public function __tocsv($structureId = null){

        // Create pager for material collection
        $pager = new Pager(0);

        // Get collection
        $collection = new $this->collectionClass($this, new dbQuery(), $pager);

        // Set navigation
        if (isset(static::$navigation)) {
            $collection = $collection->navigation(static::$navigation);
        } else {
            $collection = $collection->navigation(array($structureId));
        }
        $collection->fill();

        $this->tocsv($collection);
    }