eb11f43 · typeable/aeson

git.iko.soy/typeable/aeson

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Merge pull request #50 from hvr/defaulting-operator

eb11f43Bryan O'Sullivan15 years ago

Data/Aeson.hs+1

compare with master

unifiedsplit

@@ -31,6 +31,7 @@ module Data.Aeson

31 , (.=)

32 , (.:)

33 , (.:?)

34+ , (.!=)

34 , (.:/)

35 , (.:/)

35 , object

36 , object

36 -- * Parsing

37 -- * Parsing

Data/Aeson/Types.hs+1

@@ -35,6 +35,7 @@ module Data.Aeson.Types

35 , (.=)

36 , (.:)

37 , (.:?)

38+ , (.!=)

38 , (.:/)

39 , (.:/)

39 , object

40 , object

40 ) where

41 ) where

Data/Aeson/Types/Class.hs+21

@@ -33,6 +33,7 @@ module Data.Aeson.Types.Class

33 , fromJSON

34 , (.:)

35 , (.:?)

36+ , (.!=)

36 , (.:/)

37 , (.:/)

37 , (.=)

38 , (.=)

38 , typeMismatch

39 , typeMismatch

@@ -44,6 +45,7 @@ import Data.Aeson.Types.Internal

44import Data.Attoparsec.Char8 (Number(..))

45import Data.Attoparsec.Char8 (Number(..))

45import Data.Hashable (Hashable(..))

46import Data.Hashable (Hashable(..))

46import Data.Int (Int8, Int16, Int32, Int64)

47import Data.Int (Int8, Int16, Int32, Int64)

48+import Data.Maybe (fromMaybe)

47import Data.Monoid (Dual(..), First(..), Last(..))

49import Data.Monoid (Dual(..), First(..), Last(..))

48import Data.Ratio (Ratio)

50import Data.Ratio (Ratio)

49import Data.Text (Text, pack, unpack)

51import Data.Text (Text, pack, unpack)

@@ -745,6 +747,22 @@ obj .:? key = case H.lookup key obj of

745 Just v -> parseJSON v

747 Just v -> parseJSON v

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

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

747

749

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

751+-- values for optional JSON object fields.

752+--

753+-- Example usage:

754+--

755+-- @ v1 <- o '.:?' \"opt_field_with_dfl\" .!= \"default_val\"

756+-- v2 <- o '.:' \"mandatory_field\"

757+-- v3 <- o '.:?' \"opt_field2\"

758+--

759+-- \-- alternative version of v1 using the '.:/' operator

760+-- v1' <- o '.:/' (\"opt_field_with_dfl\", \"default_val\")

761+-- @

762+(.!=) :: Parser (Maybe a) -> a -> Parser a

763+pmval .!= val = fromMaybe val <$> pmval

764+{-# INLINE (.!=) #-}

765+

748-- | Retrieve the value associated with the given key of an 'Object'.

766-- | Retrieve the value associated with the given key of an 'Object'.

749-- The result is a default value if the key is not present, or 'empty'

767-- The result is a default value if the key is not present, or 'empty'

750-- if the value cannot be converted to the desired type.

768-- if the value cannot be converted to the desired type.

@@ -753,6 +771,9 @@ obj .:? key = case H.lookup key obj of

753-- from an object without affecting its validity and we know a

771-- from an object without affecting its validity and we know a

754-- default value to assign in that case. If the key and value

772-- default value to assign in that case. If the key and value

755-- are mandatory, use '(.:)' instead.

773-- are mandatory, use '(.:)' instead.

774+--

775+-- See also '.!=' for an alternative way to represent optional fields

776+-- with defaulting.

756(.:/) :: (FromJSON a) => Object -> (Text, a) -> Parser a

777(.:/) :: (FromJSON a) => Object -> (Text, a) -> Parser a

757obj .:/ (key, val) = case H.lookup key obj of

778obj .:/ (key, val) = case H.lookup key obj of

758 Nothing -> pure val

779 Nothing -> pure val