haskell - Building a query string for a get request

Question

Suppose I have this function performing a get request:

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

get :: String -> [(C8.ByteString, C8.ByteString)] -> IO (Response LC8.ByteString)
get url par = do
  request <- parseUrl url 
  res <- withManager $ httpLbs $ createReq request
  return res
  where
    createReq req = 
      req {
            method = methodGet
          , queryString = map (\(k, v) -> k ++ "&=" ++ v) par -- ????
          }

I believe there must a simpler way to create a query string. My method both is not simple and wrong as it doesn't care about "?" and "&" (there must be "?" in the beggining and must not be "&" at the end). So how do I create a query string for a get request from [(C8.ByteString, C8.ByteString)] ? Moreover, (++) can't be used with ByteString. But I haven't found any example which is surprising.

Answer 1

使用包中存在的Network.HTTP.Types.URI中的函数。http-types事实上，http-types是http-conduit.

λ> import Network.HTTP.Types.URI
λ> import Data.ByteString
λ> :set -XOverloadedStrings
λ> let getData = [("key1", Just "value1"), ("key2", Just "value2")] :: [(ByteString, Maybe ByteString)]
λ> renderQuery True getData
"?key1=value1&key2=value2"
λ> renderQuery False getData
"key1=value1&key2=value2"

了解如何控制请求前的Bool值。renderQuery?

更新：从 开始http-client 0.3.6，Michael Snoyman在setQueryString中添加了这个功能，正如他在评论中所指出的那样。