''RegisterUser data User = User { userId :: UserId , userName :: String , userPassword :: String , userRegTime :: Day } deriving (Eq) deriveFromRow ''User deriveToRow ''User type UserAPI = ArgNamed "u" (Composite RegisterUser) :> Procedure "postUser" (Only Int) :<|> ArgPos Int :> Procedure "getUser" (Maybe User) :<|> ArgPos Int :> Procedure "deleteUser" () :<|> Procedure "getUsers" [User]
- Derive client functions from the API:
postUser :: Composite RegisterUser -> PostgresM (Only Int) getUser :: Int -> PostgresM (Maybe User) deleteUser :: Int -> PostgresM () getUsers :: PostgresM [User] ( postUser :<|> getUser :<|> deleteUser :<|> getUsers) = deriveDB (Proxy :: Proxy UserAPI) (Proxy :: Proxy PostgresM)
Features
- Call functions in schema with
:>
operator:
type API = "test" :> ArgPos Int :> Procedure "square" (Only Int)
That will call function `test.square(int)`.
- Composite types are defined with `Composite a` wrapper:
type API = ArgNamed "u" (Composite UserCreate) :> Procedure "postUser" (Only Int)
- Support for arrays:
type API = ArgPos (PGArray Int) :> Procedure "mleast" (Maybe (Only Int))
- Support for variadic arguments:
type API = ArgPos (Variadic Int) :> Procedure "mleast" (Maybe (Only Int))
- Support for default arguments with
Default
wrapper:
type API = ArgPos (Default Int) :> Procedure "foo" (Only Int)
Support for composite types
Support for variadic types
Deriving of DB clients
module Servant.DB.PostgreSQL.HasDB