Web.Respond.Types.Response

types and tools for making responses

responding

type Responder = Response -> IO ResponseReceived

the type of the responder callback that is handed to a WAI Application

response bodies.

type ResponseBody = (MediaType, ByteString)

contains both the content type header value and the body.

class ToResponseBody a where

instances of this class produce content-negotiated response bodies.

if you're in a situation where there are performance concerns around building a lazy bytestring for the response, you should consider instead building Responses by hand (i.e. by using the WAI functions).

Methods

toResponseBody

Arguments

:: a

the value to convert

-> ByteString

the http accept header. will be "*/*" if the client didn't set it.

-> Maybe ResponseBody

content type header, body

specify the conversion. this is supposed to fail if and only if there is no way for the instance to satisfy the accept header. otherwise. a successful conversion will include both a bytestring to use as the body and the value to use for the content type header

Instances

ToResponseBody Value

ToJSON a => ToResponseBody (JsonS a)

ToJSON a => ToResponseBody (Json a)

tools to build instances

type MediaTypeMatcher a = (MediaType, a -> ByteString)

pair of media type to match and a function that produces a builder for a value

prepMediaTypeMatcher :: a -> MediaTypeMatcher a -> (MediaType, ResponseBody)

converts a media type matcher into a pair of media type and response body...

yes, what it does is duplicate the media type and apply the builder to the value

matchToContentTypes :: [MediaTypeMatcher a] -> a -> ByteString -> Maybe ResponseBody

find the media type matcher that matches the passed Accept header value, and use it to produce a ResponseBuilder for the passed value. fail with Nothing if no builder can be found given the header. see prepMediaTypeMatcher

matchToContentTypesDefault :: MediaTypeMatcher a -> [MediaTypeMatcher a] -> a -> ByteString -> ResponseBody

try to match using matchToContents; if that fails, use the response body generated by the defaul matcher (first input)

charsetUtf8 :: (ByteString, ByteString)

the content type parameter charset=utf-8

textUtf8 :: MediaType -> (a -> Text) -> MediaTypeMatcher a

takes a text producer and produces a media type matcher that'll encode the text as utf-8 and annotate the content type with that parameter

you can use this in matchToContentTypes and render your type into lazy Text; this will make sure it gets encoded.

working with instances

mkResponseForBody :: Status -> ResponseHeaders -> ResponseBody -> Response

take a ResponseBody instance and turn it into a response

mkResponse :: ToResponseBody a => Status -> ResponseHeaders -> a -> ByteString -> Maybe Response

try to produce a Response object for an instance of ToResponseBody. the last input must be the value of the accept header

working with content types

JSON

jsonMatcher :: ToJSON a => MediaTypeMatcher a

make a MediaTypeMatcher that produces JSON

matchAcceptJson :: ToJSON a => a -> ByteString -> Maybe ResponseBody

matches only if client accepts "application/json"

renderable content types

HTML

htmlMatcher :: (a -> ByteString) -> MediaTypeMatcher a

builds an html matcher

matchAcceptHtml :: (a -> ByteString) -> a -> ByteString -> Maybe ResponseBody

matches only html acceptance

plaintext

textPlainMatcher :: (a -> ByteString) -> MediaTypeMatcher a

matchTextPlain :: (a -> ByteString) -> a -> ByteString -> Maybe ResponseBody