| Safe Haskell | None |
|---|---|
| Language | Haskell2010 |
Pantry.Internal.AesonExtended
Description
Extensions to Aeson parsing of objects. This module is intended for internal use by Pantry and Stack only. The intention is to fully remove this module in the future. DO NOT RELY ON IT.
Synopsis
- eitherDecodeFileStrict' :: FromJSON a => FilePath -> IO (Either String a)
- eitherDecodeStrict' :: FromJSON a => ByteString -> Either String a
- eitherDecode' :: FromJSON a => ByteString -> Either String a
- eitherDecodeFileStrict :: FromJSON a => FilePath -> IO (Either String a)
- eitherDecodeStrict :: FromJSON a => ByteString -> Either String a
- eitherDecode :: FromJSON a => ByteString -> Either String a
- decodeFileStrict' :: FromJSON a => FilePath -> IO (Maybe a)
- decodeStrict' :: FromJSON a => ByteString -> Maybe a
- decode' :: FromJSON a => ByteString -> Maybe a
- decodeFileStrict :: FromJSON a => FilePath -> IO (Maybe a)
- decodeStrict :: FromJSON a => ByteString -> Maybe a
- decode :: FromJSON a => ByteString -> Maybe a
- encodeFile :: ToJSON a => FilePath -> a -> IO ()
- encode :: ToJSON a => a -> ByteString
- foldable :: (Foldable t, ToJSON a) => t a -> Encoding
- type GToJSON = GToJSON Value
- type GToEncoding = GToJSON Encoding
- toEncoding2 :: (ToJSON2 f, ToJSON a, ToJSON b) => f a b -> Encoding
- toJSON2 :: (ToJSON2 f, ToJSON a, ToJSON b) => f a b -> Value
- toEncoding1 :: (ToJSON1 f, ToJSON a) => f a -> Encoding
- toJSON1 :: (ToJSON1 f, ToJSON a) => f a -> Value
- genericToJSONKey :: (Generic a, GToJSONKey (Rep a)) => JSONKeyOptions -> ToJSONKeyFunction a
- genericLiftToEncoding :: (Generic1 f, GToJSON Encoding One (Rep1 f)) => Options -> (a -> Encoding) -> ([a] -> Encoding) -> f a -> Encoding
- genericToEncoding :: (Generic a, GToJSON Encoding Zero (Rep a)) => Options -> a -> Encoding
- genericLiftToJSON :: (Generic1 f, GToJSON Value One (Rep1 f)) => Options -> (a -> Value) -> ([a] -> Value) -> f a -> Value
- genericToJSON :: (Generic a, GToJSON Value Zero (Rep a)) => Options -> a -> Value
- data ToArgs res arity a where
- class ToJSON a where
- toJSON :: a -> Value
- toEncoding :: a -> Encoding
- toJSONList :: [a] -> Value
- toEncodingList :: [a] -> Encoding
- class KeyValue kv where
- class ToJSONKey a where
- toJSONKey :: ToJSONKeyFunction a
- toJSONKeyList :: ToJSONKeyFunction [a]
- data ToJSONKeyFunction a
- = ToJSONKeyText !(a -> Text) !(a -> Encoding' Text)
- | ToJSONKeyValue !(a -> Value) !(a -> Encoding)
- class GetConName f => GToJSONKey (f :: k -> Type)
- class ToJSON1 (f :: Type -> Type) where
- liftToJSON :: (a -> Value) -> ([a] -> Value) -> f a -> Value
- liftToJSONList :: (a -> Value) -> ([a] -> Value) -> [f a] -> Value
- liftToEncoding :: (a -> Encoding) -> ([a] -> Encoding) -> f a -> Encoding
- liftToEncodingList :: (a -> Encoding) -> ([a] -> Encoding) -> [f a] -> Encoding
- class ToJSON2 (f :: Type -> Type -> Type) where
- liftToJSON2 :: (a -> Value) -> ([a] -> Value) -> (b -> Value) -> ([b] -> Value) -> f a b -> Value
- liftToJSONList2 :: (a -> Value) -> ([a] -> Value) -> (b -> Value) -> ([b] -> Value) -> [f a b] -> Value
- liftToEncoding2 :: (a -> Encoding) -> ([a] -> Encoding) -> (b -> Encoding) -> ([b] -> Encoding) -> f a b -> Encoding
- liftToEncodingList2 :: (a -> Encoding) -> ([a] -> Encoding) -> (b -> Encoding) -> ([b] -> Encoding) -> [f a b] -> Encoding
- pairs :: Series -> Encoding
- fromEncoding :: Encoding' tag -> Builder
- type Encoding = Encoding' Value
- data Series
- (.!=) :: Parser (Maybe a) -> a -> Parser a
- (.:!) :: FromJSON a => Object -> Text -> Parser (Maybe a)
- fromJSON :: FromJSON a => Value -> Result a
- withEmbeddedJSON :: String -> (Value -> Parser a) -> Value -> Parser a
- withBool :: String -> (Bool -> Parser a) -> Value -> Parser a
- withScientific :: String -> (Scientific -> Parser a) -> Value -> Parser a
- withArray :: String -> (Array -> Parser a) -> Value -> Parser a
- withText :: String -> (Text -> Parser a) -> Value -> Parser a
- withObject :: String -> (Object -> Parser a) -> Value -> Parser a
- parseJSON2 :: (FromJSON2 f, FromJSON a, FromJSON b) => Value -> Parser (f a b)
- parseJSON1 :: (FromJSON1 f, FromJSON a) => Value -> Parser (f a)
- genericFromJSONKey :: (Generic a, GFromJSONKey (Rep a)) => JSONKeyOptions -> FromJSONKeyFunction a
- genericLiftParseJSON :: (Generic1 f, GFromJSON One (Rep1 f)) => Options -> (Value -> Parser a) -> (Value -> Parser [a]) -> Value -> Parser (f a)
- genericParseJSON :: (Generic a, GFromJSON Zero (Rep a)) => Options -> Value -> Parser a
- parseIndexedJSON :: (Value -> Parser a) -> Int -> Value -> Parser a
- class GFromJSON arity (f :: Type -> Type) where
- gParseJSON :: Options -> FromArgs arity a -> Value -> Parser (f a)
- data FromArgs arity a where
- class FromJSON a where
- class FromJSONKey a where
- data FromJSONKeyFunction a
- = FromJSONKeyCoerce !(CoerceText a)
- | FromJSONKeyText !(Text -> a)
- | FromJSONKeyTextParser !(Text -> Parser a)
- | FromJSONKeyValue !(Value -> Parser a)
- class (ConstructorNames f, SumFromString f) => GFromJSONKey (f :: Type -> Type)
- class FromJSON1 (f :: Type -> Type) where
- class FromJSON2 (f :: Type -> Type -> Type) where
- json' :: Parser Value
- json :: Parser Value
- camelTo2 :: Char -> String -> String
- defaultJSONKeyOptions :: JSONKeyOptions
- defaultTaggedObject :: SumEncoding
- defaultOptions :: Options
- (<?>) :: Parser a -> JSONPathElement -> Parser a
- object :: [Pair] -> Value
- type JSONPath = [JSONPathElement]
- data Result a
- type Object = HashMap Text Value
- type Array = Vector Value
- data Value
- newtype DotNetTime = DotNetTime {}
- data Options
- data SumEncoding
- data JSONKeyOptions
- data Zero
- data One
- (.:) :: FromJSON a => Object -> Text -> Parser a
- (.:?) :: FromJSON a => Object -> Text -> Parser (Maybe a)
- data JSONWarning
- type WarningParser a = WriterT WarningParserMonoid Parser a
- data WithJSONWarnings a = WithJSONWarnings a [JSONWarning]
- withObjectWarnings :: String -> (Object -> WarningParser a) -> Value -> Parser (WithJSONWarnings a)
- jsonSubWarnings :: WarningParser (WithJSONWarnings a) -> WarningParser a
- jsonSubWarningsT :: Traversable t => WarningParser (t (WithJSONWarnings a)) -> WarningParser (t a)
- jsonSubWarningsTT :: (Traversable t, Traversable u) => WarningParser (u (t (WithJSONWarnings a))) -> WarningParser (u (t a))
- logJSONWarnings :: (MonadReader env m, HasLogFunc env, HasCallStack, MonadIO m) => FilePath -> [JSONWarning] -> m ()
- noJSONWarnings :: a -> WithJSONWarnings a
- tellJSONField :: Text -> WarningParser ()
- unWarningParser :: WarningParser a -> Parser a
- (..:) :: FromJSON a => Object -> Text -> WarningParser a
- (...:) :: FromJSON a => Object -> [Text] -> WarningParser a
- (..:?) :: FromJSON a => Object -> Text -> WarningParser (Maybe a)
- (...:?) :: FromJSON a => Object -> [Text] -> WarningParser (Maybe a)
- (..!=) :: WarningParser (Maybe a) -> a -> WarningParser a
Documentation
eitherDecodeFileStrict' :: FromJSON a => FilePath -> IO (Either String a) Source #
Like decodeFileStrict' but returns an error message when decoding fails.
