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Created additional getFieldOptional #36

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Created additional getFieldOptional #36

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00e42a1
Added getFieldOptional' to Decode.Combinators
Vlix Aug 29, 2017
30eedac
Merge pull request #1 from Vlix/Vlix-Decode-Combinator
Vlix Aug 29, 2017
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17 changes: 16 additions & 1 deletion src/Data/Argonaut/Decode/Combinators.purs
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Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,7 @@ getField o s =

infix 7 getField as .?

-- | Will return Nothing if the field isn't present
getFieldOptional :: forall a. DecodeJson a => JObject -> String -> Either String (Maybe a)
getFieldOptional o s =
maybe
Expand All @@ -26,7 +27,21 @@ getFieldOptional o s =
where
decode json = Just <$> decodeJson json

infix 7 getFieldOptional as .??
infix 7 getFieldOptional as .?!

-- | Will return Nothing if the field isn't present or the value is null
getFieldOptional' :: forall a. DecodeJson a => JObject -> String -> Either String (Maybe a)
getFieldOptional' o s =
maybe
(pure Nothing)
decodeIt
(SM.lookup s o)
where decodeIt j =
if isNull j
then pure Nothing
else Just <$> decodeJson j

infix 7 getFieldOptional' as .??

defaultField :: forall a. Either String (Maybe a) -> a -> Either String a
defaultField parser default = fromMaybe default <$> parser
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