How to var_dump variables in twig templates?

Question

View layer pattern where you only present what you have been given is fine and all, but how do you know what is available? Is there a \"list all defined variables\" function

Answer 1

If you are in an environment where you can't use the dump function (ex: opencart), you can try:

{{ my_variable | json_encode(constant('JSON_PRETTY_PRINT')) }}

Answer 2

Since Symfony >= 2.6, there is a nice VarDumper component, but it is not used by Twig's dump() function.

To overwrite it, we can create an extension:

In the following implementation, do not forget to replace namespaces.

Fuz/AppBundle/Resources/config/services.yml

parameters:
   # ...
   app.twig.debug_extension.class: Fuz\AppBundle\Twig\Extension\DebugExtension

services:
   # ...
   app.twig.debug_extension:
       class: %app.twig.debug_extension.class%
       arguments: []
       tags:
           - { name: twig.extension }

Fuz/AppBundle/Twig/Extension/DebugExtension.php

<?php

namespace Fuz\AppBundle\Twig\Extension;

class DebugExtension extends \Twig_Extension
{

    public function getFunctions()
    {
        return array (
              new \Twig_SimpleFunction('dump', array('Symfony\Component\VarDumper\VarDumper', 'dump')),
        );
    }

    public function getName()
    {
        return 'FuzAppBundle:Debug';
    }

}