eitherDecodeStrict' :: FromJSON a => ByteString -> Either String a Source #
Like decodeStrict' but returns an error message when decoding fails.
eitherDecode' :: FromJSON a => ByteString -> Either String a Source #
Like decode' but returns an error message when decoding fails.
eitherDecodeFileStrict :: FromJSON a => FilePath -> IO (Either String a) Source #
Like decodeFileStrict but returns an error message when decoding fails.
eitherDecodeStrict :: FromJSON a => ByteString -> Either String a Source #
Like decodeStrict but returns an error message when decoding fails.
eitherDecode :: FromJSON a => ByteString -> Either String a Source #
Like decode but returns an error message when decoding fails.
decodeFileStrict' :: FromJSON a => FilePath -> IO (Maybe a) Source #
Efficiently deserialize a JSON value from a file.
If this fails due to incomplete or invalid input, Nothing is
returned.
The input file's content must consist solely of a JSON document, with no trailing data except for whitespace.
This function parses and performs conversion immediately. See
json' for details.
decodeStrict' :: FromJSON a => ByteString -> Maybe a Source #
Efficiently deserialize a JSON value from a strict ByteString.
If this fails due to incomplete or invalid input, Nothing is
returned.
The input must consist solely of a JSON document, with no trailing data except for whitespace.
This function parses and performs conversion immediately. See
json' for details.
decode' :: FromJSON a => ByteString -> Maybe a Source #
Efficiently deserialize a JSON value from a lazy ByteString.
If this fails due to incomplete or invalid input, Nothing is
returned.
The input must consist solely of a JSON document, with no trailing data except for whitespace.
This function parses and performs conversion immediately. See
json' for details.
decodeFileStrict :: FromJSON a => FilePath -> IO (Maybe a) Source #
Efficiently deserialize a JSON value from a file.
If this fails due to incomplete or invalid input, Nothing is
returned.
The input file's content must consist solely of a JSON document, with no trailing data except for whitespace.
This function parses immediately, but defers conversion. See
json for details.
decodeStrict :: FromJSON a => ByteString -> Maybe a Source #
Efficiently deserialize a JSON value from a strict ByteString.
If this fails due to incomplete or invalid input, Nothing is
returned.
The input must consist solely of a JSON document, with no trailing data except for whitespace.
This function parses immediately, but defers conversion. See
json for details.
decode :: FromJSON a => ByteString -> Maybe a Source #
Efficiently deserialize a JSON value from a lazy ByteString.
If this fails due to incomplete or invalid input, Nothing is
returned.
The input must consist solely of a JSON document, with no trailing data except for whitespace.
This function parses immediately, but defers conversion. See
json for details.
encodeFile :: ToJSON a => FilePath -> a -> IO () Source #
Efficiently serialize a JSON value as a lazy ByteString and write it to a file.
encode :: ToJSON a => a -> ByteString Source #
Efficiently serialize a JSON value as a lazy ByteString.
This is implemented in terms of the ToJSON class's toEncoding method.
type GToEncoding = GToJSON Encoding Source #
toEncoding2 :: (ToJSON2 f, ToJSON a, ToJSON b) => f a b -> Encoding Source #
Lift the standard toEncoding function through the type constructor.
toJSON2 :: (ToJSON2 f, ToJSON a, ToJSON b) => f a b -> Value Source #
Lift the standard toJSON function through the type constructor.
toEncoding1 :: (ToJSON1 f, ToJSON a) => f a -> Encoding Source #
Lift the standard toEncoding function through the type constructor.
toJSON1 :: (ToJSON1 f, ToJSON a) => f a -> Value Source #
Lift the standard toJSON function through the type constructor.
genericToJSONKey :: (Generic a, GToJSONKey (Rep a)) => JSONKeyOptions -> ToJSONKeyFunction a Source #
genericLiftToEncoding :: (Generic1 f, GToJSON Encoding One (Rep1 f)) => Options -> (a -> Encoding) -> ([a] -> Encoding) -> f a -> Encoding Source #
A configurable generic JSON encoder. This function applied to
defaultOptions is used as the default for liftToEncoding when the type
is an instance of Generic1.
genericToEncoding :: (Generic a, GToJSON Encoding Zero (Rep a)) => Options -> a -> Encoding Source #
A configurable generic JSON encoder. This function applied to
defaultOptions is used as the default for toEncoding when the type
is an instance of Generic.
genericLiftToJSON :: (Generic1 f, GToJSON Value One (Rep1 f)) => Options -> (a -> Value) -> ([a] -> Value) -> f a -> Value Source #
A configurable generic JSON creator. This function applied to
defaultOptions is used as the default for liftToJSON when the type
is an instance of Generic1.
genericToJSON :: (Generic a, GToJSON Value Zero (Rep a)) => Options -> a -> Value Source #
A configurable generic JSON creator. This function applied to
defaultOptions is used as the default for toJSON when the type
is an instance of Generic.
A type that can be converted to JSON.
Instances in general must specify toJSON and should (but don't need
to) specify toEncoding.
An example type and instance:
-- Allow ourselves to writeTextliterals. {-# LANGUAGE OverloadedStrings #-} data Coord = Coord { x :: Double, y :: Double } instanceToJSONCoord wheretoJSON(Coord x y) =object["x".=x, "y".=y]toEncoding(Coord x y) =pairs("x".=x<>"y".=y)
Instead of manually writing your ToJSON instance, there are two options
to do it automatically:
- Data.Aeson.TH provides Template Haskell functions which will derive an instance at compile time. The generated instance is optimized for your type so it will probably be more efficient than the following option.
- The compiler can provide a default generic implementation for
toJSON.
To use the second, simply add a deriving clause to your
datatype and declare a GenericToJSON instance. If you require nothing other than
defaultOptions, it is sufficient to write (and this is the only
alternative where the default toJSON implementation is sufficient):
{-# LANGUAGE DeriveGeneric #-}
import GHC.Generics
data Coord = Coord { x :: Double, y :: Double } deriving Generic
instance ToJSON Coord where
toEncoding = genericToEncoding defaultOptions
If on the other hand you wish to customize the generic decoding, you have to implement both methods:
customOptions =defaultOptions{fieldLabelModifier=maptoUpper} instanceToJSONCoord wheretoJSON=genericToJSONcustomOptionstoEncoding=genericToEncodingcustomOptions
Previous versions of this library only had the toJSON method. Adding
toEncoding had two reasons:
- toEncoding is more efficient for the common case that the output of
toJSONis directly serialized to aByteString. Further, expressing either method in terms of the other would be non-optimal. - The choice of defaults allows a smooth transition for existing users:
Existing instances that do not define
toEncodingstill compile and have the correct semantics. This is ensured by making the default implementation oftoEncodingusetoJSON. This produces correct results, but since it performs an intermediate conversion to aValue, it will be less efficient than directly emitting anEncoding. (this also means that specifying nothing more thaninstance ToJSON Coordwould be sufficient as a generically decoding instance, but there probably exists no good reason to not specifytoEncodingin new instances.)
Minimal complete definition
Nothing
Methods
Convert a Haskell value to a JSON-friendly intermediate type.
toEncoding :: a -> Encoding Source #
Encode a Haskell value as JSON.
The default implementation of this method creates an
intermediate Value using toJSON. This provides
source-level compatibility for people upgrading from older
versions of this library, but obviously offers no performance
advantage.
