public function listCategorySub($parent, $space = '|---') { global $arr; $children = Categories::find()->where(['parent_id' => $parent])->all(); foreach ($children as $child) { $data = array(); $data['id'] = $child->id; $data['title'] = $space . ' ' . $child->title; $arr[] = $data; Categories::listCategorySub($child->id, $space . '---'); } }