What I didn’t knew about controllers without models

Up to now I thought the two ways to create a controller without a model are equivalent:

class MyController extends AppController {
    var $uses = null;
}

versus

class MyController extends AppController {
    var $uses = array();
}

And so whenever I had to create such a controller, I simply used one of those approaches without much thought.

Recently, I had a controller using the first approach with null. Everything worked fine. Then a model got added to the AppController’s $uses array to do some stuff with that model in the beforeRender() method. This worked fine with the controllers using models, but it caused an “undefined property” error when I called the controller without model.

The reason for this “problem” is, that var $uses = null; overrides the value from the parent class and so the model is no longer defined in the AppController, hence the error. This behavior is correct from an object-oriented point of view, but it is unexpected in CakePHP (at least for me). Because if it would work in the object-oriented way, there would be errors in the other controllers, too. But due to Cake’s magic, a $uses array defined in a controller doesn’t override the $uses array of the AppController, instead those arrays get merged. And so I expected that something like that would happen when using null as value for the $uses variable ;-)

So the solution to fix the “undefined property” error was to use var $uses = array();