servant/servant-js/test/Servant/JSSpec/CustomHeaders.hs

59 lines
2.2 KiB
Haskell

{-# LANGUAGE DataKinds #-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE KindSignatures #-}
{-# LANGUAGE PolyKinds #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE TypeOperators #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE MultiParamTypeClasses #-}
module Servant.JSSpec.CustomHeaders where
import Control.Lens
import Data.Monoid
import Data.Proxy
import Data.Text (pack)
import GHC.TypeLits
import Servant.JS.Internal
-- | This is a hypothetical combinator that fetches an Authorization header.
-- The symbol in the header denotes what kind of authentication we are
-- using -- Basic, Digest, whatever.
data Authorization (sym :: Symbol) a
instance (KnownSymbol sym, HasForeign lang () api)
=> HasForeign lang () (Authorization sym a :> api) where
type Foreign () (Authorization sym a :> api) = Foreign () api
foreignFor lang ftype Proxy req = foreignFor lang ftype (Proxy :: Proxy api) $
req & reqHeaders <>~
[ ReplaceHeaderArg (Arg "Authorization" ())
$ tokenType (pack . symbolVal $ (Proxy :: Proxy sym)) ]
where
tokenType t = t <> " {Authorization}"
-- | This is a combinator that fetches an X-MyLovelyHorse header.
data MyLovelyHorse a
instance (HasForeign lang () api)
=> HasForeign lang () (MyLovelyHorse a :> api) where
type Foreign () (MyLovelyHorse a :> api) = Foreign () api
foreignFor lang ftype Proxy req = foreignFor lang ftype (Proxy :: Proxy api) $
req & reqHeaders <>~ [ ReplaceHeaderArg (Arg "X-MyLovelyHorse" ()) tpl ]
where
tpl = "I am good friends with {X-MyLovelyHorse}"
-- | This is a combinator that fetches an X-WhatsForDinner header.
data WhatsForDinner a
instance (HasForeign lang () api)
=> HasForeign lang () (WhatsForDinner a :> api) where
type Foreign () (WhatsForDinner a :> api) = Foreign () api
foreignFor lang ftype Proxy req = foreignFor lang ftype (Proxy :: Proxy api) $
req & reqHeaders <>~ [ ReplaceHeaderArg (Arg "X-WhatsForDinner" ()) tpl ]
where
tpl = "I would like {X-WhatsForDinner} with a cherry on top."