To benefit from direct encoding, you must provide an
implementation for this method. The easiest way to do so is by
having your types implement Generic using the DeriveGeneric
extension, and then have GHC generate a method body as follows.
instanceToJSONCoord wheretoEncoding=genericToEncodingdefaultOptions
toJSONList :: [a] -> Value Source #
toEncodingList :: [a] -> Encoding Source #
Instances
class KeyValue kv where Source #
A key-value pair for encoding a JSON object.
class ToJSONKey a where Source #
Typeclass for types that can be used as the key of a map-like container
(like Map or HashMap). For example, since Text has a ToJSONKey
instance and Char has a ToJSON instance, we can encode a value of
type Map Text Char:
>>>LBC8.putStrLn $ encode $ Map.fromList [("foo" :: Text, 'a')]{"foo":"a"}
Since Int also has a ToJSONKey instance, we can similarly write:
>>>LBC8.putStrLn $ encode $ Map.fromList [(5 :: Int, 'a')]{"5":"a"}
JSON documents only accept strings as object keys. For any type
from base that has a natural textual representation, it can be
expected that its ToJSONKey instance will choose that representation.
For data types that lack a natural textual representation, an alternative is provided. The map-like container is represented as a JSON array instead of a JSON object. Each value in the array is an array with exactly two values. The first is the key and the second is the value.
For example, values of type '[Text]' cannot be encoded to a
string, so a Map with keys of type '[Text]' is encoded as follows:
>>>LBC8.putStrLn $ encode $ Map.fromList [(["foo","bar","baz" :: Text], 'a')][[["foo","bar","baz"],"a"]]
The default implementation of ToJSONKey chooses this method of
encoding a key, using the ToJSON instance of the type.
To use your own data type as the key in a map, all that is needed
is to write a ToJSONKey (and possibly a FromJSONKey) instance
for it. If the type cannot be trivially converted to and from Text,
it is recommended that ToJSONKeyValue is used. Since the default
implementations of the typeclass methods can build this from a
ToJSON instance, there is nothing that needs to be written:
data Foo = Foo { fooAge :: Int, fooName :: Text }
deriving (Eq,Ord,Generic)
instance ToJSON Foo
instance ToJSONKey FooThat's it. We can now write:
>>>let m = Map.fromList [(Foo 4 "bar",'a'),(Foo 6 "arg",'b')]>>>LBC8.putStrLn $ encode m[[{"fooName":"bar","fooAge":4},"a"],[{"fooName":"arg","fooAge":6},"b"]]
The next case to consider is if we have a type that is a
newtype wrapper around Text. The recommended approach is to use
generalized newtype deriving:
newtype RecordId = RecordId { getRecordId :: Text }
deriving (Eq,Ord,ToJSONKey)Then we may write:
>>>LBC8.putStrLn $ encode $ Map.fromList [(RecordId "abc",'a')]{"abc":"a"}
Simple sum types are a final case worth considering. Suppose we have:
data Color = Red | Green | Blue deriving (Show,Read,Eq,Ord)
It is possible to get the ToJSONKey instance for free as we did
with Foo. However, in this case, we have a natural way to go to
and from Text that does not require any escape sequences. So
ToJSONKeyText can be used instead of ToJSONKeyValue to encode maps
as objects instead of arrays of pairs. This instance may be
implemented using generics as follows:
instanceToJSONKeyColor wheretoJSONKey=genericToJSONKeydefaultJSONKeyOptions
Low-level implementations
The Show instance can be used to help write ToJSONKey:
instance ToJSONKey Color where
toJSONKey = ToJSONKeyText f g
where f = Text.pack . show
g = text . Text.pack . show
-- text function is from Data.Aeson.EncodingThe situation of needing to turning function a -> Text into
a ToJSONKeyFunction is common enough that a special combinator
is provided for it. The above instance can be rewritten as:
instance ToJSONKey Color where toJSONKey = toJSONKeyText (Text.pack . show)
The performance of the above instance can be improved by
not using String as an intermediate step when converting to
Text. One option for improving performance would be to use
template haskell machinery from the text-show package. However,
even with the approach, the Encoding (a wrapper around a bytestring
builder) is generated by encoding the Text to a ByteString,
an intermediate step that could be avoided. The fastest possible
implementation would be:
-- Assuming that OverloadedStrings is enabled
instance ToJSONKey Color where
toJSONKey = ToJSONKeyText f g
where f x = case x of {Red -> "Red";Green ->"Green";Blue -> "Blue"}
g x = case x of {Red -> text "Red";Green -> text "Green";Blue -> text "Blue"}
-- text function is from Data.Aeson.EncodingThis works because GHC can lift the encoded values out of the case statements, which means that they are only evaluated once. This approach should only be used when there is a serious need to maximize performance.
Minimal complete definition
Nothing
Methods
toJSONKey :: ToJSONKeyFunction a Source #
Strategy for rendering the key for a map-like container.
toJSONKeyList :: ToJSONKeyFunction [a] Source #
Instances
data ToJSONKeyFunction a Source #
Constructors
| ToJSONKeyText !(a -> Text) !(a -> Encoding' Text) | key is encoded to string, produces object |
| ToJSONKeyValue !(a -> Value) !(a -> Encoding) | key is encoded to value, produces array |
Instances
| Contravariant ToJSONKeyFunction | |
Defined in Data.Aeson.Types.ToJSON Methods contramap :: (a -> b) -> ToJSONKeyFunction b -> ToJSONKeyFunction a Source # (>$) :: b -> ToJSONKeyFunction b -> ToJSONKeyFunction a Source # | |
class GetConName f => GToJSONKey (f :: k -> Type) Source #
Instances
| GetConName f => GToJSONKey (f :: k -> Type) | |
Defined in Data.Aeson.Types.ToJSON | |
class ToJSON1 (f :: Type -> Type) where Source #
Lifting of the ToJSON class to unary type constructors.
Instead of manually writing your ToJSON1 instance, there are two options
to do it automatically:
- Data.Aeson.TH provides Template Haskell functions which will derive an instance at compile time. The generated instance is optimized for your type so it will probably be more efficient than the following option.
- The compiler can provide a default generic implementation for
toJSON1.
To use the second, simply add a deriving clause to your
datatype and declare a Generic1ToJSON1 instance for your datatype without giving
definitions for liftToJSON or liftToEncoding.
For example:
{-# LANGUAGE DeriveGeneric #-}
import GHC.Generics
data Pair = Pair { pairFst :: a, pairSnd :: b } deriving Generic1
instance ToJSON a => ToJSON1 (Pair a)
If the default implementation doesn't give exactly the results you want,
you can customize the generic encoding with only a tiny amount of
effort, using genericLiftToJSON and genericLiftToEncoding with
your preferred Options:
customOptions =defaultOptions{fieldLabelModifier=maptoUpper} instanceToJSONa =>ToJSON1(Pair a) whereliftToJSON=genericLiftToJSONcustomOptionsliftToEncoding=genericLiftToEncodingcustomOptions
See also ToJSON.
Minimal complete definition
Nothing
Methods
liftToJSON :: (a -> Value) -> ([a] -> Value) -> f a -> Value Source #
liftToJSONList :: (a -> Value) -> ([a] -> Value) -> [f a] -> Value Source #
liftToEncoding :: (a -> Encoding) -> ([a] -> Encoding) -> f a -> Encoding Source #
liftToEncodingList :: (a -> Encoding) -> ([a] -> Encoding) -> [f a] -> Encoding Source #
Instances
class ToJSON2 (f :: Type -> Type -> Type) where Source #
Lifting of the ToJSON class to binary type constructors.
Instead of manually writing your ToJSON2 instance, Data.Aeson.TH
provides Template Haskell functions which will derive an instance at compile time.
The compiler cannot provide a default generic implementation for liftToJSON2,
unlike toJSON and liftToJSON.
