Controllers

Controllers are the 'C' in MVC. After routing has been applied and the correct controller has been found, your controller's action is called. Your controller should handle interpreting the request data, making sure the correct models are called, and the right response or view is rendered. Controllers can be thought of as middle man between the Model and View. You want to keep your controllers thin, and your models fat. This will help you more easily reuse your code and makes your code easier to test.

Commonly, a controller is used to manage the logic around a single model. For example, if you were building a site for an online bakery, you might have a RecipesController managing your recipes and an IngredientsController managing your ingredients. However, it's also possible to have controllers work with more than one model. In CakePHP, a controller is named after the primary model it handles.

Your application's controllers extend the AppController class, which in turn extends the core Controller class. The AppController class can be defined in /app/Controller/AppController.php and it should contain methods that are shared between all of your application's controllers.

Controllers provide a number of methods that handle requests. These are called actions. By default, each public method in a controller is an action, and is accessible from a URL. An action is responsible for interpreting the request and creating the response. Usually responses are in the form of a rendered view, but there are other ways to create responses as well.

The App Controller

As stated in the introduction, the AppController class is the parent class to all of your application's controllers. AppController itself extends the Controller class included in the CakePHP core library. AppController is defined in /app/Controller/AppController.php as follows:

class AppController extends Controller {
}

Controller attributes and methods created in your AppController will be available to all of your application's controllers. Components (which you'll learn about later) are best used for code that is used in many (but not necessarily all) controllers.

While normal object-oriented inheritance rules apply, CakePHP does a bit of extra work when it comes to special controller attributes. The components and helpers used by a controller are treated specially. In these cases, AppController value arrays are merged with child controller class arrays. The values in the child class will always override those in AppController.

NOTE

CakePHP merges the following variables from the AppController into your application's controllers:

• ~Controller::$components
• ~Controller::$helpers
• ~Controller::$uses

Remember to add the default Html and Form helpers if you define the ~Controller::$helpers property in your AppController.

Also remember to call AppController's callbacks within child controller callbacks for best results:

public function beforeFilter() {
    parent::beforeFilter();
}

Request parameters

When a request is made to a CakePHP application, CakePHP's Router and Dispatcher classes use Routes Configuration to find and create the correct controller. The request data is encapsulated in a request object. CakePHP puts all of the important request information into the $this->request property. See the section on Cake Request for more information on the CakePHP request object.

Controller actions

Controller actions are responsible for converting the request parameters into a response for the browser/user making the request. CakePHP uses conventions to automate this process and remove some boilerplate code you would otherwise need to write.

By convention, CakePHP renders a view with an inflected version of the action name. Returning to our online bakery example, our RecipesController might contain the view(), share(), and search() actions. The controller would be found in /app/Controller/RecipesController.php and contain:

# /app/Controller/RecipesController.php

class RecipesController extends AppController {
    public function view($id) {
        //action logic goes here..
    }

    public function share($customerId, $recipeId) {
        //action logic goes here..
    }

    public function search($query) {
        //action logic goes here..
    }
}

The view files for these actions would be app/View/Recipes/view.ctp, app/View/Recipes/share.ctp, and app/View/Recipes/search.ctp. The conventional view file name is the lowercased and underscored version of the action name.

Controller actions generally use ~Controller::set() to create a context that View uses to render the view. Because of the conventions that CakePHP uses, you don't need to create and render the view manually. Instead, once a controller action has completed, CakePHP will handle rendering and delivering the View.

If for some reason you'd like to skip the default behavior, both of the following techniques will bypass the default view rendering behavior.

• If you return a string, or an object that can be converted to a string from your controller action, it will be used as the response body.
• You can return a CakeResponse object with the completely created response.

When you use controller methods with ~Controller::requestAction(), you will often want to return data that isn't a string. If you have controller methods that are used for normal web requests + requestAction, you should check the request type before returning:

class RecipesController extends AppController {
    public function popular() {
        $popular = $this->Recipe->popular();
        if (!empty($this->request->params['requested'])) {
            return $popular;
        }
        $this->set('popular', $popular);
    }
}

The above controller action is an example of how a method can be used with ~Controller::requestAction() and normal requests. Returning array data to a non-requestAction request will cause errors and should be avoided. See the section on ~Controller::requestAction() for more tips on using ~Controller::requestAction()

In order for you to use a controller effectively in your own application, we'll cover some of the core attributes and methods provided by CakePHP's controllers.

Request Life-cycle callbacks

class Controller

CakePHP controllers come fitted with callbacks you can use to insert logic around the request life-cycle:

method Controller::beforeFilter()

method Controller::beforeRender()

method Controller::afterFilter()

In addition to controller life-cycle callbacks, Components also provide a similar set of callbacks.

Controller Methods

For a complete list of controller methods and their descriptions visit the CakePHP API.

