public function index($parent_id = NULL)
 {
     //set the title of the page
     $this->template->title(lang('web_category_list'));
     //find all the categories with paginate and save it in array to past to the view
     $this->template->set("categories", Category::findby($parent_id));
     $this->template->set("category_id", $parent_id);
     $this->template->set('category', Category::find($parent_id));
     //load the view
     $this->template->append_metadata("<script src='js/sortertables.js' type='text/javascript'></script>");
     $this->template->build('categories/list');
 }