Minimal complete definition
Methods
liftToJSON2 :: (a -> Value) -> ([a] -> Value) -> (b -> Value) -> ([b] -> Value) -> f a b -> Value Source #
liftToJSONList2 :: (a -> Value) -> ([a] -> Value) -> (b -> Value) -> ([b] -> Value) -> [f a b] -> Value Source #
liftToEncoding2 :: (a -> Encoding) -> ([a] -> Encoding) -> (b -> Encoding) -> ([b] -> Encoding) -> f a b -> Encoding Source #
liftToEncodingList2 :: (a -> Encoding) -> ([a] -> Encoding) -> (b -> Encoding) -> ([b] -> Encoding) -> [f a b] -> Encoding Source #
Instances
| ToJSON2 Either | |
Defined in Data.Aeson.Types.ToJSON Methods liftToJSON2 :: (a -> Value) -> ([a] -> Value) -> (b -> Value) -> ([b] -> Value) -> Either a b -> Value Source # liftToJSONList2 :: (a -> Value) -> ([a] -> Value) -> (b -> Value) -> ([b] -> Value) -> [Either a b] -> Value Source # liftToEncoding2 :: (a -> Encoding) -> ([a] -> Encoding) -> (b -> Encoding) -> ([b] -> Encoding) -> Either a b -> Encoding Source # liftToEncodingList2 :: (a -> Encoding) -> ([a] -> Encoding) -> (b -> Encoding) -> ([b] -> Encoding) -> [Either a b] -> Encoding Source # | |
| ToJSON2 (,) | |
Defined in Data.Aeson.Types.ToJSON Methods liftToJSON2 :: (a -> Value) -> ([a] -> Value) -> (b -> Value) -> ([b] -> Value) -> (a, b) -> Value Source # liftToJSONList2 :: (a -> Value) -> ([a] -> Value) -> (b -> Value) -> ([b] -> Value) -> [(a, b)] -> Value Source # liftToEncoding2 :: (a -> Encoding) -> ([a] -> Encoding) -> (b -> Encoding) -> ([b] -> Encoding) -> (a, b) -> Encoding Source # liftToEncodingList2 :: (a -> Encoding) -> ([a] -> Encoding) -> (b -> Encoding) -> ([b] -> Encoding) -> [(a, b)] -> Encoding Source # | |
| ToJSON a => ToJSON2 ((,,) a) | |
Defined in Data.Aeson.Types.ToJSON Methods liftToJSON2 :: (a0 -> Value) -> ([a0] -> Value) -> (b -> Value) -> ([b] -> Value) -> (a, a0, b) -> Value Source # liftToJSONList2 :: (a0 -> Value) -> ([a0] -> Value) -> (b -> Value) -> ([b] -> Value) -> [(a, a0, b)] -> Value Source # liftToEncoding2 :: (a0 -> Encoding) -> ([a0] -> Encoding) -> (b -> Encoding) -> ([b] -> Encoding) -> (a, a0, b) -> Encoding Source # liftToEncodingList2 :: (a0 -> Encoding) -> ([a0] -> Encoding) -> (b -> Encoding) -> ([b] -> Encoding) -> [(a, a0, b)] -> Encoding Source # | |
| ToJSON2 (Const :: Type -> Type -> Type) | |
Defined in Data.Aeson.Types.ToJSON Methods liftToJSON2 :: (a -> Value) -> ([a] -> Value) -> (b -> Value) -> ([b] -> Value) -> Const a b -> Value Source # liftToJSONList2 :: (a -> Value) -> ([a] -> Value) -> (b -> Value) -> ([b] -> Value) -> [Const a b] -> Value Source # liftToEncoding2 :: (a -> Encoding) -> ([a] -> Encoding) -> (b -> Encoding) -> ([b] -> Encoding) -> Const a b -> Encoding Source # liftToEncodingList2 :: (a -> Encoding) -> ([a] -> Encoding) -> (b -> Encoding) -> ([b] -> Encoding) -> [Const a b] -> Encoding Source # | |
| ToJSON2 (Tagged :: Type -> Type -> Type) | |
Defined in Data.Aeson.Types.ToJSON Methods liftToJSON2 :: (a -> Value) -> ([a] -> Value) -> (b -> Value) -> ([b] -> Value) -> Tagged a b -> Value Source # liftToJSONList2 :: (a -> Value) -> ([a] -> Value) -> (b -> Value) -> ([b] -> Value) -> [Tagged a b] -> Value Source # liftToEncoding2 :: (a -> Encoding) -> ([a] -> Encoding) -> (b -> Encoding) -> ([b] -> Encoding) -> Tagged a b -> Encoding Source # liftToEncodingList2 :: (a -> Encoding) -> ([a] -> Encoding) -> (b -> Encoding) -> ([b] -> Encoding) -> [Tagged a b] -> Encoding Source # | |
| (ToJSON a, ToJSON b) => ToJSON2 ((,,,) a b) | |
Defined in Data.Aeson.Types.ToJSON Methods liftToJSON2 :: (a0 -> Value) -> ([a0] -> Value) -> (b0 -> Value) -> ([b0] -> Value) -> (a, b, a0, b0) -> Value Source # liftToJSONList2 :: (a0 -> Value) -> ([a0] -> Value) -> (b0 -> Value) -> ([b0] -> Value) -> [(a, b, a0, b0)] -> Value Source # liftToEncoding2 :: (a0 -> Encoding) -> ([a0] -> Encoding) -> (b0 -> Encoding) -> ([b0] -> Encoding) -> (a, b, a0, b0) -> Encoding Source # liftToEncodingList2 :: (a0 -> Encoding) -> ([a0] -> Encoding) -> (b0 -> Encoding) -> ([b0] -> Encoding) -> [(a, b, a0, b0)] -> Encoding Source # | |
| (ToJSON a, ToJSON b, ToJSON c) => ToJSON2 ((,,,,) a b c) | |
Defined in Data.Aeson.Types.ToJSON Methods liftToJSON2 :: (a0 -> Value) -> ([a0] -> Value) -> (b0 -> Value) -> ([b0] -> Value) -> (a, b, c, a0, b0) -> Value Source # liftToJSONList2 :: (a0 -> Value) -> ([a0] -> Value) -> (b0 -> Value) -> ([b0] -> Value) -> [(a, b, c, a0, b0)] -> Value Source # liftToEncoding2 :: (a0 -> Encoding) -> ([a0] -> Encoding) -> (b0 -> Encoding) -> ([b0] -> Encoding) -> (a, b, c, a0, b0) -> Encoding Source # liftToEncodingList2 :: (a0 -> Encoding) -> ([a0] -> Encoding) -> (b0 -> Encoding) -> ([b0] -> Encoding) -> [(a, b, c, a0, b0)] -> Encoding Source # | |
| (ToJSON a, ToJSON b, ToJSON c, ToJSON d) => ToJSON2 ((,,,,,) a b c d) | |
Defined in Data.Aeson.Types.ToJSON Methods liftToJSON2 :: (a0 -> Value) -> ([a0] -> Value) -> (b0 -> Value) -> ([b0] -> Value) -> (a, b, c, d, a0, b0) -> Value Source # liftToJSONList2 :: (a0 -> Value) -> ([a0] -> Value) -> (b0 -> Value) -> ([b0] -> Value) -> [(a, b, c, d, a0, b0)] -> Value Source # liftToEncoding2 :: (a0 -> Encoding) -> ([a0] -> Encoding) -> (b0 -> Encoding) -> ([b0] -> Encoding) -> (a, b, c, d, a0, b0) -> Encoding Source # liftToEncodingList2 :: (a0 -> Encoding) -> ([a0] -> Encoding) -> (b0 -> Encoding) -> ([b0] -> Encoding) -> [(a, b, c, d, a0, b0)] -> Encoding Source # | |
| (ToJSON a, ToJSON b, ToJSON c, ToJSON d, ToJSON e) => ToJSON2 ((,,,,,,) a b c d e) | |
Defined in Data.Aeson.Types.ToJSON Methods liftToJSON2 :: (a0 -> Value) -> ([a0] -> Value) -> (b0 -> Value) -> ([b0] -> Value) -> (a, b, c, d, e, a0, b0) -> Value Source # liftToJSONList2 :: (a0 -> Value) -> ([a0] -> Value) -> (b0 -> Value) -> ([b0] -> Value) -> [(a, b, c, d, e, a0, b0)] -> Value Source # liftToEncoding2 :: (a0 -> Encoding) -> ([a0] -> Encoding) -> (b0 -> Encoding) -> ([b0] -> Encoding) -> (a, b, c, d, e, a0, b0) -> Encoding Source # liftToEncodingList2 :: (a0 -> Encoding) -> ([a0] -> Encoding) -> (b0 -> Encoding) -> ([b0] -> Encoding) -> [(a, b, c, d, e, a0, b0)] -> Encoding Source # | |
| (ToJSON a, ToJSON b, ToJSON c, ToJSON d, ToJSON e, ToJSON f) => ToJSON2 ((,,,,,,,) a b c d e f) | |
