MVC架构中控制器、服务层与仓储层的职责边界：为什么控制器不应直接调用仓储层？

<?php

namespace App\Http\Controllers;

use App\Repositories\UserRepository;
use Illuminate\Http\Request;
use App\Models\User; // 假设User是领域模型

class BadUserController extends Controller
{
    private UserRepository $userRepository;

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

    /**
     * 创建一个新用户
     */
    public function createUser(Request $request)
    {
        // 1. 输入验证 (通常由FormRequest处理，此处简化)
        $validatedData = $request->validate([
            'name' => 'required|string|max:255',
            'email' => 'required|string|email|max:255|unique:users',
            'password' => 'required|string|min:8',
        ]);

        // 2. 业务逻辑（直接在控制器中处理，如密码加密、默认值设置）
        $validatedData['password'] = bcrypt($validatedData['password']);
        if (!isset($validatedData['status'])) {
            $validatedData['status'] = 'active'; // 默认状态
        }

        // 3. 数据持久化（直接调用仓储）
        $user = $this->userRepository->create($validatedData);

        // 4. 更多业务逻辑（如发送欢迎邮件，可能也在此处触发）
        // EmailService::sendWelcomeEmail($user->email);

        return response()->json($user, 201);
    }
}

<?php

namespace App\Repositories;

use App\Models\User;

interface UserRepository
{
    public function findById(int $id): ?User;
    public function findByEmail(string $email): ?User;
    public function create(array $data): User;
    public function update(int $id, array $data): User;
    public function delete(int $id): bool;
}

class EloquentUserRepository implements UserRepository
{
    public function findById(int $id): ?User
    {
        return User::find($id);
    }

    public function findByEmail(string $email): ?User
    {
        return User::where('email', $email)->first();
    }

    public function create(array $data): User
    {
        return User::create($data);
    }

    public function update(int $id, array $data): User
    {
        $user = User::findOrFail($id);
        $user->update($data);
        return $user;
    }

    public function delete(int $id): bool
    {
        return User::destroy($id);
    }
}

<?php

namespace App\Services;

use App\Repositories\UserRepository;
use App\Models\User;
// use App\Services\EmailService; // 假设有邮件服务

class UserService
{
    private UserRepository $userRepository;
    // private EmailService $emailService; // 如果需要发送邮件，注入邮件服务

    public function __construct(UserRepository $userRepository /*, EmailService $emailService */)
    {
        $this->userRepository = $userRepository;
        // $this->emailService = $emailService;
    }

    /**
     * 注册一个新用户，包含所有业务逻辑
     */
    public function registerUser(array $userData): User
    {
        // 1. 业务逻辑：确保邮箱唯一性（如果仓储层没有强制约束）
        if ($this->userRepository->findByEmail($userData['email'])) {
            throw new \InvalidArgumentException('Email already exists.');
        }

        // 2. 业务逻辑：密码加密
        $userData['password'] = bcrypt($userData['password']);

        // 3. 业务逻辑：设置默认值
        if (!isset($userData['status'])) {
            $userData['status'] = 'active';
        }

        // 4. 数据持久化（通过仓储层）
        $user = $this->userRepository->create($userData);

        // 5. 更多业务逻辑：发送欢迎邮件
        // $this->emailService->sendWelcomeEmail($user->email);

        return $user;
    }

    /**
     * 更新用户资料的业务逻辑
     */
    public function updateUserProfile(int $userId, array $profileData): User
    {
        // 包含更新用户资料的所有业务逻辑
        $user = $this->userRepository->findById($userId);
        if (!$user) {
            throw new \RuntimeException('User not found.');
        }
        // ... 更多更新前的业务校验
        return $this->userRepository->update($userId, $profileData);
    }
}

<?php

namespace App\Http\Controllers;

use App\Services\UserService;
use Illuminate\Http\Request;

class GoodUserController extends Controller
{
    private UserService $userService;

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

    /**
     * 创建一个新用户
     */
    public function createUser(Request $request)
    {
        // 1. 输入验证 (通常由FormRequest处理，此处简化)
        $validatedData = $request->validate([
            'name' => 'required|string|max:255',
            'email' => 'required|string|email|max:255',
            'password' => 'required|string|min:8',
        ]);

        // 2. 委托业务逻辑给服务层
        try {
            $user = $this->userService->registerUser($validatedData);
            return response()->json($user, 201);
        } catch (\InvalidArgumentException $e) {
            return response()->json(['message' => $e->getMessage()], 400);
        } catch (\Exception $e) {
            return response()->json(['message' => 'An error occurred during user registration.'], 500);
        }
    }
}