Access Controller variable from Component - CakePHP

You can get the Controller of Component in CakePhp 3.x as below:

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

If you had a variable in your Controller called $fooVariable, you would access it in an associated component as follows: $this->getController()->myVariable.

Note that the variable need to be public in the controller. If the variable is protected or private, you may inject it in the component while loading it.

Components are accessed the same was as Models in Cake from a controller. I've created a Test component and included it in both a controller from the main application, and a controller from a plugin:

app/controllers/components/test.php

class TestComponent extends Object {
    public $allowedExtensions = array(); // put your defaults in the component
}

app/controllers/my_controller.php

class MyController extends AppController {
    // ... vars
    var $components = array('Test', /* ...others */);
    var $layout = '';

    public function test() {
        $this->render(false);

        // get current values from component
        debug($this->Test->allowedExtensions);

        // add a JPG
        $this->Test->allowedExtensions[] = 'jpg';
        debug($this->Test->allowedExtensions);

        // add a MP3
        $this->Test->allowedExtensions[] = 'mp3';
        debug($this->Test->allowedExtensions);
    }
}

Output from this test is:

app\controllers\my_controller.php (line n) Array ( )

app\controllers\my_controller.php (line n) Array ( [0] => jpg )

app\controllers\my_controller.php (line n) Array ( [0] => jpg [1] => mp3 )

So from this you can see that the public property of the Test component is available from any controller that uses it.

Using the exact same method to include the component from the main project (plugin specific models, components etc need to be prefixed with the plugin's name) produces the same results, you can in fact control that component property from a plugin or any controller individually and still have your default values in the component it self.