Defined in Data.Aeson.Types.ToJSON Methods liftToJSON2 :: (a0 -> Value) -> ([a0] -> Value) -> (b0 -> Value) -> ([b0] -> Value) -> (a, b, c, d, e, f, a0, b0) -> Value Source # liftToJSONList2 :: (a0 -> Value) -> ([a0] -> Value) -> (b0 -> Value) -> ([b0] -> Value) -> [(a, b, c, d, e, f, a0, b0)] -> Value Source # liftToEncoding2 :: (a0 -> Encoding) -> ([a0] -> Encoding) -> (b0 -> Encoding) -> ([b0] -> Encoding) -> (a, b, c, d, e, f, a0, b0) -> Encoding Source # liftToEncodingList2 :: (a0 -> Encoding) -> ([a0] -> Encoding) -> (b0 -> Encoding) -> ([b0] -> Encoding) -> [(a, b, c, d, e, f, a0, b0)] -> Encoding Source # | |
| (ToJSON a, ToJSON b, ToJSON c, ToJSON d, ToJSON e, ToJSON f, ToJSON g) => ToJSON2 ((,,,,,,,,) a b c d e f g) | |
Defined in Data.Aeson.Types.ToJSON Methods liftToJSON2 :: (a0 -> Value) -> ([a0] -> Value) -> (b0 -> Value) -> ([b0] -> Value) -> (a, b, c, d, e, f, g, a0, b0) -> Value Source # liftToJSONList2 :: (a0 -> Value) -> ([a0] -> Value) -> (b0 -> Value) -> ([b0] -> Value) -> [(a, b, c, d, e, f, g, a0, b0)] -> Value Source # liftToEncoding2 :: (a0 -> Encoding) -> ([a0] -> Encoding) -> (b0 -> Encoding) -> ([b0] -> Encoding) -> (a, b, c, d, e, f, g, a0, b0) -> Encoding Source # liftToEncodingList2 :: (a0 -> Encoding) -> ([a0] -> Encoding) -> (b0 -> Encoding) -> ([b0] -> Encoding) -> [(a, b, c, d, e, f, g, a0, b0)] -> Encoding Source # | |
| (ToJSON a, ToJSON b, ToJSON c, ToJSON d, ToJSON e, ToJSON f, ToJSON g, ToJSON h) => ToJSON2 ((,,,,,,,,,) a b c d e f g h) | |
Defined in Data.Aeson.Types.ToJSON Methods liftToJSON2 :: (a0 -> Value) -> ([a0] -> Value) -> (b0 -> Value) -> ([b0] -> Value) -> (a, b, c, d, e, f, g, h, a0, b0) -> Value Source # liftToJSONList2 :: (a0 -> Value) -> ([a0] -> Value) -> (b0 -> Value) -> ([b0] -> Value) -> [(a, b, c, d, e, f, g, h, a0, b0)] -> Value Source # liftToEncoding2 :: (a0 -> Encoding) -> ([a0] -> Encoding) -> (b0 -> Encoding) -> ([b0] -> Encoding) -> (a, b, c, d, e, f, g, h, a0, b0) -> Encoding Source # liftToEncodingList2 :: (a0 -> Encoding) -> ([a0] -> Encoding) -> (b0 -> Encoding) -> ([b0] -> Encoding) -> [(a, b, c, d, e, f, g, h, a0, b0)] -> Encoding Source # | |
| (ToJSON a, ToJSON b, ToJSON c, ToJSON d, ToJSON e, ToJSON f, ToJSON g, ToJSON h, ToJSON i) => ToJSON2 ((,,,,,,,,,,) a b c d e f g h i) | |
Defined in Data.Aeson.Types.ToJSON Methods liftToJSON2 :: (a0 -> Value) -> ([a0] -> Value) -> (b0 -> Value) -> ([b0] -> Value) -> (a, b, c, d, e, f, g, h, i, a0, b0) -> Value Source # liftToJSONList2 :: (a0 -> Value) -> ([a0] -> Value) -> (b0 -> Value) -> ([b0] -> Value) -> [(a, b, c, d, e, f, g, h, i, a0, b0)] -> Value Source # liftToEncoding2 :: (a0 -> Encoding) -> ([a0] -> Encoding) -> (b0 -> Encoding) -> ([b0] -> Encoding) -> (a, b, c, d, e, f, g, h, i, a0, b0) -> Encoding Source # liftToEncodingList2 :: (a0 -> Encoding) -> ([a0] -> Encoding) -> (b0 -> Encoding) -> ([b0] -> Encoding) -> [(a, b, c, d, e, f, g, h, i, a0, b0)] -> Encoding Source # | |
| (ToJSON a, ToJSON b, ToJSON c, ToJSON d, ToJSON e, ToJSON f, ToJSON g, ToJSON h, ToJSON i, ToJSON j) => ToJSON2 ((,,,,,,,,,,,) a b c d e f g h i j) | |
Defined in Data.Aeson.Types.ToJSON Methods liftToJSON2 :: (a0 -> Value) -> ([a0] -> Value) -> (b0 -> Value) -> ([b0] -> Value) -> (a, b, c, d, e, f, g, h, i, j, a0, b0) -> Value Source # liftToJSONList2 :: (a0 -> Value) -> ([a0] -> Value) -> (b0 -> Value) -> ([b0] -> Value) -> [(a, b, c, d, e, f, g, h, i, j, a0, b0)] -> Value Source # liftToEncoding2 :: (a0 -> Encoding) -> ([a0] -> Encoding) -> (b0 -> Encoding) -> ([b0] -> Encoding) -> (a, b, c, d, e, f, g, h, i, j, a0, b0) -> Encoding Source # liftToEncodingList2 :: (a0 -> Encoding) -> ([a0] -> Encoding) -> (b0 -> Encoding) -> ([b0] -> Encoding) -> [(a, b, c, d, e, f, g, h, i, j, a0, b0)] -> Encoding Source # | |
| (ToJSON a, ToJSON b, ToJSON c, ToJSON d, ToJSON e, ToJSON f, ToJSON g, ToJSON h, ToJSON i, ToJSON j, ToJSON k) => ToJSON2 ((,,,,,,,,,,,,) a b c d e f g h i j k) | |
Defined in Data.Aeson.Types.ToJSON Methods liftToJSON2 :: (a0 -> Value) -> ([a0] -> Value) -> (b0 -> Value) -> ([b0] -> Value) -> (a, b, c, d, e, f, g, h, i, j, k, a0, b0) -> Value Source # liftToJSONList2 :: (a0 -> Value) -> ([a0] -> Value) -> (b0 -> Value) -> ([b0] -> Value) -> [(a, b, c, d, e, f, g, h, i, j, k, a0, b0)] -> Value Source # liftToEncoding2 :: (a0 -> Encoding) -> ([a0] -> Encoding) -> (b0 -> Encoding) -> ([b0] -> Encoding) -> (a, b, c, d, e, f, g, h, i, j, k, a0, b0) -> Encoding Source # liftToEncodingList2 :: (a0 -> Encoding) -> ([a0] -> Encoding) -> (b0 -> Encoding) -> ([b0] -> Encoding) -> [(a, b, c, d, e, f, g, h, i, j, k, a0, b0)] -> Encoding Source # | |
| (ToJSON a, ToJSON b, ToJSON c, ToJSON d, ToJSON e, ToJSON f, ToJSON g, ToJSON h, ToJSON i, ToJSON j, ToJSON k, ToJSON l) => ToJSON2 ((,,,,,,,,,,,,,) a b c d e f g h i j k l) | |
Defined in Data.Aeson.Types.ToJSON Methods liftToJSON2 :: (a0 -> Value) -> ([a0] -> Value) -> (b0 -> Value) -> ([b0] -> Value) -> (a, b, c, d, e, f, g, h, i, j, k, l, a0, b0) -> Value Source # liftToJSONList2 :: (a0 -> Value) -> ([a0] -> Value) -> (b0 -> Value) -> ([b0] -> Value) -> [(a, b, c, d, e, f, g, h, i, j, k, l, a0, b0)] -> Value Source # liftToEncoding2 :: (a0 -> Encoding) -> ([a0] -> Encoding) -> (b0 -> Encoding) -> ([b0] -> Encoding) -> (a, b, c, d, e, f, g, h, i, j, k, l, a0, b0) -> Encoding Source # liftToEncodingList2 :: (a0 -> Encoding) -> ([a0] -> Encoding) -> (b0 -> Encoding) -> ([b0] -> Encoding) -> [(a, b, c, d, e, f, g, h, i, j, k, l, a0, b0)] -> Encoding Source # | |
| (ToJSON a, ToJSON b, ToJSON c, ToJSON d, ToJSON e, ToJSON f, ToJSON g, ToJSON h, ToJSON i, ToJSON j, ToJSON k, ToJSON l, ToJSON m) => ToJSON2 ((,,,,,,,,,,,,,,) a b c d e f g h i j k l m) | |
Defined in Data.Aeson.Types.ToJSON Methods liftToJSON2 :: (a0 -> Value) -> ([a0] -> Value) -> (b0 -> Value) -> ([b0] -> Value) -> (a, b, c, d, e, f, g, h, i, j, k, l, m, a0, b0) -> Value Source # liftToJSONList2 :: (a0 -> Value) -> ([a0] -> Value) -> (b0 -> Value) -> ([b0] -> Value) -> [(a, b, c, d, e, f, g, h, i, j, k, l, m, a0, b0)] -> Value Source # liftToEncoding2 :: (a0 -> Encoding) -> ([a0] -> Encoding) -> (b0 -> Encoding) -> ([b0] -> Encoding) -> (a, b, c, d, e, f, g, h, i, j, k, l, m, a0, b0) -> Encoding Source # liftToEncodingList2 :: (a0 -> Encoding) -> ([a0] -> Encoding) -> (b0 -> Encoding) -> ([b0] -> Encoding) -> [(a, b, c, d, e, f, g, h, i, j, k, l, m, a0, b0)] -> Encoding Source # | |
fromEncoding :: Encoding' tag -> Builder Source #
Acquire the underlying bytestring builder.
