How to retrieve all Variables from a Twig Template?

Question

Is it possible to retrieve all variables inside a Twig template with PHP?

Example someTemplate.twig.php:

Hello {{ name }}, 
your new email is {{ ema         


        

Answer 1

Here is the best way and easiest way to dump all variables :

{{ dump () }}

Source : https://www.drupal.org/docs/8/theming/twig/discovering-and-inspecting-variables-in-twig-templates

Answer 2

You have to parse the template, and walk through the AST it returns:

$loaded = $twig->getLoader()->getSource($template);
var_dump(extractVars($twig->parse($twig->tokenize($loaded))));

function extractVars($node)
{
    if (!$node instanceof Traversable) return array();

    $vars = array();
    foreach ($node as $cur)
    {
        if (get_class($cur) != 'Twig_Node_Expression_Name')
        {
            $vars = array_merge($vars, call_user_func(__FUNCTION__, $cur));
        }
        else if ($cur->getAttribute('always_defined') == false)
        {
            // List only predefined variables expected by template, 
            // filtering out `v` and leaving `arr` from `{% for v in arr%}`
            $vars[] = $cur->getAttribute('name');
        }
    }

    return $vars;
}