如何获得类别模块opencart 2.0.3中的第3级类别

Question

我想在左侧边栏的类别页面上获得第3级别类别，但我无法获得子ID，这是我获得第3级别类别的代码：

$children_lv3_data = array();

if ($child['category_id'] == $data['child_id']) {
    $children_lv3 = $this->model_catalog_category->getCategories($child['category_id']);

    foreach ($children_lv3 as $child_lv3) {
        $filter_data_lv3 = array(
            'filter_category_id'  => $child_lv3['category_id'],
            'filter_sub_category' => true
        );

        $children_lv3_data[] = array(
            'category_id' => $child_lv3['category_id'],
            'name'  => $child_lv3['name'] . ($this->config->get('config_product_count') ? ' (' . $this->model_catalog_product->getTotalProducts($filter_data_lv3) . ')' : ''),
            'href'  => $this->url->link('product/category', 'path=' . $category['category_id'] . '_' . $child['category_id'] . '_' . $child_lv3['category_id'])
        );
    }
}