A series of values that, when encoded, should be separated by
commas. Since 0.11.0.0, the .= operator is overloaded to create
either (Text, Value) or Series. You can use Series when
encoding directly to a bytestring builder as in the following
example:
toEncoding (Person name age) = pairs ("name" .= name <> "age" .= age)(.!=) :: Parser (Maybe a) -> a -> Parser a Source #
Helper for use in combination with .:? to provide default
values for optional JSON object fields.
This combinator is most useful if the key and value can be absent
from an object without affecting its validity and we know a default
value to assign in that case. If the key and value are mandatory,
use .: instead.
Example usage:
v1 <- o.:?"opt_field_with_dfl" .!= "default_val" v2 <- o.:"mandatory_field" v3 <- o.:?"opt_field2"
fromJSON :: FromJSON a => Value -> Result a Source #
Convert a value from JSON, failing if the types do not match.
withEmbeddedJSON :: String -> (Value -> Parser a) -> Value -> Parser a Source #
Decode a nested JSON-encoded string.
withScientific :: String -> (Scientific -> Parser a) -> Value -> Parser a Source #
withScientific name f valuef to the Scientific number
when value is a Number and fails using typeMismatch
otherwise.
Warning: If you are converting from a scientific to an unbounded
type such as Integer you may want to add a restriction on the
size of the exponent (see withBoundedScientific) to prevent
malicious input from filling up the memory of the target system.
Error message example
withScientific "MyType" f (String "oops") -- Error: "parsing MyType failed, expected Number, but encountered String"
withObject :: String -> (Object -> Parser a) -> Value -> Parser a Source #
withObject name f valuef to the Object when value
is an Object and fails otherwise.
Error message example
withObject "MyType" f (String "oops") -- Error: "parsing MyType failed, expected Object, but encountered String"
parseJSON2 :: (FromJSON2 f, FromJSON a, FromJSON b) => Value -> Parser (f a b) Source #
Lift the standard parseJSON function through the type constructor.
parseJSON1 :: (FromJSON1 f, FromJSON a) => Value -> Parser (f a) Source #
Lift the standard parseJSON function through the type constructor.
genericFromJSONKey :: (Generic a, GFromJSONKey (Rep a)) => JSONKeyOptions -> FromJSONKeyFunction a Source #
fromJSONKey for Generic types.
These types must be sums of nullary constructors, whose names will be used
as keys for JSON objects.
See also genericToJSONKey.
Example
data Color = Red | Green | Blue derivingGenericinstanceFromJSONKeyColor wherefromJSONKey=genericFromJSONKeydefaultJSONKeyOptions
genericLiftParseJSON :: (Generic1 f, GFromJSON One (Rep1 f)) => Options -> (Value -> Parser a) -> (Value -> Parser [a]) -> Value -> Parser (f a) Source #
A configurable generic JSON decoder. This function applied to
defaultOptions is used as the default for liftParseJSON when the
type is an instance of Generic1.
genericParseJSON :: (Generic a, GFromJSON Zero (Rep a)) => Options -> Value -> Parser a Source #
A configurable generic JSON decoder. This function applied to
defaultOptions is used as the default for parseJSON when the
type is an instance of Generic.
class GFromJSON arity (f :: Type -> Type) where Source #
Class of generic representation types that can be converted from JSON.
Methods
gParseJSON :: Options -> FromArgs arity a -> Value -> Parser (f a) Source #
This method (applied to defaultOptions) is used as the
default generic implementation of parseJSON (if the arity is Zero)
or liftParseJSON (if the arity is One).
Instances
| GFromJSON One Par1 | |
Defined in Data.Aeson.Types.FromJSON | |
| GFromJSON arity (V1 :: Type -> Type) | |
Defined in Data.Aeson.Types.FromJSON | |
| FromJSON1 f => GFromJSON One (Rec1 f) | |
Defined in Data.Aeson.Types.FromJSON | |
| (GFromJSON' arity a, Datatype d) => GFromJSON arity (D1 d a) | |
Defined in Data.Aeson.Types.FromJSON | |
| FromJSON a => GFromJSON arity (K1 i a :: Type -> Type) | |
Defined in Data.Aeson.Types.FromJSON | |
| GFromJSON arity a => GFromJSON arity (M1 i c a) | |
Defined in Data.Aeson.Types.FromJSON | |
| (FromJSON1 f, GFromJSON One g) => GFromJSON One (f :.: g) | |
Defined in Data.Aeson.Types.FromJSON | |
class FromJSON a where Source #
A type that can be converted from JSON, with the possibility of failure.
In many cases, you can get the compiler to generate parsing code for you (see below). To begin, let's cover writing an instance by hand.
There are various reasons a conversion could fail. For example, an
Object could be missing a required key, an Array could be of
the wrong size, or a value could be of an incompatible type.
The basic ways to signal a failed conversion are as follows:
failyields a custom error message: it is the recommended way of reporting a failure;empty(ormzero) is uninformative: use it when the error is meant to be caught by some(;<|>)typeMismatchcan be used to report a failure when the encountered value is not of the expected JSON type;unexpectedis an appropriate alternative when more than one type may be expected, or to keep the expected type implicit.
prependFailure (or modifyFailure) add more information to a parser's
error messages.
An example type and instance using typeMismatch and prependFailure:
-- Allow ourselves to writeTextliterals. {-# LANGUAGE OverloadedStrings #-} data Coord = Coord { x :: Double, y :: Double } instanceFromJSONCoord whereparseJSON(Objectv) = Coord<$>v.:"x"<*>v.:"y" -- We do not expect a non-Objectvalue here. -- We could useemptyto fail, buttypeMismatch-- gives a much more informative error message.parseJSONinvalid =prependFailure"parsing Coord failed, " (typeMismatch"Object" invalid)
For this common case of only being concerned with a single
type of JSON value, the functions withObject, withScientific, etc.
are provided. Their use is to be preferred when possible, since
they are more terse. Using withObject, we can rewrite the above instance
(assuming the same language extension and data type) as:
instanceFromJSONCoord whereparseJSON=withObject"Coord" $ \v -> Coord<$>v.:"x"<*>v.:"y"
Instead of manually writing your FromJSON instance, there are two options
to do it automatically:
- Data.Aeson.TH provides Template Haskell functions which will derive an instance at compile time. The generated instance is optimized for your type so it will probably be more efficient than the following option.
- The compiler can provide a default generic implementation for
parseJSON.
To use the second, simply add a deriving clause to your
datatype and declare a GenericFromJSON instance for your datatype without giving
a definition for parseJSON.
