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Request Handling

The Request Handler component is used in CakePHP to obtain additional information about the HTTP requests that are made to your applications. You can use it to inform your controllers about Ajax as well as gain additional insight into content types that the client accepts and automatically changes to the appropriate layout when file extensions are enabled.

By default RequestHandler will automatically detect Ajax requests based on the HTTP-X-Requested-With header that many javascript libraries use. When used in conjunction with Router::parseExtensions() RequestHandler will automatically switch the layout and view files to those that match the requested type. Furthermore, if a helper with the same name as the requested extension exists, it will be added to the Controllers Helper array. Lastly, if XML data is POST’ed to your Controllers, it will be parsed into an XML object which is assigned to Controller::data, and can then be saved as model data. In order to make use of Request Handler it must be included in your $components array.

<?php
class WidgetController extends AppController {

    var $components = array('RequestHandler');

    //rest of controller
}
?>

Obtaining Request Information

Request Handler has several methods that provide information about the client and its request.

accepts ( $type = null)

$type can be a string, or an array, or null. If a string, accepts will return true if the client accepts the content type. If an array is specified, accepts return true if any one of the content types is accepted by the client. If null returns an array of the content-types that the client accepts. For example:

class PostsController extends AppController {

    var $components = array('RequestHandler');

    function beforeFilter () {
        if ($this->RequestHandler->accepts('html')) {
            // Execute code only if client accepts an HTML (text/html) response
        } elseif ($this->RequestHandler->accepts('xml')) {
            // Execute XML-only code
        }
        if ($this->RequestHandler->accepts(array('xml', 'rss', 'atom'))) {
            // Executes if the client accepts any of the above: XML, RSS or Atom
        }
    }
}

Other request ‘type’ detection methods include:

isAjax()

Returns true if the request contains the X-Requested-Header equal to XMLHttpRequest.

isSSL()

Returns true if the current request was made over an SSL connection.

isXml()

Returns true if the current request accepts XML as a response.

isRss()

Returns true if the current request accepts RSS as a response.

isAtom()

Returns true if the current call accepts an Atom response, false otherwise.

isMobile()

Returns true if user agent string matches a mobile web browser, or if the client accepts WAP content. The supported Mobile User Agent strings are:

  • iPhone

  • MIDP

  • AvantGo

  • BlackBerry

  • J2ME

  • Opera Mini

  • DoCoMo

  • NetFront

  • Nokia

  • PalmOS

  • PalmSource

  • portalmmm

  • Plucker

  • ReqwirelessWeb

  • SonyEricsson

  • Symbian

  • UP.Browser

  • Windows CE

  • Xiino

isWap()

Returns true if the client accepts WAP content.

All of the above request detection methods can be used in a similar fashion to filter functionality intended for specific content types. For example when responding to Ajax requests, you often will want to disable browser caching, and change the debug level. However, you want to allow caching for non-ajax requests. The following would accomplish that:

if ($this->RequestHandler->isAjax()) {
    Configure::write('debug', 0);
    $this->header('Pragma: no-cache');
    $this->header('Cache-control: no-cache');
    $this->header("Expires: Mon, 26 Jul 1997 05:00:00 GMT");
}
//Continue Controller action

You could also disable caching with the functionally analogous Controller::disableCache

if ($this->RequestHandler->isAjax()) {
    $this->disableCache();
}
//Continue Controller action

Request Type Detection

RequestHandler also provides information about what type of HTTP request has been made and allowing you to respond to each Request Type.

isPost()

Returns true if the request is a POST request.

isPut()

Returns true if the request is a PUT request.

isGet()

Returns true if the request is a GET request.

isDelete()

Returns true if the request is a DELETE request.

Obtaining Additional Client Information

getClientIP()

Get the remote client IP address

getReferer()

Returns the domain name from which the request originated

getAjaxVersion()

Gets Prototype version if call is Ajax, otherwise empty string. The Prototype library sets a special “Prototype version” HTTP header.

Responding To Requests

In addition to request detection RequestHandler also provides easy access to altering the output and content type mappings for your application.

setContent($name, $type = null)

  • $name string - The name or file extension of the Content-type ie. html, css, json, xml.

  • $type mixed - The mime-type(s) that the Content-type maps to.

setContent adds/sets the Content-types for the given name. Allows content-types to be mapped to friendly aliases and or extensions. This allows RequestHandler to automatically respond to requests of each type in its startup method. If you are using Router::parseExtension, you should use the file extension as the name of the Content-type. Furthermore, these content types are used by prefers() and accepts().

setContent is best used in the beforeFilter() of your controllers, as this will best leverage the automagicness of content-type aliases.

The default mappings are:

  • javascript text/javascript

  • js text/javascript

  • json application/json

  • css text/css

  • html text/html, */*

  • text text/plain

  • txt text/plain

  • csv application/vnd.ms-excel, text/plain

  • form application/x-www-form-urlencoded

  • file multipart/form-data

  • xhtml application/xhtml+xml, application/xhtml, text/xhtml

  • xhtml-mobile application/vnd.wap.xhtml+xml

  • xml application/xml, text/xml

  • rss application/rss+xml

  • atom application/atom+xml

  • amf application/x-amf

  • wap text/vnd.wap.wml, text/vnd.wap.wmlscript, image/vnd.wap.wbmp

  • wml text/vnd.wap.wml

  • wmlscript text/vnd.wap.wmlscript

  • wbmp image/vnd.wap.wbmp

  • pdf application/pdf

  • zip application/x-zip

  • tar application/x-tar

prefers($type = null)

Determines which content-types the client prefers. If no parameter is given the most likely content type is returned. If $type is an array the first type the client accepts will be returned. Preference is determined primarily by the file extension parsed by Router if one has been provided, and secondly by the list of content-types in HTTP_ACCEPT.

renderAs($controller, $type)

  • $controller - Controller Reference

  • $type - friendly content type name to render content for ex. xml, rss.

Change the render mode of a controller to the specified type. Will also append the appropriate helper to the controller’s helper array if available and not already in the array.

respondAs($type, $options)

  • $type - Friendly content type name ex. xml, rss or a full content type like application/x-shockwave

  • $options - If $type is a friendly type name that has more than one content association, $index is used to select the content type.

Sets the response header based on content-type map names. If DEBUG is greater than 1, the header is not set.

responseType()

Returns the current response type Content-type header or null if one has yet to be set.

mapType($ctype)

Maps a content-type back to an alias