How to retrieve GET parameter in Twig template

Question

I'm attempting to retrieve a GET request variable for use in a twig template. For instance if you go to the page myurl.com/node/64?name=Dave I want the page to render

<h1>Dave</h1>

However I'm having trouble retrieving this variable. I've attempted

<h1>{{app.request.get('name')}}</h1>

In my twig template but it turns up empty. How would I retrieve a GET variable from within a twig template?

Answer 1

You didn't say what template this is for, but app is not defined in any of the templates I have seen.

What you could do, is add a theme_preprocess_TEMPLATE function to include the GET params. Here is a page template example:

In your mytheme.theme file, add a hook_preprocess_page function.

/**
 * Implements hook_preprocess_page()
 */
function MYTHEME_preprocess_page(&$vars) {
  $vars['get']['name'] = $_GET['name'];
}

Then in your page.html.twig you can render it like this:

<h1>{{ get.name }}</h1>

Answer 2

You can create a Twig function to achieve this. E.g:

namespace App\Twig;

use Twig\Extension\AbstractExtension;
use Twig\TwigFunction;

class AppExtension extends AbstractExtension
{
    public function getFunctions()
    {
        return [
            new TwigFunction('getQueryArg', [$this, 'getQueryArg']),
        ];
    }

     
    public function getQueryArg(string $argName): string|int {
      return \Drupal::request()->query->get($argName);
    }
}

In TWIG you would call it as: {{ getQueryArg('name') }}

See https://symfony.com/doc/current/templating/twig_extension.html