public function getCatalog($force = false)
    {
        if ($this->nb_catalog === null || $force) {
            $this->nb_catalog = null;
            if ($this instanceof CNabuDataObject &&
                !$this->isBuiltIn()
                && $this->isValueNumeric(NABU_CATALOG_FIELD_ID)
            ) {
                $nb_aux_catalog = new CNabuCatalog($this->getValue(NABU_CATALOG_FIELD_ID));
                if ($nb_aux_catalog->isFetched()) {
                    $this->nb_catalog = $nb_aux_catalog;
                }
            }
        }

        return $this->nb_catalog;
    }