persistent-postgresq example

persistent-postgresql.hs

{-# LANGUAGE OverloadedStrings #-}

import Types

import Database.Persist.Postgresql
import Control.Monad.Logger
import Control.Monad.IO.Class

printIO :: (MonadIO m, Show a) => a -> m ()
printIO = liftIO . print

createGame :: MonadIO m => BoardGame -> SqlPersistT m (Entity BoardGame) 
createGame = insertEntity

readGame :: MonadIO m => Int -> SqlPersistT m (Maybe BoardGame) 
readGame = get . toSqlKey . fromIntegral

main :: IO ()
main = 
    runStdoutLoggingT
        . withPostgresqlPool "host=localhost port=5432 connect_timeout=10" 3
        . runSqlPool
        $ do
            result <- createGame $ BoardGame
                "Cosmic Encounter"
                "Bill Eberle"
                (Just 2008)
            liftIO $ print result

            -- This is the easiest way to re-read a record:
            get (entityKey result) >>= printIO 

            -- Getting by id
            readGame 1 >>= printIO 
            
            -- Get by name too:
            getBy (UniqueName "Cosmic Encounter") >>= printIO