| Copyright | (c) 2011-2013 Bryan O'Sullivan (c) 2011 MailRank, Inc. |
|---|---|
| License | Apache |
| Maintainer | Bryan O'Sullivan <bos@serpentine.com> |
| Stability | experimental |
| Portability | portable |
| Safe Haskell | None |
| Language | Haskell98 |
JavaScript.JSON.Types.Instances
Description
Types for working with JSON data.
- class FromJSON a where
- class ToJSON a where
- class GFromJSON f where
- gParseJSON :: Options -> Value -> Parser (f a)
- class GToJSON f where
- genericToJSON :: (Generic a, GToJSON (Rep a)) => Options -> a -> Value
- genericParseJSON :: (Generic a, GFromJSON (Rep a)) => Options -> Value -> Parser a
- newtype DotNetTime :: * = DotNetTime {}
- withObject :: String -> (Object -> Parser a) -> Value -> Parser a
- withJSString :: String -> (JSString -> Parser a) -> Value -> Parser a
- withArray :: String -> (JSArray -> Parser a) -> Value -> Parser a
- withDouble :: String -> (Double -> Parser a) -> Value -> Parser a
- withBool :: String -> (Bool -> Parser a) -> Value -> Parser a
- fromJSON :: FromJSON a => Value -> Result a
- (.:) :: FromJSON a => Object -> JSString -> Parser a
- (.:?) :: FromJSON a => Object -> JSString -> Parser (Maybe a)
- (.!=) :: Parser (Maybe a) -> a -> Parser a
- (.=) :: ToJSON a => JSString -> a -> Pair
- typeMismatch :: String -> Value -> Parser a
Type classes
Core JSON classes
Minimal complete definition
Nothing
Generic JSON classes
Types
newtype DotNetTime :: *
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
| |
Inspecting Values
ValueswithObject :: String -> (Object -> Parser a) -> Value -> Parser a Source
withObject expected f value applies f to the Object when value is an Object
and fails using typeMismatch expected
withArray :: String -> (JSArray -> Parser a) -> Value -> Parser a Source
withArray expected f value applies f to the Array when value is an Array
and fails using typeMismatch expected
withDouble :: String -> (Double -> Parser a) -> Value -> Parser a Source
withScientific expected f value applies f to the Double number when value is a Number.
and fails using typeMismatch expected
withBool :: String -> (Bool -> Parser a) -> Value -> Parser a Source
withBool expected f value applies f to the Bool when value is a Bool
and fails using typeMismatch expected
Functions
fromJSON :: FromJSON a => Value -> Result a Source
Convert a value from JSON, failing if the types do not match.
(.:) :: FromJSON a => Object -> JSString -> Parser a Source
Retrieve the value associated with the given key of an Object.
The result is empty if the key is not present or the value cannot
be converted to the desired type.
This accessor is appropriate if the key and value must be present in an object for it to be valid. If the key and value are optional, use '(.:?)' instead.
(.:?) :: FromJSON a => Object -> JSString -> Parser (Maybe a) Source
Retrieve the value associated with the given key of an Object.
The result is Nothing if the key is not present, or empty if
the value cannot be converted to the desired type.
This accessor is most useful if the key and value can be absent from an object without affecting its validity. If the key and value are mandatory, use '(.:)' instead.
(.!=) :: 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"