Fixed excess quotes put around plain text responses when using StandaloneLambda.

Author: dnikolovv

aws-lambda-haskell-runtime.cabal

@@ -4,7 +4,7 @@ cabal-version: 1.12
 --
 -- see: https://github.com/sol/hpack
 --
--- hash: c27e1b0a071f3c0ebc02eac12fbefd43b148464edc8f7a6f3fada3d17051bacc
+-- hash: c21b3c988844f7c4bfb806aff4e307c5d5dc63a7973eff4a83eb329e7bccb1c9
 
 name:           aws-lambda-haskell-runtime
 version:        3.0.0
@@ -46,6 +46,7 @@ library
       Aws.Lambda.Runtime.Environment
       Aws.Lambda.Runtime.Error
       Aws.Lambda.Runtime.Publish
+      Aws.Lambda.Utilities
       Paths_aws_lambda_haskell_runtime
   hs-source-dirs:
       src

src/Aws/Lambda/Configuration.hs

@@ -3,7 +3,6 @@ module Aws.Lambda.Configuration
   ( Main.LambdaOptions(..)
   , generateLambdaDispatcher
   , Dispatch.decodeObj
-  , Dispatch.encodeObj
   )
 where
 

src/Aws/Lambda/Meta/Dispatch.hs

@@ -4,7 +4,6 @@
 module Aws.Lambda.Meta.Dispatch
   ( generate
   , decodeObj
-  , encodeObj
   , Runtime.LambdaResult(..)
   ) where
 
@@ -20,6 +19,7 @@ import qualified Language.Haskell.TH as Meta
 import Aws.Lambda.Meta.Common
 import qualified Aws.Lambda.Meta.Main as Main
 import qualified Aws.Lambda.Runtime.ApiGatewayInfo as ApiGatewayInfo
+import Aws.Lambda.Runtime.Common (toStandaloneLambdaResponse)
 import qualified Aws.Lambda.Runtime.Common as Runtime
 import qualified Aws.Lambda.Runtime.Error as Error
 import qualified Control.Exception as Unchecked
@@ -36,13 +36,6 @@ decodeObj x =
     Left e  -> Left $ Error.Parsing e (LazyByteString.unpack x) objName
     Right v -> return v
 
-{-| Helper function that the dispatcher will use to
-decode the JSON that comes as an AWS Lambda event into the
-appropriate type expected by the handler.
--}
-encodeObj :: ToJSON a => a -> String
-encodeObj x = LazyByteString.unpack (encode x)
-
 {-| Generates the dispatcher out of a list of
 handler names in the form @src/Foo/Bar.handler@
 
@@ -70,16 +63,16 @@ standaloneLambdaHandlerCase lambdaHandler = do
     case decodeObj $(expressionName "eventObject") of
       Right eventObject -> (do
           result <- $(expressionName (qualifiedHandlerName lambdaHandler)) eventObject contextObject
-          either (pure . Left . Runtime.StandaloneLambdaError . encodeObj) (pure . Right . Runtime.StandaloneLambdaResult . encodeObj) result)
-          `Unchecked.catch` \(handlerError :: Unchecked.SomeException) -> pure . Left . Runtime.StandaloneLambdaError . encodeObj . show $ handlerError
-      Left err -> pure . Left . Runtime.StandaloneLambdaError . encodeObj $ err|]
+          either (pure . Left . Runtime.StandaloneLambdaError . toStandaloneLambdaResponse) (pure . Right . Runtime.StandaloneLambdaResult . toStandaloneLambdaResponse) result)
+          `Unchecked.catch` \(handlerError :: Unchecked.SomeException) -> pure . Left . Runtime.StandaloneLambdaError . toStandaloneLambdaResponse . show $ handlerError
+      Left err -> pure . Left . Runtime.StandaloneLambdaError . toStandaloneLambdaResponse $ err|]
   pure $ Meta.Match pat (Meta.NormalB body) []
 
 standaloneLambdaUnmatchedCase :: Meta.MatchQ
 standaloneLambdaUnmatchedCase = do
   let pattern = Meta.WildP
   body <- [e|
-    pure . Left . Runtime.StandaloneLambdaError . encodeObj $ ("Handler " <> $(expressionName "functionHandler") <> " does not exist on project")
+    pure . Left . Runtime.StandaloneLambdaError . toStandaloneLambdaResponse $ ("Handler " <> $(expressionName "functionHandler") <> " does not exist on project" :: String)
     |]
   pure $ Meta.Match pattern (Meta.NormalB body) []
 

src/Aws/Lambda/Runtime/ApiGatewayInfo.hs

@@ -14,10 +14,10 @@ module Aws.Lambda.Runtime.ApiGatewayInfo
   , ToApiGatewayResponseBody(..)
   , mkApiGatewayResponse ) where
 
