Get error while trying to load a twig filter I'm working on

After read the docs I tried my first filter but got this error

The filter "sanitize_for_image_url" does not exist in /var/www/html/src/CategoryBundle/Resources/views/Default/menu.html.twig at line 5.

What I did was:

• Create a folder under my bundle directory and call it Twig.

• Under that folder create the file CategoryExtension.php and add this code:

  <?php
  
  namespace CategoryBundle\Twig;
  
  class CategoryExtension extends \Twig_Extension {
  
  public function getFilters() {
      return array(
          new \Twig_SimpleFilter('price', array($this, 'priceFilter')),
      );
  }
  
  public function sanitize_for_image_urlFilter($image) {
      $image = strtolower($image);
      $image = preg_replace('/[^a-z0-9 -]+/', '', $image);
      $image = str_replace(' ', '-', $image);
  
      return $image;
  }
  
  public function getName() {
      return 'category_extension';
  }
  

  }

• Create a folder inside \CategoryBundle\Resources and called "config" and under config created the file "services.yml" with this content:

  services:
      category.twig.category_extension:
          class: CategoryBundle\Twig\CategoryExtension
          tags:
              - { name: twig.extension }
  

• Call the filter in my twig template as follow:

  <img src="{{ asset('bundles/dashboard/img/categories/' ~ entity.getName|lower|sanitize_for_image_url ~ '.gif') }}">
  

Did I miss something else?

You're not telling twig about your new filter. You'll also need to modify the getFilters() method of your class.