CODEWITHSUNDEEP
haskellhttp-conduit
user266003
user266003

Reputation:

Unable to append a header to a request

I need to add a header and send a request:

 import Network.HTTP.Conduit
 import qualified Data.ByteString.Char8 as C8

 --..........
 res <- withManager $ httpLbs $ createReq request
  return ()
    where
      createReq r = r {
        --...........
        requestHeaders = ("content-type", "application/json") : requestHeaders r
      }

I've got 2 errors:

   Couldn't match type `[Char]'
                  with `case-insensitive-1.0.0.1:Data.CaseInsensitive.CI
                          C8.ByteString'
    Expected type: HeaderName
      Actual type: [Char]
    In the expression: "content-type"
    In the first argument of `(:)', namely
      `("content-type", "application/json")'
    In the `requestHeaders' field of a record


    Couldn't match expected type `C8.ByteString'
                with actual type `[Char]'
    In the expression: "application/json"
    In the first argument of `(:)', namely
      `("content-type", "application/json")'

How do I solve them?

UPDATE: C8.pack doesn't, it causes other errors.

Upvotes: 0

Views: 186

Answers (1)

Nikita Volkov
Nikita Volkov

Reputation: 43309

As the error suggests, the compiler expects a type Data.CaseInsensitive.CI C8.ByteString, while you provide it with [Char] (aka String).

I suspect your problem is caused by the missing OverloadedStrings extension, which enables arbitrary types to be constructed from string literals. To fix this add the following line in the beginning of your module:

{-# LANGUAGE OverloadedStrings #-}

Upvotes: 3

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