+import Aws.Lambda.Utilities
 import Data.Aeson
 import Data.Aeson.Types (Parser)
 import qualified Data.Aeson.Types as T
-import qualified Data.ByteString.Lazy.Char8 as LazyByteString
 import qualified Data.CaseInsensitive as CI
 import Data.HashMap.Strict (HashMap)
 import Data.Text (Text)
@@ -189,6 +189,3 @@ headerToPair (cibyte, bstr) = k .= v
  where
   k = (T.decodeUtf8 . CI.original) cibyte
   v = T.decodeUtf8 bstr
-
-toJSONText :: ToJSON a => a -> Text
-toJSONText = T.pack . LazyByteString.unpack . encode

src/Aws/Lambda/Runtime/Common.hs

@@ -1,4 +1,8 @@
-{-# LANGUAGE DeriveLift #-}
+{-# LANGUAGE DeriveLift                 #-}
+{-# LANGUAGE DerivingStrategies         #-}
+{-# LANGUAGE FlexibleInstances          #-}
+{-# LANGUAGE GeneralizedNewtypeDeriving #-}
+{-# LANGUAGE UndecidableInstances       #-}
 
 module Aws.Lambda.Runtime.Common
   ( RunCallback
@@ -8,12 +12,18 @@ module Aws.Lambda.Runtime.Common
   , DispatcherOptions(..)
   , ApiGatewayDispatcherOptions(..)
   , DispatcherStrategy(..)
+  , ToLambdaResponseBody(..)
+  , unLambdaResponseBody
   , defaultDispatcherOptions
   ) where
 
 import Aws.Lambda.Runtime.ApiGatewayInfo
 import Aws.Lambda.Runtime.Context (Context)
+import Aws.Lambda.Utilities
+import Data.Aeson (FromJSON, ToJSON)
 import qualified Data.ByteString.Lazy as Lazy
+import Data.Text (Text)
+import qualified Data.Text as Text
 import GHC.Generics (Generic)
 import Language.Haskell.TH.Syntax (Lift)
 
@@ -42,14 +52,33 @@ data DispatcherStrategy =
 type RunCallback context =
   LambdaOptions context -> IO (Either LambdaError LambdaResult)
 
+-- | Wrapper type for lambda response body
+newtype LambdaResponseBody =
+  LambdaResponseBody { unLambdaResponseBody :: Text }
+  deriving newtype (ToJSON, FromJSON)
+
+class ToLambdaResponseBody a where
+  toStandaloneLambdaResponse :: a -> LambdaResponseBody
+
+-- We need to special case String and Text to avoid unneeded encoding
+-- which results in extra quotes put around plain text responses
+instance {-# OVERLAPPING #-} ToLambdaResponseBody String where
+  toStandaloneLambdaResponse = LambdaResponseBody . Text.pack
+
+instance {-# OVERLAPPING #-} ToLambdaResponseBody Text where
+  toStandaloneLambdaResponse = LambdaResponseBody
+
+instance ToJSON a => ToLambdaResponseBody a where
+  toStandaloneLambdaResponse = LambdaResponseBody . toJSONText
+
 -- | Wrapper type for lambda execution results
 data LambdaError =
-  StandaloneLambdaError String |
+  StandaloneLambdaError LambdaResponseBody |
   ApiGatewayLambdaError (ApiGatewayResponse ApiGatewayResponseBody)
 
 -- | Wrapper type to handle the result of the user
 data LambdaResult =
-  StandaloneLambdaResult String |
+  StandaloneLambdaResult LambdaResponseBody |
   ApiGatewayResult (ApiGatewayResponse ApiGatewayResponseBody)
 
 -- | Options that the generated main expects

src/Aws/Lambda/Runtime/Publish.hs

@@ -9,7 +9,7 @@ module Aws.Lambda.Runtime.Publish
 
 import Control.Monad (void)
 import Data.Aeson
-import qualified Data.ByteString.Char8 as ByteString
+import qualified Data.Text.Encoding as T
 import qualified Network.HTTP.Client as Http
 
 import qualified Aws.Lambda.Runtime.API.Endpoints as Endpoints
@@ -24,7 +24,7 @@ result lambdaResult lambdaApi context manager = do
   rawRequest <- Http.parseRequest endpoint
 
   let requestBody = case lambdaResult of
-        (StandaloneLambdaResult res) -> Http.RequestBodyBS (ByteString.pack res)
+        (StandaloneLambdaResult res) -> Http.RequestBodyBS (T.encodeUtf8 . unLambdaResponseBody $ res)
         (ApiGatewayResult res)       -> Http.RequestBodyLBS (encode res)
       request = rawRequest
                 { Http.method = "POST"

src/Aws/Lambda/Utilities.hs

@@ -0,0 +1,9 @@
+module Aws.Lambda.Utilities (toJSONText) where
+
+import Data.Aeson
+import qualified Data.ByteString.Lazy.Char8 as LazyByteString
+import Data.Text
+import qualified Data.Text as T
+
+toJSONText :: ToJSON a => a -> Text
+toJSONText = T.pack . LazyByteString.unpack . encode