# request

## Purpose

The `request` object is an instance of the Servlet API's HttpServletRequest class

## Examples

    class BookController {
    	def list = {
    		log.info "User agent: " + request.getHeader("User-Agent")		render(view:actionName)
    	}
    }

## Description

The HttpServletRequest class is useful for, amongst other things, obtaining request headers, storing request scoped attributes and establishing information about the client. Refer to the Servlet API's javadocs for further information.

Grails enhances the `HttpServletRequest` instance by adding the following new properties and methods:

- `XML` - An instance of `XmlSlurper`'s GPathResult class that allows parsing of an incoming XML request (useful for REST).
- `JSON` - An instance of Grails' JSONObject class that allows parsing of an incoming JSON request (useful for JSON based REST).
- `forwardURI` - Useful for obtaining the current request URI since the `request` objects `requestURI` property returns the original URI, not the matched one.
- `get` - Returns true if the current request is an HTTP `GET` request.
- `post` - Returns true if the current request is an HTTP `POST` request.
- `each` - Implementation of Groovy's `each` method for iterating over request attributes.
- `find` - Implementation of Groovy's default `find` method for searching request attributes.
- `findAll` - Implementation of Groovy's default `findAll` method for searching request attributes.
- `format` - The request format, used for content negotiation.

The `XML` and `JSON` properties are useful for XML APIs and can be used to parse incoming XML or JSON packages. For example given a request body of:

    <book>
       <title>The Stand</title>
    </book>

This can be parsed trivially:

    def title = request.XML?.book?.title
    render "The Title is $title"

Request attributes which are normally accessible via the getAttribute can also be indexed into using the array index operator or de-reference operator:

    def user = request['user']request['user'] = 'John'asset 'John' == request.user