yesod-json-1.1.2.1: Generate content for Yesod using the aeson package.

Safe HaskellNone

Yesod.Json

Contents

Synopsis

Convert from a JSON value

defaultLayoutJson

Arguments

:: (Yesod master, ToJSON a) 
=> GWidget sub master ()

HTML

-> a

JSON

-> GHandler sub master RepHtmlJson 

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 :: ToJSON a => a -> GHandler sub master RepJson

Wraps a data type in a RepJson. The data type must support conversion to JSON via ToJSON.

Since: 0.3.0

Convert to a JSON value

parseJsonBody :: FromJSON a => GHandler sub master (Result a)

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.

Since: 0.3.0

parseJsonBody_ :: FromJSON a => GHandler sub master a

Same as parseJsonBody, but return an invalid args response on a parse error.

Produce JSON values

data Value

A JSON value represented as a Haskell value.

Constructors

Object !Object 
Array !Array 
String !Text 
Number !Number 
Bool !Bool 
Null 

Instances

object :: ToJSON a => [(Text, a)] -> Value

Convert a list of pairs to an Object.

array :: ToJSON a => [a] -> Value

Convert a list of values to an Array.

(.=) :: ToJSON a => Text -> a -> Pair

Construct a Pair from a key and a value.

Convenience functions

jsonOrRedirect

Arguments

:: (Yesod master, ToJSON a) 
=> Route master

Redirect target

-> a

Data to send via JSON

-> GHandler sub master RepJson 

jsonOrRedirect simplifies the scenario where a POST handler sends a different response based on Accept headers:

  1. 200 with JSON data if the client prefers application/json (e.g. AJAX, see acceptsJSON).
  2. 3xx otherwise, following the PRG pattern.

acceptsJson :: Yesod master => GHandler sub master Bool

Returns True if the client prefers application/json as indicated by the Accept HTTP header.