在一个mongoose查询中从2个单独的Mongo文档中获取信息

const mongoose = require('mongoose');

const userSchema = new mongoose.Schema({
  name: String,
  age: Number,
  posts: [{ type: mongoose.Schema.Types.ObjectId, ref: 'Post' }]
});

const postSchema = new mongoose.Schema({
  title: String,
  content: String,
  author: { type: mongoose.Schema.Types.ObjectId, ref: 'User' }
});

const User = mongoose.model('User', userSchema);
const Post = mongoose.model('Post', postSchema);

const user = new User({
  name: 'John',
  age: 25,
  posts: []
});

const post = new Post({
  title: 'Hello World',
  content: 'This is my first post',
  author: user._id
});

user.posts.push(post._id);

user.save();
post.save();

User.findOne({ name: 'John' })
  .populate('posts')
  .exec((err, user) => {
    if (err) {
      console.error(err);
      return;
    }

    console.log(user);
  });