Hello guys, i'm trying to create multi-level dynamic menu compatible with bootstrap3. I have already done display all records, but without children items. I paste my code, maybe someone know how to fix that.

private static function mapTree($dataset, $parent = 0)
{
	$tree = array();

	foreach ($dataset as $id => $node)
	{
		if ($node->parent_id != $parent) continue;
		$node->children = self::mapTree($dataset, $node->id);
		$tree[$id] = $node;
	}

	return $tree;
}


/**
 * GenerateMenu
 */
private static function prepareMenu($tree)
{
	$data = '<ul class="nav navbar-nav">';

	foreach ($tree as $item)
	{
		$data .= '<li><a href="' . $item->url . '">' . $item->title . '</a></li>';

		if (count($item->children) > 0)
		{
			self::prepareMenu($item->children);
		}
	}

	$data .= '</ul>';

	return $data;
}

/**
 * Create menu
 */
public static function generateMenu()
{
	$urls = parent::all();
	$tree = self::mapTree($urls);
	$data = self::prepareMenu($tree);

	return $data;
}