CODEWITHSUNDEEP
haskellhttp-conduitservant
Thibaud Dauce
Thibaud Dauce

Reputation: 377

Get the status code of a webpage in Haskell

I'm trying to find a way to check if a webpage exists in Haskell. The server is HTTP2 / HTTPS only and I'm trying to check if the page exists in a servant application.

Is there any Haskell packages with good documentation to just check if the status code is 200 or 404? And working with strong HTTPS and HTTP2 servers?

Here what I currently have with http-conduit but I'm receiving weird exceptions (TlsExceptionHostPort (HandshakeFailed (Error_Protocol ("expecting server hello, got alert : [(AlertLevel_Fatal,HandshakeFailure)]",True,HandshakeFailure))) "thibaud.dauce.fr" 443 and StatusCodeException).

... other imports
import qualified Network.HTTP.Conduit as HTTP

... other types
type AppM = ReaderT Config (EitherT ServantErr IO)

newComment :: String -> OneComment -> AppM Int64
newComment baseUrl oneComment = do
    time <- liftIO getCurrentTime
    response <- HTTP.withManager $ \manager -> do
        request <- HTTP.parseUrl $ url oneComment
        HTTP.httpLbs request manager
    case (statusIsSuccessful $ HTTP.responseStatus response, startswith baseUrl (url oneComment)) of
        (_, False) -> return 0
        (True, True) -> do
            theNewComment <- runDb $ insert $ Comment (url oneComment) (content oneComment) time
            return $ fromSqlKey theNewComment
        _ -> return 0

Upvotes: 1

Views: 464

Answers (1)

ErikR
ErikR

Reputation: 52029

Some examples using wreq

{-# LANGUAGE OverloadedStrings #-}

import Network.Wreq
import Control.Lens
import Control.Exception as E
import Network.HTTP.Client (HttpException)

test1 = do
  r <- get "https://httpbin.org/get"
  print $ r ^. responseStatus . statusCode

-- throws an exception
test2 = do
  r <- get "https://www.google123123.com"
  print $ r ^. responseStatus . statusCode

testUrl url = do
  r <- get url
  return $ r ^. responseStatus . statusCode

-- catching the exception
test3 = do
  st <- testUrl "https://www.google123123123.com"  `E.catch` handler
  print st
  where
    handler :: HttpException -> IO Int
    handler _ = return 999

Upvotes: 3

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