9be8693475
This commit introduces a new type-level combinator, `WithRoutingHeader`.
It modifies the behaviour of the following sub-API, such that all endpoint
of said API return an additional routing header in their response.
A routing header is a header that specifies which endpoint the
incoming request was routed to.
Endpoint are designated by their path, in which `Capture'` and
`CaptureAll` combinators are replaced by a capture hint.
This header can be used by downstream middlewares to gather
information about individual endpoints, since in most cases
a routing header uniquely identifies a single endpoint.
Example:
```haskell
type MyApi =
WithRoutingHeader :> "by-id" :> Capture "id" Int :> Get '[JSON] Foo
-- GET /by-id/1234 will return a response with the following header:
-- ("Servant-Routed-Path", "/by-id/<id::Int>")
```
To achieve this, two refactorings were necessary:
* Introduce a type `RouterEnv env` to encapsulate the `env` type
(as in `Router env a`), which contains a tuple-encoded list of url
pieces parsed from the incoming request.
This type makes it possible to pass more information throughout the
routing process, and the computation of the `Delayed env c` associated
with each request.
* Introduce a new kind of router, which only modifies the RouterEnv, and
doesn't affect the routing process otherwise.
`EnvRouter (RouterEnv env -> RouterEnv env) (Router' env a)`
This new router is used when encountering the `WithRoutingHeader`
combinator in an API, to notify the endpoints of the sub-API that they
must produce a routing header (this behaviour is disabled by default).
152 lines
5.2 KiB
Haskell
152 lines
5.2 KiB
Haskell
{-# LANGUAGE DataKinds #-}
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{-# LANGUAGE FlexibleInstances #-}
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{-# LANGUAGE KindSignatures #-}
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{-# LANGUAGE MultiParamTypeClasses #-}
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{-# LANGUAGE OverloadedStrings #-}
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{-# LANGUAGE ScopedTypeVariables #-}
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{-# LANGUAGE TypeFamilies #-}
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{-# LANGUAGE TypeOperators #-}
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module Servant.Server.Internal.RoutingApplicationSpec (spec) where
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import Prelude ()
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import Prelude.Compat
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import Control.Exception hiding
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(Handler)
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import Control.Monad.IO.Class
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import Control.Monad.Trans.Resource
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(register)
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import Data.IORef
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import Data.Proxy
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import GHC.TypeLits
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(KnownSymbol, Symbol, symbolVal)
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import Network.Wai
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(defaultRequest)
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import Servant
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import Servant.Server.Internal
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import Test.Hspec
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import Test.Hspec.Wai
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(request, shouldRespondWith, with)
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import qualified Data.Text as T
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import System.IO.Unsafe
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(unsafePerformIO)
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data TestResource x
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= TestResourceNone
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| TestResource x
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| TestResourceFreed
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| TestResourceError
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deriving (Eq, Show)
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-- Let's not write to the filesystem
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delayedTestRef :: IORef (TestResource String)
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delayedTestRef = unsafePerformIO $ newIORef TestResourceNone
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fromTestResource :: a -> (b -> a) -> TestResource b -> a
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fromTestResource _ f (TestResource x) = f x
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fromTestResource x _ _ = x
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initTestResource :: IO ()
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initTestResource = writeIORef delayedTestRef TestResourceNone
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writeTestResource :: String -> IO ()
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writeTestResource x = modifyIORef delayedTestRef $ \r -> case r of
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TestResourceNone -> TestResource x
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_ -> TestResourceError
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freeTestResource :: IO ()
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freeTestResource = modifyIORef delayedTestRef $ \r -> case r of
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TestResource _ -> TestResourceFreed
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_ -> TestResourceError
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delayed :: DelayedIO () -> RouteResult (Handler ()) -> Delayed () (Handler ())
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delayed body srv = Delayed
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{ capturesD = \() -> return ()
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, methodD = return ()
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, authD = return ()
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, acceptD = return ()
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, contentD = return ()
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, paramsD = return ()
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, headersD = return ()
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, bodyD = \() -> do
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liftIO (writeTestResource "hia" >> putStrLn "garbage created")
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_ <- register (freeTestResource >> putStrLn "garbage collected")
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body
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, serverD = \() () () () _body _req -> srv
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}
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simpleRun :: Delayed () (Handler ())
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-> IO ()
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simpleRun d = fmap (either ignoreE id) . try $
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runAction d (emptyEnv ()) defaultRequest (\_ -> return ()) (\_ -> FailFatal err500)
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where ignoreE :: SomeException -> ()
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ignoreE = const ()
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-------------------------------------------------------------------------------
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-- Combinator example
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-------------------------------------------------------------------------------
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-- | This data types writes 'sym' to 'delayedTestRef'.
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data Res (sym :: Symbol)
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instance (KnownSymbol sym, HasServer api ctx) => HasServer (Res sym :> api) ctx where
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type ServerT (Res sym :> api) m = IORef (TestResource String) -> ServerT api m
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hoistServerWithContext _ nc nt s = hoistServerWithContext (Proxy :: Proxy api) nc nt . s
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route Proxy ctx server = route (Proxy :: Proxy api) ctx $
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addBodyCheck server (return ()) check
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where
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sym = symbolVal (Proxy :: Proxy sym)
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check () = do
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liftIO $ writeTestResource sym
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_ <- register freeTestResource
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return delayedTestRef
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type ResApi = "foobar" :> Res "foobar" :> Get '[PlainText] T.Text
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resApi :: Proxy ResApi
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resApi = Proxy
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resServer :: Server ResApi
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resServer ref = liftIO $ fmap (fromTestResource "<wrong>" T.pack) $ readIORef ref
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-------------------------------------------------------------------------------
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-- Spec
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-------------------------------------------------------------------------------
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spec :: Spec
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spec = do
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describe "Delayed" $ do
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it "actually runs clean up actions" $ do
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liftIO initTestResource
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_ <- simpleRun $ delayed (return ()) (Route $ return ())
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res <- readIORef delayedTestRef
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res `shouldBe` TestResourceFreed
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it "even with exceptions in serverD" $ do
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liftIO initTestResource
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_ <- simpleRun $ delayed (return ()) (Route $ throw DivideByZero)
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res <- readIORef delayedTestRef
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res `shouldBe` TestResourceFreed
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it "even with routing failure in bodyD" $ do
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liftIO initTestResource
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_ <- simpleRun $ delayed (delayedFailFatal err500) (Route $ return ())
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res <- readIORef delayedTestRef
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res `shouldBe` TestResourceFreed
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it "even with exceptions in bodyD" $ do
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liftIO initTestResource
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_ <- simpleRun $ delayed (liftIO $ throwIO DivideByZero) (Route $ return ())
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res <- readIORef delayedTestRef
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res `shouldBe` TestResourceFreed
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describe "ResApi" $
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with (return $ serve resApi resServer) $ do
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it "writes and cleanups resources" $ do
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liftIO initTestResource
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request "GET" "foobar" [] "" `shouldRespondWith` "foobar"
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liftIO $ do
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res <- readIORef delayedTestRef
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res `shouldBe` TestResourceFreed
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