Module

Data.Argonaut.Decode

Package: purescript-argonaut-codecs
Repository: purescript-contrib/purescript-argonaut-codecs

Re-exports from Data.Argonaut.Decode.Class

#DecodeJson Source

class DecodeJson a  where

Members

decodeJson :: Json -> Either JsonDecodeError a

Instances

(DecodeJson a) => DecodeJson (Identity a)
(DecodeJson a) => DecodeJson (Maybe a)
(DecodeJson a, DecodeJson b) => DecodeJson (Tuple a b)
(DecodeJson a, DecodeJson b) => DecodeJson (Either a b)
DecodeJson Unit
DecodeJson Boolean
DecodeJson Number
DecodeJson Int
DecodeJson String
DecodeJson NonEmptyString
DecodeJson Json
(DecodeJson a) => DecodeJson (NonEmpty Array a)
(DecodeJson a) => DecodeJson (NonEmptyArray a)
(DecodeJson a) => DecodeJson (NonEmpty List a)
(DecodeJson a) => DecodeJson (NonEmptyList a)
DecodeJson CodePoint
(DecodeJson a) => DecodeJson (Object a)
(DecodeJson a) => DecodeJson (Array a)
(DecodeJson a) => DecodeJson (List a)
(Ord a, DecodeJson a) => DecodeJson (Set a)
(Ord a, DecodeJson a, DecodeJson b) => DecodeJson (Map a b)
DecodeJson Void
(GDecodeJson row list, RowToList row list) => DecodeJson (Record row)

Re-exports from Data.Argonaut.Decode.Combinators

#getFieldOptional' Source

getFieldOptional' :: forall a. DecodeJson a => Object Json -> String -> Either JsonDecodeError (Maybe a)

Attempt to get the value for a given key on an Object Json.

The result will be Right Nothing if the key and value are not present, or if the key is present and the value is null.

Use this accessor if the key and value are optional in your object. If the key and value are mandatory, use getField (.:) instead.

#getFieldOptional Source

getFieldOptional :: forall a. DecodeJson a => Object Json -> String -> Either JsonDecodeError (Maybe a)

Attempt to get the value for a given key on an Object Json.

The result will be Right Nothing if the key and value are not present, but will fail if the key is present but the value cannot be converted to the right type.

This function will treat null as a value and attempt to decode it into your desired type. If you would like to treat null values the same as absent values, use getFieldOptional' (.:?) instead.

#getField Source

getField :: forall a. DecodeJson a => Object Json -> String -> Either JsonDecodeError a

Attempt to get the value for a given key on an Object Json.

Use this accessor if the key and value must be present in your object. If the key and value are optional, use getFieldOptional' (.:?) instead.

#defaultField Source

defaultField :: forall a. Either JsonDecodeError (Maybe a) -> a -> Either JsonDecodeError a

Helper for use in combination with .:? to provide default values for optional Object Json fields.

Example usage:

newtype MyType = MyType
  { foo :: String
  , bar :: Maybe Int
  , baz :: Boolean
  }

instance decodeJsonMyType :: DecodeJson MyType where
  decodeJson json = do
    x <- decodeJson json
    foo <- x .: "foo" -- mandatory field
    bar <- x .:? "bar" -- optional field
    baz <- x .:? "baz" .!= false -- optional field with default value of `false`
    pure $ MyType { foo, bar, baz }

#(.:?) Source

Operator alias for Data.Argonaut.Decode.Combinators.getFieldOptional' (non-associative / precedence 7)

#(.:!) Source

Operator alias for Data.Argonaut.Decode.Combinators.getFieldOptional (non-associative / precedence 7)

#(.:) Source

Operator alias for Data.Argonaut.Decode.Combinators.getField (non-associative / precedence 7)

#(.!=) Source

Operator alias for Data.Argonaut.Decode.Combinators.defaultField (non-associative / precedence 6)

Re-exports from Data.Argonaut.Decode.Error

#JsonDecodeError Source

data JsonDecodeError

Error type for failures while decoding.

Constructors

Instances

#printJsonDecodeError Source

printJsonDecodeError :: JsonDecodeError -> String

Prints a JsonDecodeError as a readable error message.

Re-exports from Data.Argonaut.Decode.Parser

#parseJson Source

parseJson :: String -> Either JsonDecodeError Json

Attempt to parse a string as Json, failing with a typed error if the JSON string is malformed.

Modules: Data.Argonaut.Decode; Data.Argonaut.Decode.Class; Data.Argonaut.Decode.Combinators; Data.Argonaut.Decode.Decoders; Data.Argonaut.Decode.Error; Data.Argonaut.Decode.Parser; Data.Argonaut.Encode; Data.Argonaut.Encode.Class; Data.Argonaut.Encode.Combinators; Data.Argonaut.Encode.Encoders