d0414be · typeable/aeson

git.iko.soy/typeable/aeson

Fix .:? behavior for #83

It makes (.:?) return Just value if the key is present for values of type Maybe a. Earlier {"key": null} .:? "key" would return Nothing although the key is there. It was not possible to distinguish the cases when key is absent and when value is null. Now it treats Maybe same way as other types and returns Just Nothing.

commitd0414be92ee6bf5b4c057978955b89d111767dab authorBoris Lykah <blykah@stilo.com> dateThu 18 Dec 2014, 13:42 (12 years ago) parent599dc77

3 files changed+7−6

compare with master

unifiedsplit

Data/Aeson/TH.hs+3−2 Data/Aeson/Types/Generic.hs+3−3 Data/Aeson/Types/Instances.hs+1−1

Data/Aeson/TH.hs+3−2

@@ -100,7 +100,8 @@ import Data.Aeson.Types ( Value(..), Parser

100100 , defaultTaggedObject

101101 )

102102import Data.Aeson.Types.Internal (Encoding(..))

103−import Data.Bool ( Bool(False, True), otherwise, (&&) , not)

103+import Control.Monad ( return, mapM, liftM2, fail, join )

104+import Data.Bool ( Bool(False, True), otherwise, (&&), not )

104105import Data.Either ( Either(Left, Right) )

105106import Data.Eq ( (==) )

106107import Data.Function ( ($), (.), flip )

@@ -953,7 +954,7 @@ instance (FromJSON a) => LookupField a where

953954 Just v -> parseJSON v

954955

955956instance (FromJSON a) => LookupField (Maybe a) where

956− lookupField _ _ = (.:?)

957+ lookupField _ _ obj key = join <$> obj .:? key

957958

958959unknownFieldFail :: String -> String -> String -> Parser fail

959960unknownFieldFail tName rec key =

Data/Aeson/Types/Generic.hs+3−3

@@ -20,7 +20,7 @@

2020module Data.Aeson.Types.Generic ( ) where

2121

2222import Control.Applicative ((<*>), (<$>), (<|>), pure)

23−import Control.Monad ((<=<))

23+import Control.Monad ((<=<), join)

2424import Control.Monad.ST (ST)

2525import Data.Aeson.Encode.Builder (emptyArray_)

2626import Data.Aeson.Encode.Functions (builder)

@@ -656,8 +656,8 @@ instance (Selector s, GFromJSON a) => FromRecord (S1 s a) where

656656 {-# INLINE parseRecord #-}

657657

658658instance (Selector s, FromJSON a) => FromRecord (S1 s (K1 i (Maybe a))) where

659− parseRecord _ (Just lab) obj = (M1 . K1) <$> obj .:? lab

660− parseRecord opts Nothing obj = (M1 . K1) <$> obj .:? pack label

659+ parseRecord _ (Just lab) obj = (M1 . K1) . join <$> obj .:? lab

660+ parseRecord opts Nothing obj = (M1 . K1) . join <$> obj .:? pack label

661661 where

662662 label = fieldLabelModifier opts $

663663 selName (undefined :: t s (K1 i (Maybe a)) p)

Data/Aeson/Types/Instances.hs+1−1

@@ -1525,7 +1525,7 @@ obj .: key = case H.lookup key obj of

15251525(.:?) :: (FromJSON a) => Object -> Text -> Parser (Maybe a)

15261526obj .:? key = case H.lookup key obj of

15271527 Nothing -> pure Nothing

1528− Just v -> parseJSON v <?> Key key

1528+ Just v -> Just <$> parseJSON v <?> Key key

15291529{-# INLINE (.:?) #-}

15301530

15311531-- | Helper for use in combination with '.:?' to provide default