CodeIgniter 4：优化视图层数据处理，避免直接数据库操作

<?php $db = \Config\Database::connect(); ?> // 避免在视图中执行此操作
<?php $submenu = $this->db->query("SELECT * FROM submenu WHERE id_mainmenu = $idmainmenu"); ?> // 避免在视图中执行此操作

// app/Models/MainMenuModel.php
<?php namespace App\Models;

use CodeIgniter\Model;

class MainMenuModel extends Model
{
    protected $table      = 'mainmenu';
    protected $primaryKey = 'id_mainmenu';
    protected $allowedFields = ['menu_name', 'content'];

    // 可以添加获取所有主菜单的方法
    public function getAllMainMenus()
    {
        return $this->findAll();
    }
}

// app/Models/SubMenuModel.php
<?php namespace App\Models;

use CodeIgniter\Model;

class SubMenuModel extends Model
{
    protected $table      = 'submenu';
    protected $primaryKey = 'id_submenu';
    protected $allowedFields = ['id_mainmenu', 'submenu_name'];

    // 可以添加根据主菜单ID获取子菜单的方法，或者获取所有子菜单
    public function getSubMenusByMainMenuId(int $mainMenuId)
    {
        return $this->where('id_mainmenu', $mainMenuId)->findAll();
    }

    public function getAllSubMenus()
    {
        return $this->findAll();
    }
}

// app/Services/MenuService.php
<?php namespace App\Services;

use App\Models\MainMenuModel;
use App\Models\SubMenuModel;

class MenuService
{
    protected $mainMenuModel;
    protected $subMenuModel;

    public function __construct()
    {
        $this->mainMenuModel = new MainMenuModel();
        $this->subMenuModel = new SubMenuModel();
    }

    /**
     * 获取并组织完整的导航菜单数据
     *
     * @return array 结构化的菜单数据
     */
    public function getStructuredMenuData(): array
    {
        $mainMenus = $this->mainMenuModel->getAllMainMenus();
        $subMenus  = $this->subMenuModel->getAllSubMenus(); // 一次性获取所有子菜单

        $structuredMenu = [];
        $subMenusByMainMenu = [];

        // 将子菜单按其所属的主菜单ID进行分组，方便查找
        foreach ($subMenus as $subMenu) {
            $subMenusByMainMenu[$subMenu['id_mainmenu']][] = $subMenu;
        }

        // 将子菜单关联到对应的主菜单
        foreach ($mainMenus as $mainMenu) {
            $mainMenu['sub_menus'] = $subMenusByMainMenu[$mainMenu['id_mainmenu']] ?? [];
            $structuredMenu[] = $mainMenu;
        }

        return $structuredMenu;
    }
}

// app/Controllers/Dashboard.php
<?php namespace App\Controllers;

use App\Controllers\BaseController;
use App\Services\MenuService; // 引入MenuService

class Dashboard extends BaseController
{
    protected $menuService;

    public function __construct()
    {
        $this->menuService = new MenuService();
    }

    public function user()
    {
        $data = [
            'navigationMenu' => $this->menuService->getStructuredMenuData(), // 获取结构化菜单数据
            // 其他可能需要传递给视图的数据
        ];

        return view('dashboard/user', $data);
    }
}

<!-- app/Views/dashboard/user.php -->
<div class="navigation">
  <div class="container">
    <div class="row">
      <div class="navbar">
        <a href="#" class="nav-brand">My Web Admin</a>
        <nav class="nav">
          <ul>
            <?php foreach($navigationMenu as $mainMenuItem): ?>
              <li>
                <a href="#"><?= esc($mainMenuItem['menu_name']); ?></a>
                <?php if (!empty($mainMenuItem['sub_menus'])): ?>
                  <ul>
                    <?php foreach($mainMenuItem['sub_menus'] as $subMenuItem): ?>
                      <li><a href="#"><?= esc($subMenuItem['submenu_name']); ?></a></li>
                    <?php endForeach; ?>
                  </ul>
                <?php endif; ?>
              </li>
            <?php endForeach; ?>
          </ul>
        </nav>
      </div>
    </div>
  </div>
</div>