Per-route content negotiation, and OpenAPI only for root (#693)

* WIP: remove non-openapi root spec

* Refactor ContentType

Different endpoints will favor one type over another

* Permit different Accept headers per endpoint

* Lint

* Add charset to Content-Type only when used as a header

Keep it out of error messages

* Accept: */* is last resort, not first

* Changelog

* makeMimeList consistently

* Remove schema description from OPTIONS response

src/PostgREST/Middleware.hs

@@ -8,20 +8,17 @@ import qualified Data.HashMap.Strict           as M
 import           Data.String.Conversions       (cs)
 import qualified Hasql.Transaction             as H
 
-import           Network.HTTP.Types.Header     (hAccept)
-import           Network.HTTP.Types.Status     (status400, status415)
-import           Network.Wai                   (Application, Request (..),
-                                                Response, requestHeaders)
+import           Network.HTTP.Types.Status     (status400)
+import           Network.Wai                   (Application, Response)
 import           Network.Wai.Middleware.Cors   (cors)
 import           Network.Wai.Middleware.Gzip   (def, gzip)
 import           Network.Wai.Middleware.Static (only, staticPolicy)
 
-import           PostgREST.ApiRequest          (ApiRequest(..), ContentType(..), pickContentType)
+import           PostgREST.ApiRequest          (ApiRequest(..))
 import           PostgREST.Auth                (claimsToSQL)
 import           PostgREST.Config              (AppConfig (..), corsPolicy)
 import           PostgREST.Error               (errResponse)
 import           Data.Text
-import           Data.List (lookup)
 
 import           Protolude                     hiding (concat, null)
 
@@ -39,20 +36,8 @@ runWithClaims conf eClaims app req =
     anon = String . cs $ configAnonRole conf
     clientErr = return . errResponse status400
 
-unsupportedAccept :: Application -> Application
-unsupportedAccept app req respond =
-  case (isTargetRoot, accept) of
-    (_, Left _) -> unsupportedAcceptRespond
-    (False, Right OpenAPI) -> unsupportedAcceptRespond
-    (_, Right _) -> app req respond
-  where accept = pickContentType $ lookup hAccept $ requestHeaders req
-        path = pathInfo req
-        isTargetRoot = fromMaybe True $ (== "") <$> listToMaybe path
-        unsupportedAcceptRespond = respond $ errResponse status415 "Unsupported Accept header, try: application/json"
-
 defaultMiddle :: Application -> Application
 defaultMiddle =
     gzip def
   . cors corsPolicy
   . staticPolicy (only [("favicon.ico", "static/favicon.ico")])
-  . unsupportedAccept