dcat树分类经过处理后，  没转换成空格

public function getCategories(): JsonResponse
    {
        $nav_id = request()->input('q');
        $categories = Category::selectOptions(function ($q) use ($nav_id) {
            return $q->where('nav_id', $nav_id);
        });
        unset($categories[0]);

        $arr = [];
        foreach ($categories as $k=>$category) {
            $arr[$k]['id'] = $k;
            $arr[$k]['text'] = $category;
        }

        return response()->json($arr);
    }