For example, the previous example can be simplified to just:
{-# LANGUAGE DeriveGeneric #-}
import GHC.Generics
data Coord = Coord { x :: Double, y :: Double } deriving Generic
instance FromJSON Coord
The default implementation will be equivalent to
parseJSON = ; if you need different
options, you can customize the generic decoding by defining:genericParseJSON defaultOptions
customOptions =defaultOptions{fieldLabelModifier=maptoUpper} instanceFromJSONCoord whereparseJSON=genericParseJSONcustomOptions
Minimal complete definition
Nothing
Instances
class FromJSONKey a where Source #
Read the docs for ToJSONKey first. This class is a conversion
in the opposite direction. If you have a newtype wrapper around Text,
the recommended way to define instances is with generalized newtype deriving:
newtype SomeId = SomeId { getSomeId :: Text }
deriving (Eq,Ord,Hashable,FromJSONKey)If you have a sum of nullary constructors, you may use the generic implementation:
data Color = Red | Green | Blue deriving Generic instanceFromJSONKeyColor wherefromJSONKey=genericFromJSONKeydefaultJSONKeyOptions
Minimal complete definition
Nothing
Methods
fromJSONKey :: FromJSONKeyFunction a Source #
Strategy for parsing the key of a map-like container.
Instances
data FromJSONKeyFunction a Source #
This type is related to ToJSONKeyFunction. If FromJSONKeyValue is used in the
FromJSONKey instance, then ToJSONKeyValue should be used in the ToJSONKey
instance. The other three data constructors for this type all correspond to
ToJSONKeyText. Strictly speaking, FromJSONKeyTextParser is more powerful than
FromJSONKeyText, which is in turn more powerful than FromJSONKeyCoerce.
For performance reasons, these exist as three options instead of one.
Constructors
| FromJSONKeyCoerce !(CoerceText a) | uses |
| FromJSONKeyText !(Text -> a) | conversion from |
| FromJSONKeyTextParser !(Text -> Parser a) | conversion from |
| FromJSONKeyValue !(Value -> Parser a) | conversion for non-textual keys |
Instances
| Functor FromJSONKeyFunction | Only law abiding up to interpretation |
Defined in Data.Aeson.Types.FromJSON Methods fmap :: (a -> b) -> FromJSONKeyFunction a -> FromJSONKeyFunction b Source # (<$) :: a -> FromJSONKeyFunction b -> FromJSONKeyFunction a Source # | |
class (ConstructorNames f, SumFromString f) => GFromJSONKey (f :: Type -> Type) Source #
Instances
| (ConstructorNames f, SumFromString f) => GFromJSONKey f | |
Defined in Data.Aeson.Types.FromJSON | |
class FromJSON1 (f :: Type -> Type) where Source #
Lifting of the FromJSON class to unary type constructors.
Instead of manually writing your FromJSON1 instance, there are two options
to do it automatically:
- Data.Aeson.TH provides Template Haskell functions which will derive an instance at compile time. The generated instance is optimized for your type so it will probably be more efficient than the following option.
- The compiler can provide a default generic implementation for
liftParseJSON.
To use the second, simply add a deriving clause to your
datatype and declare a Generic1FromJSON1 instance for your datatype without giving
a definition for liftParseJSON.
For example:
{-# LANGUAGE DeriveGeneric #-}
import GHC.Generics
data Pair a b = Pair { pairFst :: a, pairSnd :: b } deriving Generic1
instance FromJSON a => FromJSON1 (Pair a)
If the default implementation doesn't give exactly the results you want,
you can customize the generic decoding with only a tiny amount of
effort, using genericLiftParseJSON with your preferred Options:
customOptions =defaultOptions{fieldLabelModifier=maptoUpper} instanceFromJSONa =>FromJSON1(Pair a) whereliftParseJSON=genericLiftParseJSONcustomOptions
Minimal complete definition
Nothing
Methods
liftParseJSON :: (Value -> Parser a) -> (Value -> Parser [a]) -> Value -> Parser (f a) Source #
liftParseJSONList :: (Value -> Parser a) -> (Value -> Parser [a]) -> Value -> Parser [f a] Source #
Instances
class FromJSON2 (f :: Type -> Type -> Type) where Source #
Lifting of the FromJSON class to binary type constructors.
Instead of manually writing your FromJSON2 instance, Data.Aeson.TH
provides Template Haskell functions which will derive an instance at compile time.
Minimal complete definition
Methods
liftParseJSON2 :: (Value -> Parser a) -> (Value -> Parser [a]) -> (Value -> Parser b) -> (Value -> Parser [b]) -> Value -> Parser (f a b) Source #
liftParseJSONList2 :: (Value -> Parser a) -> (Value -> Parser [a]) -> (Value -> Parser b) -> (Value -> Parser [b]) -> Value -> Parser [f a b] Source #
Instances
json' :: Parser Value Source #
Parse any JSON value.
This is a strict version of json which avoids building up thunks
during parsing; it performs all conversions immediately. Prefer
this version if most of the JSON data needs to be accessed.
This function is an alias for value'. In aeson 0.8 and earlier, it
parsed only object or array types, in conformance with the
now-obsolete RFC 4627.
Warning
If an object contains duplicate keys, only the first one will be kept.
For a more flexible alternative, see jsonWith'.
Parse any JSON value.
The conversion of a parsed value to a Haskell value is deferred until the Haskell value is needed. This may improve performance if only a subset of the results of conversions are needed, but at a cost in thunk allocation.
This function is an alias for value. In aeson 0.8 and earlier, it
parsed only object or array types, in conformance with the
now-obsolete RFC 4627.
Warning
If an object contains duplicate keys, only the first one will be kept.
For a more flexible alternative, see jsonWith.
camelTo2 :: Char -> String -> String Source #
Better version of camelTo. Example where it works better:
camelTo '_' 'CamelAPICase' == "camel_apicase" camelTo2 '_' 'CamelAPICase' == "camel_api_case"
defaultJSONKeyOptions :: JSONKeyOptions Source #
Default JSONKeyOptions:
defaultJSONKeyOptions =JSONKeyOptions{keyModifier=id}
defaultTaggedObject :: SumEncoding Source #
Default TaggedObject SumEncoding options:
defaultTaggedObject =TaggedObject{tagFieldName= "tag" ,contentsFieldName= "contents" }
defaultOptions :: Options Source #
Default encoding Options:
Options{fieldLabelModifier= id ,constructorTagModifier= id ,allNullaryToStringTag= True ,omitNothingFields= False ,sumEncoding=defaultTaggedObject,unwrapUnaryRecords= False ,tagSingleConstructors= False ,rejectUnknownFields= False }
(<?>) :: Parser a -> JSONPathElement -> Parser a Source #
Add JSON Path context to a parser
When parsing a complex structure, it helps to annotate (sub)parsers with context, so that if an error occurs, you can find its location.
withObject "Person" $ \o ->
Person
<$> o .: "name" <?> Key "name"
<*> o .: "age" <?> Key "age"(Standard methods like (.:) already do this.)
With such annotations, if an error occurs, you will get a JSON Path location of that error.
Since 0.10
type JSONPath = [JSONPathElement] Source #
The result of running a Parser.
Instances
A JSON value represented as a Haskell value.
