Created
March 20, 2017 06:10
-
-
Save naoto-ogawa/3c9f5147e2c0e78503408700cbe4b166 to your computer and use it in GitHub Desktop.
Servant CSV download sample
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
{-# LANGUAGE DataKinds #-} | |
{-# LANGUAGE DeriveGeneric #-} | |
{-# LANGUAGE FlexibleInstances #-} | |
{-# LANGUAGE GeneralizedNewtypeDeriving #-} | |
{-# LANGUAGE MultiParamTypeClasses #-} | |
{-# LANGUAGE OverloadedStrings #-} | |
{-# LANGUAGE ScopedTypeVariables #-} | |
{-# LANGUAGE TypeOperators #-} | |
import Control.Monad.IO.Class -- liftIO | |
import Control.Monad.Trans.Except -- Handler | |
import Data.Aeson.Types -- JSON | |
import Data.Aeson.Parser -- JSON | |
import GHC.Generics | |
import Network.Wai.Handler.Warp | |
import Servant | |
import qualified Network.HTTP.Media as M | |
import Text.CSV | |
import qualified Data.ByteString.Lazy.Char8 as C | |
type MyAPI = "csv" :> Capture "file" String :> Get '[CSV'] CSV | |
data CSV' | |
instance Accept CSV' where | |
contentType _ = "application" M.// "csv" | |
instance MimeRender CSV' CSV where | |
mimeRender _ val = C.pack $ printCSV val | |
csv' :: String -> Handler CSV | |
csv' f = do | |
ret <- liftIO $ parseCSVFromFile ("./data/" ++ f ++ ".csv") | |
case ret of | |
Left l -> throwError err400 {errBody="parse error"} | |
Right r -> return r | |
myServer :: Server MyAPI | |
myServer = csv' | |
myProxy :: Proxy MyAPI | |
myProxy = Proxy | |
myApp :: Application | |
myApp = serve myProxy myServer | |
main :: IO () | |
main = run 8081 myApp | |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment