Safe Haskell | None |
---|---|
Language | Haskell98 |
Yesod.Core.Json
Synopsis
- defaultLayoutJson :: (Yesod site, ToJSON a) => WidgetFor site () -> HandlerFor site a -> HandlerFor site TypedContent
- jsonToRepJson :: (Monad m, ToJSON a) => a -> m Value
- returnJson :: (Monad m, ToJSON a) => a -> m Value
- returnJsonEncoding :: (Monad m, ToJSON a) => a -> m Encoding
- provideJson :: (Monad m, ToJSON a) => a -> Writer (Endo [ProvidedRep m]) ()
- parseCheckJsonBody :: (MonadHandler m, FromJSON a) => m (Result a)
- parseInsecureJsonBody :: (MonadHandler m, FromJSON a) => m (Result a)
- requireCheckJsonBody :: (MonadHandler m, FromJSON a) => m a
- requireInsecureJsonBody :: (MonadHandler m, FromJSON a) => m a
- parseJsonBody :: (MonadHandler m, FromJSON a) => m (Result a)
- parseJsonBody_ :: (MonadHandler m, FromJSON a) => m a
- requireJsonBody :: (MonadHandler m, FromJSON a) => m a
- data Value
- class ToJSON a where
- toJSON :: a -> Value
- toEncoding :: a -> Encoding
- toJSONList :: [a] -> Value
- toEncodingList :: [a] -> Encoding
- class FromJSON a where
- array :: ToJSON a => [a] -> Value
- object :: [Pair] -> Value
- (.=) :: (KeyValue kv, ToJSON v) => Text -> v -> kv
- (.:) :: FromJSON a => Object -> Text -> Parser a
- jsonOrRedirect :: (MonadHandler m, ToJSON a) => Route (HandlerSite m) -> a -> m Value
- jsonEncodingOrRedirect :: (MonadHandler m, ToJSON a) => Route (HandlerSite m) -> a -> m Encoding
- acceptsJson :: MonadHandler m => m Bool
- contentTypeHeaderIsJson :: ByteString -> Bool
Convert from a JSON value
Arguments
:: (Yesod site, ToJSON a) | |
=> WidgetFor site () | HTML |
-> HandlerFor site a | JSON |
-> HandlerFor site TypedContent |
Provide both an HTML and JSON representation for a piece of
data, using the default layout for the HTML output
(defaultLayout
).
Since: 0.3.0
jsonToRepJson :: (Monad m, ToJSON a) => a -> m Value Source #
Deprecated: Use returnJson instead
Wraps a data type in a RepJson
. The data type must
support conversion to JSON via ToJSON
.
Since: 0.3.0
returnJson :: (Monad m, ToJSON a) => a -> m Value Source #
Convert a value to a JSON representation via aeson's toJSON
function.
Since: 1.2.1
returnJsonEncoding :: (Monad m, ToJSON a) => a -> m Encoding Source #
Convert a value to a JSON representation via aeson's toEncoding
function.
Since: 1.4.21
provideJson :: (Monad m, ToJSON a) => a -> Writer (Endo [ProvidedRep m]) () Source #
Provide a JSON representation for usage with selectReps
, using aeson's
toJSON
(aeson >= 0.11: toEncoding
) function to perform the conversion.
Since: 1.2.1
Convert to a JSON value
parseCheckJsonBody :: (MonadHandler m, FromJSON a) => m (Result a) Source #
Parse the request body to a data type as a JSON value. The
data type must support conversion from JSON via FromJSON
.
If you want the raw JSON value, just ask for a
.Result
Value
The MIME type must indicate JSON content. Requiring a JSON content-type helps secure your site against CSRF attacks (browsers will perform POST requests for form and text/plain content-types without doing a CORS check, and those content-types can easily contain valid JSON).
Note that this function will consume the request body. As such, calling it twice will result in a parse error on the second call, since the request body will no longer be available.
Since: 0.3.0
parseInsecureJsonBody :: (MonadHandler m, FromJSON a) => m (Result a) Source #
Same as parseCheckJsonBody
, but does not check that the mime type
indicates JSON content.
Note: This function is vulnerable to CSRF attacks.
Since: 1.6.11
requireCheckJsonBody :: (MonadHandler m, FromJSON a) => m a Source #
Same as parseCheckJsonBody
, but return an invalid args response on a parse
error.
requireInsecureJsonBody :: (MonadHandler m, FromJSON a) => m a Source #
Same as parseInsecureJsonBody
, but return an invalid args response on a parse
error.
Since: 1.6.11
Deprecated JSON conversion
parseJsonBody :: (MonadHandler m, FromJSON a) => m (Result a) Source #
Deprecated: Use parseCheckJsonBody or parseInsecureJsonBody instead
Same as parseInsecureJsonBody
Since: 0.3.0
parseJsonBody_ :: (MonadHandler m, FromJSON a) => m a Source #
Deprecated: Use requireCheckJsonBody or requireInsecureJsonBody instead
Same as parseInsecureJsonBody
, but return an invalid args response on a parse
error.
requireJsonBody :: (MonadHandler m, FromJSON a) => m a Source #
Deprecated: Use requireCheckJsonBody or requireInsecureJsonBody instead
Same as parseInsecureJsonBody
, but return an invalid args response on a parse
error.
Produce JSON values
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 gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c Value dataTypeOf :: Value -> DataType dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c Value) dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c Value) gmapT :: (forall b. Data b => b -> b) -> Value -> Value gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Value -> r gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Value -> r gmapQ :: (forall d. Data d => d -> u) -> Value -> [u] gmapQi :: Int -> (forall d. Data d => d -> u) -> Value -> u gmapM :: Monad m => (forall d. Data d => d -> m d) -> Value -> m Value gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Value -> m Value gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Value -> m Value | |
Read Value | |
Defined in Data.Aeson.Types.Internal | |
Show Value | |
IsString Value | |
Defined in Data.Aeson.Types.Internal Methods fromString :: String -> Value | |
Generic Value | |
Lift 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 | |
NFData Value | |
Defined in Data.Aeson.Types.Internal | |
ToJavascript Value | |
Defined in Text.Julius Methods toJavascript :: Value -> Javascript Source # | |
FromString Encoding | |
Defined in Data.Aeson.Types.ToJSON Methods fromString :: String -> Encoding | |
FromString Value | |
Defined in Data.Aeson.Types.ToJSON Methods fromString :: String -> Value | |
ToTypedContent Encoding Source # | |
Defined in Yesod.Core.Content Methods | |
ToTypedContent Value Source # | |
Defined in Yesod.Core.Content Methods toTypedContent :: Value -> TypedContent Source # | |
HasContentType Encoding Source # | |
Defined in Yesod.Core.Content Methods getContentType :: Monad m => m Encoding -> ContentType Source # | |
HasContentType Value Source # | |
Defined in Yesod.Core.Content Methods getContentType :: Monad m => m Value -> ContentType Source # | |
ToContent Encoding Source # | |
ToContent Value Source # | |
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 Methods sumToJSON' :: Options -> ToArgs Encoding arity a0 -> C1 c a a0 -> Tagged TwoElemArray Encoding | |
(GToJSON Value arity a, ConsToJSON Value arity a, Constructor c) => SumToJSON' TwoElemArray Value arity (C1 c a) | |
Defined in Data.Aeson.Types.ToJSON Methods sumToJSON' :: Options -> ToArgs Value arity a0 -> C1 c a a0 -> Tagged TwoElemArray Value | |
type Rep Value | |
Defined in Data.Aeson.Types.Internal type Rep Value = D1 ('MetaData "Value" "Data.Aeson.Types.Internal" "aeson-1.4.7.1-4nEbPfB99jL2Y9NC3JxDd6" '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)))) |
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 writeText
literals. {-# LANGUAGE OverloadedStrings #-} data Coord = Coord { x :: Double, y :: Double } instanceToJSON
Coord 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 Generic
ToJSON
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 } derivingGeneric
instanceToJSON
Coord wheretoEncoding
=genericToEncoding
defaultOptions
If on the other hand you wish to customize the generic decoding, you have to implement both methods:
customOptions =defaultOptions
{fieldLabelModifier
=map
toUpper
} instanceToJSON
Coord wheretoJSON
=genericToJSON
customOptionstoEncoding
=genericToEncoding
customOptions
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
toJSON
is 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
toEncoding
still compile and have the correct semantics. This is ensured by making the default implementation oftoEncoding
usetoJSON
. 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 Coord
would be sufficient as a generically decoding instance, but there probably exists no good reason to not specifytoEncoding
in 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.
instanceToJSON
Coord wheretoEncoding
=genericToEncoding
defaultOptions
toJSONList :: [a] -> Value Source #
toEncodingList :: [a] -> Encoding Source #
Instances
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:
fail
yields 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(
;<|>
)typeMismatch
can be used to report a failure when the encountered value is not of the expected JSON type;unexpected
is 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 writeText
literals. {-# LANGUAGE OverloadedStrings #-} data Coord = Coord { x :: Double, y :: Double } instanceFromJSON
Coord whereparseJSON
(Object
v) = Coord<$>
v.:
"x"<*>
v.:
"y" -- We do not expect a non-Object
value here. -- We could useempty
to fail, buttypeMismatch
-- gives a much more informative error message.parseJSON
invalid =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:
instanceFromJSON
Coord 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 Generic
FromJSON
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 } derivingGeneric
instanceFromJSON
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
=map
toUpper
} instanceFromJSON
Coord whereparseJSON
=genericParseJSON
customOptions
Minimal complete definition
Nothing
Instances
FromJSON Bool | |
FromJSON Char | |
FromJSON Double | |
FromJSON Float | |
FromJSON Int | |
FromJSON Int8 | |
FromJSON Int16 | |
FromJSON Int32 | |
FromJSON Int64 | |
FromJSON Integer | This instance includes a bounds check to prevent maliciously
large inputs to fill up the memory of the target system. You can
newtype |
FromJSON Natural | |
FromJSON Ordering | |
FromJSON Word | |
FromJSON Word8 | |
FromJSON Word16 | |
FromJSON Word32 | |
FromJSON Word64 | |
FromJSON () | |
FromJSON Scientific | |
FromJSON Text | |
FromJSON UTCTime | |
FromJSON Value | |
FromJSON DotNetTime | |
Defined in Data.Aeson.Types.FromJSON Methods parseJSON :: Value -> Parser DotNetTime Source # parseJSONList :: Value -> Parser [DotNetTime] Source # | |
FromJSON Text | |
FromJSON Void | |
FromJSON DiffTime | This instance includes a bounds check to prevent maliciously
large inputs to fill up the memory of the target system. You can
newtype |
FromJSON CTime | |
FromJSON Version | |
FromJSON IntSet | |
FromJSON CalendarDiffDays | |
FromJSON Day | |
FromJSON DayOfWeek | |
FromJSON NominalDiffTime | This instance includes a bounds check to prevent maliciously
large inputs to fill up the memory of the target system. You can
newtype |
FromJSON CalendarDiffTime | |
FromJSON LocalTime | |
FromJSON TimeOfDay | |
FromJSON ZonedTime | Supported string formats:
The first space may instead be a |
FromJSON SystemTime | |
FromJSON UUID | |
FromJSON a => FromJSON [a] | |
FromJSON a => FromJSON (Maybe a) | |
(FromJSON a, Integral a) => FromJSON (Ratio a) | |
FromJSON a => FromJSON (Identity a) | |
FromJSON a => FromJSON (Dual a) | |
FromJSON a => FromJSON (Last a) | |
FromJSON a => FromJSON (First a) | |
(Prim a, FromJSON a) => FromJSON (PrimArray a) | |
FromJSON a => FromJSON (SmallArray a) | |
Defined in Data.Aeson.Types.FromJSON Methods parseJSON :: Value -> Parser (SmallArray a) Source # parseJSONList :: Value -> Parser [SmallArray a] Source # | |
FromJSON a => FromJSON (Array a) | |
(Eq a, Hashable a, FromJSON a) => FromJSON (HashSet a) | |
(Vector Vector a, FromJSON a) => FromJSON (Vector a) | |
(Storable a, FromJSON a) => FromJSON (Vector a) | |
(Prim a, FromJSON a) => FromJSON (Vector a) | |
FromJSON a => FromJSON (Vector a) | |
FromJSON a => FromJSON (NonEmpty a) | |
FromJSON a => FromJSON (IntMap a) | |
FromJSON a => FromJSON (Seq a) | |
(Ord a, FromJSON a) => FromJSON (Set a) | |
FromJSON v => FromJSON (Tree v) | |
HasResolution a => FromJSON (Fixed a) | This instance includes a bounds check to prevent maliciously
large inputs to fill up the memory of the target system. You can
newtype |
FromJSON a => FromJSON (First a) | |
FromJSON a => FromJSON (Last a) | |
FromJSON a => FromJSON (Max a) | |
FromJSON a => FromJSON (Min a) | |
FromJSON a => FromJSON (Option a) | |
FromJSON a => FromJSON (WrappedMonoid a) | |
FromJSON a => FromJSON (DList a) | |
(FromJSON a, FromJSON b) => FromJSON (Either a b) | |
(FromJSON a, FromJSON b) => FromJSON (a, b) | |
(FromJSON v, FromJSONKey k, Eq k, Hashable k) => FromJSON (HashMap k v) | |
(FromJSONKey k, Ord k, FromJSON v) => FromJSON (Map k v) | |
FromJSON (Proxy a) | |
(FromJSON a, FromJSON b, FromJSON c) => FromJSON (a, b, c) | |
FromJSON a => FromJSON (Const a b) | |
FromJSON b => FromJSON (Tagged a b) | |
(FromJSON a, FromJSON b, FromJSON c, FromJSON d) => FromJSON (a, b, c, d) | |
(FromJSON1 f, FromJSON1 g, FromJSON a) => FromJSON (Product f g a) | |
(FromJSON1 f, FromJSON1 g, FromJSON a) => FromJSON (Sum f g a) | |
(FromJSON a, FromJSON b, FromJSON c, FromJSON d, FromJSON e) => FromJSON (a, b, c, d, e) | |
(FromJSON1 f, FromJSON1 g, FromJSON a) => FromJSON (Compose f g a) | |
(FromJSON a, FromJSON b, FromJSON c, FromJSON d, FromJSON e, FromJSON f) => FromJSON (a, b, c, d, e, f) | |
(FromJSON a, FromJSON b, FromJSON c, FromJSON d, FromJSON e, FromJSON f, FromJSON g) => FromJSON (a, b, c, d, e, f, g) | |
(FromJSON a, FromJSON b, FromJSON c, FromJSON d, FromJSON e, FromJSON f, FromJSON g, FromJSON h) => FromJSON (a, b, c, d, e, f, g, h) | |
(FromJSON a, FromJSON b, FromJSON c, FromJSON d, FromJSON e, FromJSON f, FromJSON g, FromJSON h, FromJSON i) => FromJSON (a, b, c, d, e, f, g, h, i) | |
(FromJSON a, FromJSON b, FromJSON c, FromJSON d, FromJSON e, FromJSON f, FromJSON g, FromJSON h, FromJSON i, FromJSON j) => FromJSON (a, b, c, d, e, f, g, h, i, j) | |
(FromJSON a, FromJSON b, FromJSON c, FromJSON d, FromJSON e, FromJSON f, FromJSON g, FromJSON h, FromJSON i, FromJSON j, FromJSON k) => FromJSON (a, b, c, d, e, f, g, h, i, j, k) | |
(FromJSON a, FromJSON b, FromJSON c, FromJSON d, FromJSON e, FromJSON f, FromJSON g, FromJSON h, FromJSON i, FromJSON j, FromJSON k, FromJSON l) => FromJSON (a, b, c, d, e, f, g, h, i, j, k, l) | |
(FromJSON a, FromJSON b, FromJSON c, FromJSON d, FromJSON e, FromJSON f, FromJSON g, FromJSON h, FromJSON i, FromJSON j, FromJSON k, FromJSON l, FromJSON m) => FromJSON (a, b, c, d, e, f, g, h, i, j, k, l, m) | |
(FromJSON a, FromJSON b, FromJSON c, FromJSON d, FromJSON e, FromJSON f, FromJSON g, FromJSON h, FromJSON i, FromJSON j, FromJSON k, FromJSON l, FromJSON m, FromJSON n) => FromJSON (a, b, c, d, e, f, g, h, i, j, k, l, m, n) | |
(FromJSON a, FromJSON b, FromJSON c, FromJSON d, FromJSON e, FromJSON f, FromJSON g, FromJSON h, FromJSON i, FromJSON j, FromJSON k, FromJSON l, FromJSON m, FromJSON n, FromJSON o) => FromJSON (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o) | |
(.:) :: FromJSON a => Object -> Text -> 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.
Convenience functions
Arguments
:: (MonadHandler m, ToJSON a) | |
=> Route (HandlerSite m) | Redirect target |
-> a | Data to send via JSON |
-> m Value |
jsonOrRedirect simplifies the scenario where a POST handler sends a different response based on Accept headers:
- 200 with JSON data if the client prefers
application/json
(e.g. AJAX, seeacceptsJSON
). - 3xx otherwise, following the PRG pattern.
jsonEncodingOrRedirect Source #
Arguments
:: (MonadHandler m, ToJSON a) | |
=> Route (HandlerSite m) | Redirect target |
-> a | Data to send via JSON |
-> m Encoding |
jsonEncodingOrRedirect simplifies the scenario where a POST handler sends a different response based on Accept headers:
- 200 with JSON data if the client prefers
application/json
(e.g. AJAX, seeacceptsJSON
). - 3xx otherwise, following the PRG pattern. @since 1.4.21
acceptsJson :: MonadHandler m => m Bool Source #
Returns True
if the client prefers application/json
as
indicated by the Accept
HTTP header.
Checking if data is JSON
contentTypeHeaderIsJson :: ByteString -> Bool Source #
Given the Content-Type
header, returns if it is JSON.
This function is currently a simple check for application/json
, but in the future may check for
alternative representations such as xxx/yyy+json
.
Since: 1.6.17