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We also recommend that a + file or class name and description of purpose be included on the + same "printed page" as the copyright notice for easier + identification within third-party archives. + + Copyright [yyyy] [name of copyright owner] + + Licensed under the Apache License, Version 2.0 (the "License"); + you may not use this file except in compliance with the License. + You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, software + distributed under the License is distributed on an "AS IS" BASIS, + WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + See the License for the specific language governing permissions and + limitations under the License. diff --git a/Setup.hs b/Setup.hs new file mode 100644 --- /dev/null +++ b/Setup.hs @@ -0,0 +1,2 @@ +import Distribution.Simple +main = defaultMain diff --git a/src/Versioning/Servant.hs b/src/Versioning/Servant.hs new file mode 100644 --- /dev/null +++ b/src/Versioning/Servant.hs @@ -0,0 +1,91 @@ +{-# LANGUAGE AllowAmbiguousTypes #-} +{-# LANGUAGE DataKinds #-} +{-# LANGUAGE DeriveDataTypeable #-} +{-# LANGUAGE FlexibleContexts #-} +{-# LANGUAGE FlexibleInstances #-} +{-# LANGUAGE KindSignatures #-} +{-# LANGUAGE MultiParamTypeClasses #-} +{-# LANGUAGE OverloadedStrings #-} +{-# LANGUAGE ScopedTypeVariables #-} +{-# LANGUAGE TypeApplications #-} +{-# LANGUAGE UndecidableInstances #-} +module Versioning.Servant + ( VersionedJSON + , VersionedJSONFrom + ) +where + +import Data.Aeson (FromJSON, ToJSON, encode, + parseJSON) +import Data.Aeson.Parser (value) +import Data.Aeson.Types (parseEither) +import Data.Attoparsec.ByteString.Char8 (endOfInput, parseOnly, + skipSpace, ()) +import qualified Data.ByteString.Lazy as LazyBS +import Data.Kind (Type) +import qualified Data.List.NonEmpty as NonEmpty +import Data.Typeable (Typeable) +import qualified Network.HTTP.Media as Media +import Servant.API (Accept (..), MimeRender (..), + MimeUnrender (..)) + +import Versioning.Base +import Versioning.Internal.Decoding +import Versioning.JSON + +-- | Drop-in replacement for the 'JSON' data-type +-- for seamless integration with servant. +type VersionedJSON = VersionedJSONFrom V0 + +-- | Like 'VersionedJSON', with an additional type-parameter +-- indicating the oldest version you want to be able to decode +data VersionedJSONFrom (v :: V) deriving Typeable + +instance Accept (VersionedJSONFrom from) where + contentTypes _ = + "application" Media.// "json" Media./: ("charset", "utf-8") NonEmpty.:| + [ "application" Media.// "json" ] + +-- We add a redundant 'JsonDecodableTo' constraint to minimize the risk +-- of using the 'VersionedJSON' type in the wrong place +instance {-# OVERLAPPABLE #-} (JsonDecodableToFrom from v a, ToJSON (a v)) + => MimeRender (VersionedJSONFrom from) (a v) where + mimeRender _ = encode + +instance JsonDecodableToFrom from v a => MimeUnrender (VersionedJSONFrom from) (a v) where + mimeUnrender _ = fromJsonAnyVersionLenientFrom @from + +-- | Like 'fromJsonAnyVersionEither', but it uses 'eitherDecodeLenient' for decoding +fromJsonAnyVersionLenientFrom + :: forall from v a + . JsonDecodableToFrom from v a + => LazyBS.ByteString + -> Either String (a v) +fromJsonAnyVersionLenientFrom = decodeAnyVersionFrom @from jsonDecodeLenient + +-- | Lenient JSON decoder +jsonDecodeLenient + :: Decoder FromJSON LazyBS.ByteString (Either String) (a :: V -> Type) +jsonDecodeLenient = Decoder eitherDecodeLenient + +-- Copied and pasted from Servant.API.ContentTypes: + +-- | Like 'Data.Aeson.eitherDecode' but allows all JSON values instead of just +-- objects and arrays. +-- +-- Will handle trailing whitespace, but not trailing junk. ie. +-- +-- >>> eitherDecodeLenient "1 " :: Either String Int +-- Right 1 +-- +-- >>> eitherDecodeLenient "1 junk" :: Either String Int +-- Left "trailing junk after valid JSON: endOfInput" +eitherDecodeLenient :: FromJSON a => LazyBS.ByteString -> Either String a +eitherDecodeLenient input = parseOnly parser (LazyBS.toStrict input) + >>= parseEither parseJSON + where + parser = + skipSpace + *> value + <* skipSpace + <* (endOfInput "trailing junk after valid JSON") diff --git a/tests/Main.hs b/tests/Main.hs new file mode 100644 --- /dev/null +++ b/tests/Main.hs @@ -0,0 +1,26 @@ +{-# LANGUAGE OverloadedStrings #-} +{-# LANGUAGE TypeApplications #-} +module Main where + +import Data.Aeson +import Data.Maybe (fromJust) +import Network.Wai.Test (SResponse (simpleBody)) +import Test.Hspec +import Test.Hspec.Wai + +import