MVC架构中控制器与数据访问层的合理交互

// 1. 定义数据仓库接口
interface UserRepository
{
    public function findById(int $id): ?User;
    public function save(User $user): void;
    public function delete(User $user): void;
}

// 2. 实现数据仓库（例如，使用ORM或PDO）
class EloquentUserRepository implements UserRepository
{
    public function findById(int $id): ?User
    {
        // 实际的数据库查询逻辑，例如：
        return User::find($id);
    }

    public function save(User $user): void
    {
        $user->save();
    }

    public function delete(User $user): void
    {
        $user->delete();
    }
}

// 3. 定义服务层接口
interface UserService
{
    public function getUserProfile(int $userId): ?UserProfileData;
    public function updateUserName(int $userId, string $newName): bool;
}

// 4. 实现服务层（包含业务逻辑）
class UserApplicationService implements UserService
{
    private UserRepository $userRepository;

    public function __construct(UserRepository $userRepository)
    {
        $this->userRepository = $userRepository;
    }

    public function getUserProfile(int $userId): ?UserProfileData
    {
        $user = $this->userRepository->findById($userId);
        if (!$user) {
            return null;
        }
        // 假设 UserProfileData 是一个DTO或简单的对象
        return new UserProfileData($user->id, $user->name, $user->email);
    }

    public function updateUserName(int $userId, string $newName): bool
    {
        $user = $this->userRepository->findById($userId);
        if (!$user) {
            return false;
        }
        // 业务逻辑：例如，检查新名称是否有效
        if (strlen($newName) < 3) {
            return false; // 名称太短
        }
        $user->name = $newName;
        $this->userRepository->save($user);
        return true;
    }
}

// 5. 控制器层（处理请求，委托给服务层）
class UserController
{
    private UserService $userService;

    public function __construct(UserService $userService)
    {
        $this->userService = $userService;
    }

    public function showProfile(int $userId)
    {
        $profile = $this->userService->getUserProfile($userId);

        if (!$profile) {
            // 返回404或错误信息
            return response()->json(['message' => 'User not found'], 404);
        }

        // 渲染视图或返回JSON
        return response()->json($profile);
    }

    public function updateName(int $userId, string $newName)
    {
        if ($this->userService->updateUserName($userId, $newName)) {
            return response()->json(['message' => 'Name updated successfully']);
        } else {
            return response()->json(['message' => 'Failed to update name'], 400);
        }
    }
}