How works the pseudo-variable $this in symfony?

Question

I understand the official explanation about the $this: http://php.net/manual/en/language.oop5.basic.php

But if I try to understand what is the object reference in this case of symfony, I don't know who is it, for example:

Each time when you need to return the theme, use this:

public function indexAction()
    {
        return $this->render('foo/bar.html.twig', array());
    }

Or when you generate a some form:

public function indexAction(Request $request)
    {

        // Create the form

        $form = $this->createFormBuilder()
                ->add('name', TextType::class)
                ->add('email', EmailType::class)
                ->add('subject', TextType::class)
                ->add('message', TextareaType::class)
                ->add('send', SubmitType::class)
                ->getForm();
}

But who is exactly the object $this? and if working with other word or value that is not $this, only for try to understand better.

There is nothing magic about it, it's still a instance of your class. — tkausl, Feb 05 '16 at 19:39
Take a look at the Symfony base controller class: https://github.com/symfony/symfony/blob/master/src/Symfony/Bundle/FrameworkBundle/Controller/Controller.php That is where the methods render and createFormBuilder are defined. Might make it a bit easier to understand what is happening. — Cerad, Feb 05 '16 at 19:43

score 1 · Accepted Answer · answered Feb 05 '16 at 20:22

If you are asking where are located the methods called by $this in your controller, take a look at the extends statement of your controller (just after class declaration).

All your controllers extends (by default) the FrameworkBundle Controller, also you can access all of the inherited methods, such as createForm, render, getDoctrine, generateUrl.

The parent Controller extends from ContainerAware (Dependency Injection), it allows you to access and use services.
Most of the methods I listed are just shortcuts of services methods.

i.e. $this->generateUrl(/*params*/) is equal to $this->container->get('router')->generate(/*params/*)

score 0 · Answer 2 · edited May 23 '17 at 11:46

In that case $this references an instance of the object eg. you are in a controller, then the $this variable references the current instance of the controller that you are in, and you can access all the methods that the class itself has and all the methods of the extended class in this case the base controller and so on in the inheritance hierarchy.

You can read this question to get more clarity.

How does the "this" keyword work?

score 0 · Answer 3 · answered Feb 05 '16 at 19:49

$this is how instances of a class in refer to themselves in PHP.

class Person
  private $name;

  public function __construct($name){
    $this->name = $name;
  }

  public function getName($name){
    $this->name = $name;
  }
end

When you create a instance of the class with $foo = new Person('Max');. $this referrers to the new instance you are creating. When you use $this in a controller - this refers to the controller itself.

In natural language its like saying my.

How works the pseudo-variable $this in symfony?

3 Answers3