chaoyu/app/widget/Menu.php

<?php
namespace app\widget;

use think\facade\{View, Cache};
use app\model\Category;

class Menu
{
    public function index($categoryId)
    {
        $menus = Cache::get('front_menus');
        $menus = null;
        if(empty($menus)){
            $menus = Category::getListForFrontMenu();
            Cache::set('front_menus', $menus, 3600 * 12);
        }
        $currentFirstId = 0;
        if (is_numeric($categoryId) && $categoryId > 0) {
            $currentFirstId = Category::firstGradeById($categoryId);
        }
        $data = [
            'categoryId' => $categoryId,
            'menus' => $menus,
            'currentFirstId' => $currentFirstId,
        ];
        return View::assign($data)->fetch('public/menu');
    }
}