Instances
| Eq Value | |
| Data Value | |
Defined in Data.Aeson.Types.Internal Methods gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Value -> c Value Source # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c Value Source # toConstr :: Value -> Constr Source # dataTypeOf :: Value -> DataType Source # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c Value) Source # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c Value) Source # gmapT :: (forall b. Data b => b -> b) -> Value -> Value Source # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Value -> r Source # gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Value -> r Source # gmapQ :: (forall d. Data d => d -> u) -> Value -> [u] Source # gmapQi :: Int -> (forall d. Data d => d -> u) -> Value -> u Source # gmapM :: Monad m => (forall d. Data d => d -> m d) -> Value -> m Value Source # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Value -> m Value Source # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Value -> m Value Source # | |
| Read Value | |
| Show Value | |
| IsString Value | |
Defined in Data.Aeson.Types.Internal Methods fromString :: String -> Value Source # | |
| Generic Value | |
| Lift Value | |
| NFData Value | |
Defined in Data.Aeson.Types.Internal | |
| Hashable Value | |
Defined in Data.Aeson.Types.Internal | |
| ToJSON Value | |
| KeyValue Object | Constructs a singleton |
| KeyValue Pair | |
| FromJSON Value | |
| FromString Encoding | |
Defined in Data.Aeson.Types.ToJSON Methods fromString :: String -> Encoding | |
| FromString Value | |
Defined in Data.Aeson.Types.ToJSON Methods fromString :: String -> Value | |
| GToJSON Encoding arity (U1 :: Type -> Type) | |
| GToJSON Value arity (V1 :: Type -> Type) | |
| GToJSON Value arity (U1 :: Type -> Type) | |
| ToJSON1 f => GToJSON Encoding One (Rec1 f) | |
| ToJSON1 f => GToJSON Value One (Rec1 f) | |
| ToJSON a => GToJSON Encoding arity (K1 i a :: Type -> Type) | |
| (EncodeProduct arity a, EncodeProduct arity b) => GToJSON Encoding arity (a :*: b) | |
| ToJSON a => GToJSON Value arity (K1 i a :: Type -> Type) | |
| (WriteProduct arity a, WriteProduct arity b, ProductSize a, ProductSize b) => GToJSON Value arity (a :*: b) | |
| (ToJSON1 f, GToJSON Encoding One g) => GToJSON Encoding One (f :.: g) | |
| (ToJSON1 f, GToJSON Value One g) => GToJSON Value One (f :.: g) | |
| FromPairs Value (DList Pair) | |
Defined in Data.Aeson.Types.ToJSON | |
| v ~ Value => KeyValuePair v (DList Pair) | |
Defined in Data.Aeson.Types.ToJSON | |
| (GToJSON Encoding arity a, ConsToJSON Encoding arity a, Constructor c) => SumToJSON' TwoElemArray Encoding arity (C1 c a) | |
Defined in Data.Aeson.Types.ToJSON | |
| (GToJSON Value arity a, ConsToJSON Value arity a, Constructor c) => SumToJSON' TwoElemArray Value arity (C1 c a) | |
Defined in Data.Aeson.Types.ToJSON | |
| type Rep Value | |
Defined in Data.Aeson.Types.Internal type Rep Value = D1 ('MetaData "Value" "Data.Aeson.Types.Internal" "aeson-1.4.7.1-LcFT4XRNxNk1GX4d6qN7FX" 'False) ((C1 ('MetaCons "Object" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'SourceStrict 'DecidedStrict) (Rec0 Object)) :+: (C1 ('MetaCons "Array" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'SourceStrict 'DecidedStrict) (Rec0 Array)) :+: C1 ('MetaCons "String" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'SourceStrict 'DecidedStrict) (Rec0 Text)))) :+: (C1 ('MetaCons "Number" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'SourceStrict 'DecidedStrict) (Rec0 Scientific)) :+: (C1 ('MetaCons "Bool" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'SourceStrict 'DecidedStrict) (Rec0 Bool)) :+: C1 ('MetaCons "Null" 'PrefixI 'False) (U1 :: Type -> Type)))) | |
newtype DotNetTime Source #
A newtype wrapper for UTCTime that uses the same non-standard
serialization format as Microsoft .NET, whose
System.DateTime
type is by default serialized to JSON as in the following example:
/Date(1302547608878)/
The number represents milliseconds since the Unix epoch.
Constructors
| DotNetTime | |
Fields
| |
Instances
Options that specify how to encode/decode your datatype to/from JSON.
Options can be set using record syntax on defaultOptions with the fields
below.
data SumEncoding Source #
Specifies how to encode constructors of a sum datatype.
Constructors
| TaggedObject | A constructor will be encoded to an object with a field
|
Fields | |
| UntaggedValue | Constructor names won't be encoded. Instead only the contents of the constructor will be encoded as if the type had a single constructor. JSON encodings have to be disjoint for decoding to work properly. When decoding, constructors are tried in the order of definition. If some encodings overlap, the first one defined will succeed. Note: Nullary constructors are encoded as strings (using
Note: Only the last error is kept when decoding, so in the case of malformed JSON, only an error for the last constructor will be reported. |
| ObjectWithSingleField | A constructor will be encoded to an object with a single
field named after the constructor tag (modified by the
|
| TwoElemArray | A constructor will be encoded to a 2-element array where the
first element is the tag of the constructor (modified by the
|
Instances
| Eq SumEncoding | |
Defined in Data.Aeson.Types.Internal Methods (==) :: SumEncoding -> SumEncoding -> Bool Source # (/=) :: SumEncoding -> SumEncoding -> Bool Source # | |
| Show SumEncoding | |
Defined in Data.Aeson.Types.Internal | |
data JSONKeyOptions Source #
Options for encoding keys with genericFromJSONKey and
genericToJSONKey.
A type-level indicator that ToJSON1 or FromJSON1 is being derived generically.
Instances
| GFromJSON One Par1 | |
Defined in Data.Aeson.Types.FromJSON | |
| GToJSON enc One Par1 | |
| ToJSON1 f => GToJSON Encoding One (Rec1 f) | |
| ToJSON1 f => GToJSON Value One (Rec1 f) | |
| (ToJSON1 f, GToJSON Encoding One g) => GToJSON Encoding One (f :.: g) | |
| (ToJSON1 f, GToJSON Value One g) => GToJSON Value One (f :.: g) | |
| FromJSON1 f => GFromJSON One (Rec1 f) | |
Defined in Data.Aeson.Types.FromJSON | |
| (FromJSON1 f, GFromJSON One g) => GFromJSON One (f :.: g) | |
Defined in Data.Aeson.Types.FromJSON | |
Extended failure messages
(.:?) :: FromJSON a => Object -> Text -> Parser (Maybe a) Source #
Extends .:? warning to include field name.
JSON Parser that emits warnings
data JSONWarning Source #
Warning output from WarningParser.
Constructors
| JSONUnrecognizedFields String [Text] | |
| JSONGeneralWarning !Text |
Instances
| Eq JSONWarning Source # | |
Defined in Pantry.Internal.AesonExtended Methods (==) :: JSONWarning -> JSONWarning -> Bool Source # (/=) :: JSONWarning -> JSONWarning -> Bool Source # | |
| Show JSONWarning Source # | |
Defined in Pantry.Internal.AesonExtended | |
| IsString JSONWarning Source # | |
Defined in Pantry.Internal.AesonExtended Methods fromString :: String -> JSONWarning Source # | |
| Display JSONWarning Source # | |
Defined in Pantry.Internal.AesonExtended | |
type WarningParser a = WriterT WarningParserMonoid Parser a Source #
JSON parser that warns about unexpected fields in objects.
data WithJSONWarnings a Source #
Constructors
| WithJSONWarnings a [JSONWarning] |
Instances
withObjectWarnings :: String -> (Object -> WarningParser a) -> Value -> Parser (WithJSONWarnings a) Source #
WarningParser version of withObject.
jsonSubWarnings :: WarningParser (WithJSONWarnings a) -> WarningParser a Source #
Handle warnings in a sub-object.
jsonSubWarningsT :: Traversable t => WarningParser (t (WithJSONWarnings a)) -> WarningParser (t a) Source #
Handle warnings in a Traversable of sub-objects.
jsonSubWarningsTT :: (Traversable t, Traversable u) => WarningParser (u (t (WithJSONWarnings a))) -> WarningParser (u (t a)) Source #
Handle warnings in a Maybe Traversable of sub-objects.
logJSONWarnings :: (MonadReader env m, HasLogFunc env, HasCallStack, MonadIO m) => FilePath -> [JSONWarning] -> m () Source #
Log JSON warnings.
noJSONWarnings :: a -> WithJSONWarnings a Source #
tellJSONField :: Text -> WarningParser () Source #
Tell warning parser about an expected field, so it doesn't warn about it.
unWarningParser :: WarningParser a -> Parser a Source #
Convert a WarningParser to a Parser.
(..:) :: FromJSON a => Object -> Text -> WarningParser a Source #
WarningParser version of .:.
(..:?) :: FromJSON a => Object -> Text -> WarningParser (Maybe a) Source #
WarningParser version of .:?.
(...:?) :: FromJSON a => Object -> [Text] -> WarningParser (Maybe a) Source #
Synonym version of ..:?.
(..!=) :: WarningParser (Maybe a) -> a -> WarningParser a Source #
WarningParser version of .!=.