Interacting with Views

Controllers interact with views in a number of ways. First, they are able to pass data to the views, using ~Controller::set(). You can also decide which view class to use, and which view file should be rendered from the controller.

method Controller::set(string $var, mixed $value)

method Controller::render(string $view, string $layout)

Rendering a specific view

In your controller, you may want to render a different view than the conventional one. You can do this by calling ~Controller::render() directly. Once you have called ~Controller::render(), CakePHP will not try to re-render the view:

class PostsController extends AppController {
    public function my_action() {
        $this->render('custom_file');
    }
}

This would render app/View/Posts/custom_file.ctp instead of app/View/Posts/my_action.ctp

You can also render views inside plugins using the following syntax: $this->render('PluginName.PluginController/custom_file'). For example:

class PostsController extends AppController {
    public function my_action() {
        $this->render('Users.UserDetails/custom_file');
    }
}

This would render app/Plugin/Users/View/UserDetails/custom_file.ctp

Flow Control

method Controller::redirect(mixed $url, integer $status, boolean $exit)

method Controller::flash(string $message, string|array $url, integer $pause, string $layout)

Callbacks

In addition to the Controller Life Cycle, CakePHP also supports callbacks related to scaffolding.

method Controller::beforeScaffold($method)

method Controller::afterScaffoldSave($method)

method Controller::afterScaffoldSaveError($method)

method Controller::scaffoldError($method)

Other Useful Methods

method Controller::constructClasses()

method Controller::referer(mixed $default = null, boolean $local = false)

method Controller::disableCache()

method Controller::postConditions(array $data, mixed $op, string $bool, boolean $exclusive)

method Controller::paginate()

method Controller::requestAction(string $url, array $options)

method Controller::loadModel(string $modelClass, mixed $id)

Controller Attributes

For a complete list of controller attributes and their descriptions visit the CakePHP API.

The ~Controller::$name attribute should be set to the name of the controller. Usually this is just the plural form of the primary model the controller uses. This property can be omitted, but saves CakePHP from inflecting it:

// $name controller attribute usage example
class RecipesController extends AppController {
   public $name = 'Recipes';
}

$components, $helpers and $uses

The next most often used controller attributes tell CakePHP what ~Controller::$helpers, ~Controller::$components, and models you'll be using in conjunction with the current controller. Using these attributes make MVC classes given by ~Controller::$components and ~Controller::$uses available to the controller as class variables ($this->ModelName, for example) and those given by ~Controller::$helpers to the view as an object reference variable ($this->{$helpername}).

NOTE

Each controller has some of these classes available by default, so you may not need to configure your controller at all.

Controllers have access to their primary model available by default. Our RecipesController will have the Recipe model class available at $this->Recipe, and our ProductsController also features the Product model at $this->Product. However, when allowing a controller to access additional models through the ~Controller::$uses variable, the name of the current controller's model must also be included. This is illustrated in the example below.

If you do not wish to use a Model in your controller, set public $uses = array(). This will allow you to use a controller without a need for a corresponding Model file. However, the models defined in the AppController will still be loaded. You can also use false to not load any models at all. Even those defined in the AppController.

Changed in version 2.1

~Controller::$uses now has a new default value, it also handles false differently.

The HtmlHelper, FormHelper, and SessionHelper are available by default, as is the SessionComponent. But if you choose to define your own ~Controller::$helpers array in AppController, make sure to include HtmlHelper and FormHelper if you want them still available by default in your Controllers. To learn more about these classes, be sure to check out their respective sections later in this manual.

Let's look at how to tell a CakePHP Controller that you plan to use additional MVC classes:

class RecipesController extends AppController {
    public $uses = array('Recipe', 'User');
    public $helpers = array('Js');
    public $components = array('RequestHandler');
}

Each of these variables are merged with their inherited values, therefore it is not necessary (for example) to redeclare the FormHelper, or anything that is declared in your AppController.

The components array allows you to set which Components a controller will use. Like ~Controller::$helpers and ~Controller::$uses components in your controllers are merged with those in AppController. As with ~Controller::$helpers you can pass settings into ~Controller::$components. See Configuring Components for more information.

Other Attributes

While you can check out the details for all controller attributes in the API, there are other controller attributes that merit their own sections in the manual.

The cacheAction attribute is used to define the duration and other information about full page caching. You can read more about full page caching in the CacheHelper documentation.

The paginate attribute is a deprecated compatibility property. Using it loads and configures the PaginatorComponent. It is recommended that you update your code to use normal component settings:

class ArticlesController extends AppController {
    public $components = array(
        'Paginator' => array(
            'Article' => array(
                'conditions' => array('published' => 1)
            )
        )
    );
}

This chapter should be less about the controller API and more about examples, the controller attributes section is overwhelming and difficult to understand at first. The chapter should start with some example controllers and what they do.

More on controllers

• Request and Response objects
• Scaffolding
• The Pages Controller
• Components