帮我用 express+sequelize +mysql2分多个模块写一个demo

好的，下面是一个使用 Express.js、Sequelize 和 mysql2 实现的简单 demo，将其拆分为多个模块：

1. 安装依赖

npm install express sequelize mysql2

2. 创建数据库和数据表

CREATE DATABASE IF NOT EXISTS demo;
USE demo;

CREATE TABLE IF NOT EXISTS users (
  id INT(11) NOT NULL AUTO_INCREMENT,
  name VARCHAR(50) NOT NULL,
  email VARCHAR(50) NOT NULL,
  password VARCHAR(50) NOT NULL,
  PRIMARY KEY (id)
);

3. 创建 Sequelize 模型

在 models/user.js 文件中：

const { DataTypes } = require('sequelize');
const sequelize = require('../config/database');

const User = sequelize.define('User', {
  name: {
    type: DataTypes.STRING,
    allowNull: false,
  },
  email: {
    type: DataTypes.STRING,
    allowNull: false,
  },
  password: {
    type: DataTypes.STRING,
    allowNull: false,
  },
});

module.exports = User;

4. 创建 Express.js 应用

在 app.js 文件中：

const express = require('express');
const bodyParser = require('body-parser');
const userRoutes = require('./routes/userRoutes');

const app = express();

app.use(bodyParser.urlencoded({ extended: false }));
app.use(bodyParser.json());

app.use('/users', userRoutes);

app.listen(3000, () => console.log('Server running on port 3000'));

5. 创建 Sequelize 数据库连接

在 config/database.js 文件中：

const { Sequelize } = require('sequelize');

const sequelize = new Sequelize('demo', 'root', 'password', {
  host: 'localhost',
  dialect: 'mysql',
});

module.exports = sequelize;

6. 创建用户路由

在 routes/userRoutes.js 文件中：

const express = require('express');
const router = express.Router();
const UserController = require('../controllers/UserController');

router.get('/', UserController.getAllUsers);
router.get('/:id', UserController.getUserById);
router.post('/', UserController.createUser);
router.put('/:id', UserController.updateUser);
router.delete('/:id', UserController.deleteUser);

module.exports = router;

7. 创建用户控制器

在 controllers/UserController.js 文件中：

const User = require('../models/User');

exports.getAllUsers = async (req, res) => {
  const users = await User.findAll();
  res.json(users);
};

exports.getUserById = async (req, res) => {
  const user = await User.findByPk(req.params.id);
  res.json(user);
};

exports.createUser = async (req, res) => {
  const { name, email, password } = req.body;
  const user = await User.create({ name, email, password });
  res.json(user);
};

exports.updateUser = async (req, res) => {
  const { name, email, password } = req.body;
  await User.update({ name, email, password }, { where: { id: req.params.id } });
  res.json({ message: 'User updated successfully.' });
};

exports.deleteUser = async (req, res) => {
  await User.destroy({ where: { id: req.params.id } });
  res.json({ message: 'User deleted successfully.' });
};

现在，我们已经将应用拆分为多个模块，可以通过运行 `node app.js` 启动应用。然后可以使用 Postman 或其他工具测试 API。