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Components

Components are packages of logic that are shared between controllers. CakePHP comes with a fantastic set of core components you can use to aid in various common tasks. You can also create your own components. If you find yourself wanting to copy and paste things between controllers, you should consider creating your own component to contain the functionality. Creating components keeps controller code clean and allows you to reuse code between different controllers.

For more information on the components included in CakePHP, check out the chapter for each component:

Configuring Components

Many of the core components require configuration. Some examples of components requiring configuration are AuthComponent and Cookie. Configuration for these components, and for components in general, is usually done via loadComponent() in your Controller’s initialize() method or via the $components array:

class PostsController extends AppController
{
    public function initialize()
    {
        parent::initialize();
        $this->loadComponent('Auth', [
            'authorize' => 'Controller',
            'loginAction' => ['controller' => 'Users', 'action' => 'login']
        ]);
        $this->loadComponent('Cookie', ['expires' => '1 day']);
    }

}

You can configure components at runtime using the config() method. Often, this is done in your controller’s beforeFilter() method. The above could also be expressed as:

public function beforeFilter(Event $event)
{
    $this->Auth->config('authorize', ['controller']);
    $this->Auth->config('loginAction', ['controller' => 'Users', 'action' => 'login']);

    $this->Cookie->config('name', 'CookieMonster');
}

Like helpers, components implement a config() method that is used to get and set any configuration data for a component:

// Read config data.
$this->Auth->config('loginAction');

// Set config
$this->Csrf->config('cookieName', 'token');

As with helpers, components will automatically merge their $_defaultConfig property with constructor configuration to create the $_config property which is accessible with config().

Aliasing Components

One common setting to use is the className option, which allows you to alias components. This feature is useful when you want to replace $this->Auth or another common Component reference with a custom implementation:

// src/Controller/PostsController.php
class PostsController extends AppController
{
    public function initialize()
    {
        $this->loadComponent('Auth', [
            'className' => 'MyAuth'
        ]);
    }
}

// src/Controller/Component/MyAuthComponent.php
use Cake\Controller\Component\AuthComponent;

class MyAuthComponent extends AuthComponent
{
    // Add your code to override the core AuthComponent
}

The above would alias MyAuthComponent to $this->Auth in your controllers.

Note

Aliasing a component replaces that instance anywhere that component is used, including inside other Components.

Loading Components on the Fly

You might not need all of your components available on every controller action. In situations like this you can load a component at runtime using the loadComponent() method in your controller:

// In a controller action
$this->loadComponent('OneTimer');
$time = $this->OneTimer->getTime();

Note

Keep in mind that components loaded on the fly will not have missed callbacks called. If you rely on the beforeFilter or startup callbacks being called, you may need to call them manually depending on when you load your component.

Using Components

Once you’ve included some components in your controller, using them is pretty simple. Each component you use is exposed as a property on your controller. If you had loaded up the Cake\Controller\Component\FlashComponent in your controller, you could access it like so:

class PostsController extends AppController
{
    public function initialize()
    {
        parent::initialize();
        $this->loadComponent('Flash');
    }

    public function delete()
    {
        if ($this->Post->delete($this->request->getData('Post.id')) {
            $this->Flash->success('Post deleted.');
            return $this->redirect(['action' => 'index']);
        }
    }

Note

Since both Models and Components are added to Controllers as properties they share the same ‘namespace’. Be sure to not give a component and a model the same name.

Creating a Component

Suppose our application needs to perform a complex mathematical operation in many different parts of the application. We could create a component to house this shared logic for use in many different controllers.

The first step is to create a new component file and class. Create the file in src/Controller/Component/MathComponent.php. The basic structure for the component would look something like this:

namespace App\Controller\Component;

use Cake\Controller\Component;

class MathComponent extends Component
{
    public function doComplexOperation($amount1, $amount2)
    {
        return $amount1 + $amount2;
    }
}

Note

All components must extend Cake\Controller\Component. Failing to do this will trigger an exception.

Including your Component in your Controllers

Once our component is finished, we can use it in the application’s controllers by loading it during the controller’s initialize() method. Once loaded, the controller will be given a new attribute named after the component, through which we can access an instance of it:

// In a controller
// Make the new component available at $this->Math,
// as well as the standard $this->Csrf
public function initialize()
{
    parent::initialize();
    $this->loadComponent('Math');
    $this->loadComponent('Csrf');
}

When including Components in a Controller you can also declare a set of parameters that will be passed on to the Component’s constructor. These parameters can then be handled by the Component:

// In your controller.
public function initialize()
{
    parent::initialize();
    $this->loadComponent('Math', [
        'precision' => 2,
        'randomGenerator' => 'srand'
    ]);
    $this->loadComponent('Csrf');
}

The above would pass the array containing precision and randomGenerator to MathComponent::initialize() in the $config parameter.

Using Other Components in your Component

Sometimes one of your components may need to use another component. In this case you can include other components in your component the exact same way you include them in controllers - using the $components var:

// src/Controller/Component/CustomComponent.php
namespace App\Controller\Component;

use Cake\Controller\Component;

class CustomComponent extends Component
{
    // The other component your component uses
    public $components = ['Existing'];

    // Execute any other additional setup for your component.
    public function initialize(array $config)
    {
        $this->Existing->foo();
    }

    public function bar()
    {
        // ...
    }
}

// src/Controller/Component/ExistingComponent.php
namespace App\Controller\Component;

use Cake\Controller\Component;

class ExistingComponent extends Component
{
    public function foo()
    {
        // ...
    }
}

Note

In contrast to a component included in a controller no callbacks will be triggered on a component’s component.

Accessing a Component’s Controller

From within a Component you can access the current controller through the registry:

$controller = $this->_registry->getController();

You can access the controller in any callback method from the event object:

$controller = $event->getSubject();

Component Callbacks

Components also offer a few request life-cycle callbacks that allow them to augment the request cycle.

beforeFilter(Event $event)

Is called before the controller’s beforeFilter method, but after the controller’s initialize() method.

startup(Event $event)

Is called after the controller’s beforeFilter method but before the controller executes the current action handler.

beforeRender(Event $event)

Is called after the controller executes the requested action’s logic, but before the controller renders views and layout.

shutdown(Event $event)

Is called before output is sent to the browser.

beforeRedirect(Event $event, $url, Response $response)

Is invoked when the controller’s redirect method is called but before any further action. If this method returns false the controller will not continue on to redirect the request. The $url, and $response parameters allow you to inspect and modify the location or any other headers in the response.