Tests.Versioning.Servant.Fixtures +import Versioning.Base + +main :: IO () +main = hspec $ with (pure app) $ do + let headers = [("Content-Type", "application/json")] + decodeV2 = fromJust . decode @(Foo V2) + + describe "VersionedJSON" $ do + it "given the latest version returns latest version" $ do + res <- request "POST" "foo" headers fooJsonV2 + liftIO $ decodeV2 (simpleBody res) `shouldBe` decodeV2 fooJsonV2 + + it "given a previous version returns latest version" $ do + res <- request "POST" "foo" headers fooJsonV0 + liftIO $ decodeV2 (simpleBody res) `shouldBe` decodeV2 fooJsonV2 diff --git a/tests/Tests/Versioning/Servant/Fixtures.hs b/tests/Tests/Versioning/Servant/Fixtures.hs new file mode 100644 --- /dev/null +++ b/tests/Tests/Versioning/Servant/Fixtures.hs @@ -0,0 +1,100 @@ +{-# LANGUAGE DataKinds #-} +{-# LANGUAGE DeriveGeneric #-} +{-# LANGUAGE FlexibleContexts #-} +{-# LANGUAGE FlexibleInstances #-} +{-# LANGUAGE KindSignatures #-} +{-# LANGUAGE MultiParamTypeClasses #-} +{-# LANGUAGE OverloadedStrings #-} +{-# LANGUAGE StandaloneDeriving #-} +{-# LANGUAGE TypeApplications #-} +{-# LANGUAGE TypeFamilies #-} +{-# LANGUAGE TypeOperators #-} +{-# LANGUAGE TypeSynonymInstances #-} +{-# LANGUAGE UndecidableInstances #-} +module Tests.Versioning.Servant.Fixtures where + +import Data.Aeson +import qualified Data.ByteString.Lazy as LazyBS +import GHC.Generics (Generic) +import Network.Wai (Application) +import Servant + +import Versioning.Base +import Versioning.JSON +import Versioning.Servant (VersionedJSON) +import Versioning.Upgrade + +type Api = "foo" :> ReqBody '[VersionedJSON] (Foo V2) :> Post '[JSON] (Foo V2) + +server :: Server Api +server = pure + +app :: Application +app = serve (Proxy :: Proxy Api) server + +data Foo v = Foo + { always :: Int -- this field exists in all versions + , sinceV1 :: Since V1 v Bool -- this field has been introduced in V1 + , sinceV2 :: Since V2 v String -- this field has been introduced in V2 + , untilV1 :: Until V1 v Double -- this field has been removed in V2 + } deriving (Generic) + +deriving instance Eq (Foo V0) + +deriving instance Eq (Foo V1) + +deriving instance Eq (Foo V2) + +instance FromJSON (Foo V0) + +instance FromJSON (Foo V1) + +instance FromJSON (Foo V2) + +deriving instance Show (Foo V0) + +deriving instance Show (Foo V1) + +deriving instance Show (Foo V2) + +instance ToJSON (Foo V2) + +-- How to upcast from V1 to V2 +instance Adapt V0 V1 Foo where + adapt foo = foo { sinceV1 = True + , sinceV2 = na + , untilV1 = untilV1 foo + } + +-- How to upcast from V2 to V3 +instance Adapt V1 V2 Foo where + adapt foo = foo { sinceV1 = sinceV1 foo + , sinceV2 = "hello" + , untilV1 = na + } + +type instance Applied Show a = String + +-- | A 'Foo' at version V0 +foo0 :: Foo V0 +foo0 = Foo + { always = 1 + , sinceV1 = na + , sinceV2 = na + , untilV1 = 3.14 + } + +-- | A 'Foo' at version V2 +foo2 :: Foo V2 +foo2 = Foo + { always = 1 + , sinceV1 = True + , sinceV2 = "hello" + , untilV1 = Nothing + } + +fooJsonV0 :: LazyBS.ByteString +fooJsonV0 = "{\"always\":1, \"untilV1\": 3.14}" + +fooJsonV2 :: LazyBS.ByteString +fooJsonV2 = "{\"always\":1, \"sinceV1\": true, \"sinceV2\": \"hello\"}" diff --git a/versioning-servant.cabal b/versioning-servant.cabal new file mode 100644 --- /dev/null +++ b/versioning-servant.cabal @@ -0,0 +1,47 @@ +name: versioning-servant +version: 0.1.0.0 +synopsis: Servant combinators for the versioning library. +description: This package provides Servant combinators to be used with + the 'versioning' library. +homepage: https://github.com/lortabac/versioning +license: Apache-2.0 +license-file: LICENSE +author: Lorenzo Tabacchini +maintainer: lortabac@gmx.com +copyright: (c) 2018 Lorenzo Tabacchini +category: Data +build-type: Simple +extra-source-files: ChangeLog.md +cabal-version: >=1.10 + +library + exposed-modules: Versioning.Servant + build-depends: base >=4.10 && <4.12 + , aeson >=1.0 && <1.5 + , attoparsec + , bytestring >=0.10 && <0.11 + , http-media + , servant + , versioning >=0.2 + hs-source-dirs: src + default-language: Haskell2010 + ghc-options: -Wall + +test-suite tests + type: exitcode-stdio-1.0 + main-is: Main.hs + other-modules: Tests.Versioning.Servant.Fixtures + build-depends: base >=4.10 && <4.12 + , aeson >=1.0 && <1.5 + , bytestring >=0.10 && <0.11 + , hspec >=2.0 && <2.6 + , hspec-wai >=0.9 + , servant + , servant-server + , versioning + , versioning-servant + , wai + , wai-extra + hs-source-dirs: tests + default-language: Haskell2010 + ghc-options: -Wall