如何使用mongoose控制器路由将两个mongodb集合连接在一起？

const mongoose = require('mongoose');
const Schema = mongoose.Schema;

const UserSchema = new Schema({
  name: String,
  email: String,
  // 其他字段...
});

const PostSchema = new Schema({
  title: String,
  content: String,
  // 其他字段...
});

const User = mongoose.model('User', UserSchema);
const Post = mongoose.model('Post', PostSchema);

const User = require('../models/user');
const Post = require('../models/post');

// 获取所有用户和对应的帖子
const getUsersWithPosts = async (req, res) => {
  try {
    const users = await User.find().populate('posts');
    res.json(users);
  } catch (error) {
    res.status(500).json({ error: 'Internal server error' });
  }
};

// 创建新用户和帖子
const createUserWithPost = async (req, res) => {
  try {
    const { name, email, title, content } = req.body;

    const user = new User({ name, email });
    const post = new Post({ title, content });

    user.posts.push(post);
    await user.save();

    res.json({ message: 'User and post created successfully' });
  } catch (error) {
    res.status(500).json({ error: 'Internal server error' });
  }
};

module.exports = {
  getUsersWithPosts,
  createUserWithPost,
};

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

router.get('/users', controller.getUsersWithPosts);
router.post('/users', controller.createUserWithPost);

module.exports = router;

const express = require('express');
const app = express();
const router = require('./routes');

app.use(express.json());
app.use('/api', router);

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