public function computeSlug()
    {
        if ($this->is_page) {
            return $this->alias;
        }

        if (! $this->exists) {
            $category = Category::query()->findOrFail($this->category_id);
        } else {
            $category = $this->category;
        }

        return $category->slug . '/' . $this->alias;
    }