// 示例：Express.js路由设计
const express = require('express');
const router = express.Router();

// 用户资源
router.get('/users', userController.getAllUsers);
router.get('/users/:id', userController.getUserById);
router.post('/users', userController.createUser);
router.put('/users/:id', userController.updateUser);
router.delete('/users/:id', userController.deleteUser);

// 嵌套资源：用户的订单
router.get('/users/:userId/orders', orderController.getUserOrders);

// 用户控制器示例
exports.getUserById = async (req, res, next) => {
    try {
        const user = await userService.getUserById(req.params.id);
        if (!user) {
            return res.status(404).json({ error: 'User not found' });
        }
        res.json(user);
    } catch (error) {
        next(error);
    }
};

// 用户服务层
class UserService {
    constructor(userRepository) {
        this.userRepository = userRepository;
    }
    
    async getUserById(id) {
        // 业务逻辑处理
        const user = await this.userRepository.findById(id);
        if (!user) throw new Error('User not found');
        
        // 数据转换
        return {
            id: user.id,
            name: user.name,
            email: user.email,
            // 不返回密码等敏感信息
        };
    }
}