public function uniqueSlug($slug_str, $tag_name)
	{
		$model = $this->tagModelString();
		if (!empty($slug_str) && $tag = $model::where('slug', $slug_str)->first()) {
			// 只有当 slug 一样但 tagname 不一样的情况下，才自动设置随机 slug 后缀
			if ($tag->name != $this->normalizeTagName($tag_name)) {
				$slug_str .= '-'. mt_rand(1000, 9999);
			}
		}
		return $slug_str;
	}