<li>
         <a href="{{ url('product_list') }}?category_id={{ Category.id }}"><img src="{{ app.config.front_urlpath }}/img/icon_{{ Category.id }}.png" />
              {{ Category.name }}
         </a>
         {% if Category.children|length > 0 %}
             <ul>
             {% for ChildCategory in Category.children %}
                     {{ _self.tree(ChildCategory) }}
             {% endfor %}
             </ul>
         {% endif %}
     </li>