public function getRole($force = false)
     {
         if ($this->nb_role === null || $force) {
             $this->nb_role = null;
             if ($this->isValueNumeric('nb_role_id')) {
                 $nb_role = new CNabuRole($this);
                 if ($nb_role->isFetched()) {
                     $this->nb_role = $nb_role;
                 }
             }
         }

         return $this->nb_role;
     }