Request Handling

class RequestHandlerComponent(ComponentCollection $collection, array $config = [])

The Request Handler component is used in CakePHP to obtain additional information about the HTTP requests that are made to your application. You can use it to see what content types clients prefer, automatically parse request input, define how content types map to view classes or template paths.

By default RequestHandler will automatically detect AJAX requests based on the X-Requested-With HTTP header that many JavaScript libraries use. When used in conjunction with Cake\Routing\Router::extensions(), RequestHandler will automatically switch the layout and template files to those that match non-HTML media types. 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/JSON data is POST’ed to your Controllers, it will be parsed into an array which is assigned to $this->request->getData(), and can then be accessed as you would standard POST data. In order to make use of RequestHandler it must be included in your initialize() method:

class WidgetsController extends AppController
    public function initialize()

    // Rest of controller

Obtaining Request Information

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

RequestHandlerComponent::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 ArticlesController extends AppController
    public function initialize()

    public function beforeFilter(Event $event)
        if ($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(['xml', 'rss', 'atom'])) {
            // Executes if the client accepts any of the above: XML, RSS
            // or Atom.

Other request ‘type’ detection methods include:


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


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


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


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:

  • Android

  • AvantGo

  • BlackBerry

  • DoCoMo

  • Fennec

  • iPad

  • iPhone

  • iPod

  • J2ME

  • MIDP

  • NetFront

  • Nokia

  • Opera Mini

  • Opera Mobi

  • PalmOS

  • PalmSource

  • portalmmm

  • Plucker

  • ReqwirelessWeb

  • SonyEricsson

  • Symbian

  • UP.Browser

  • webOS

  • Windows CE

  • Windows Phone OS

  • Xiino


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->request->is('ajax')) {
    $this->response = $this->response->withDisabledCache();

    // Prior to 3.4.0
// Continue Controller action

Automatically Decoding Request Data

Add a request data decoder. The handler should contain a callback, and any additional arguments for the callback. The callback should return an array of data contained in the request input. For example adding a CSV handler could look like:

class ArticlesController extends AppController
    public function initialize()
        $parser = function ($data) {
            $rows = str_getcsv($data, "\n");
            foreach ($rows as &$row) {
                $row = str_getcsv($row, ',');
            return $rows;
        $this->loadComponent('RequestHandler', [
            'inputTypeMap' => [
                'csv' => [$parser]

You can use any callable for the handling function. You can also pass additional arguments to the callback, this is useful for callbacks like json_decode:

$this->RequestHandler->addInputType('json', ['json_decode', true]);

// After 3.1.0 you should use
$this->RequestHandler->config('inputTypeMap.json', ['json_decode', true]);

The above will make $this->request->getData() an array of the JSON input data, without the additional true you’d get a set of stdClass objects.

Deprecated since version 3.1.0: As of 3.1.0 the addInputType() method is deprecated. You should use config() to add input types at runtime.

Changed in version 3.6.0: You should prefer using Body Parser Middleware instead of RequestHandlerComponent.

Checking Content-Type Preferences

RequestHandlerComponent::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:


Responding To Requests

RequestHandlerComponent::renderAs($controller, $type)

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:

// Force the controller to render an xml response.
$this->RequestHandler->renderAs($this, 'xml');

This method will also attempt to add a helper that matches your current content type. For example if you render as rss, the RssHelper will be added.

RequestHandlerComponent::respondAs($type, $options)

Sets the response header based on content-type map names. This method lets you set a number of response properties at once:

$this->RequestHandler->respondAs('xml', [
    // Force download
    'attachment' => true,
    'charset' => 'UTF-8'

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

Taking Advantage of HTTP Cache Validation

The HTTP cache validation model is one of the processes used for cache gateways, also known as reverse proxies, to determine if they can serve a stored copy of a response to the client. Under this model, you mostly save bandwidth, but when used correctly you can also save some CPU processing, reducing this way response times.

Enabling the RequestHandlerComponent in your controller automatically activates a check done before rendering the view. This check compares the response object against the original request to determine whether the response was not modified since the last time the client asked for it.

If response is evaluated as not modified, then the view rendering process is stopped, saving processing time, saving bandwidth and no content is returned to the client. The response status code is then set to 304 Not Modified.

You can opt-out this automatic checking by setting the checkHttpCache setting to false:

public function initialize()
    $this->loadComponent('RequestHandler', [
        'checkHttpCache' => false

Using Custom ViewClasses

When using JsonView/XmlView you might want to override the default serialization with a custom View class, or add View classes for other types.

You can map existing and new types to your custom classes. You can also set this automatically by using the viewClassMap setting:

public function initialize()
    $this->loadComponent('RequestHandler', [
        'viewClassMap' => [
            'json' => 'ApiKit.MyJson',
            'xml' => 'ApiKit.MyXml',
            'csv' => 'ApiKit.Csv'

Deprecated since version 3.1.0: As of 3.1.0 the viewClassMap() method is deprecated. You should use config() to change the viewClassMap at runtime.