Mongoose如何在数组中填充模式

const mongoose = require('mongoose');

// 定义帖子模型
const postSchema = new mongoose.Schema({
  title: String,
  content: String
});

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

// 定义用户模型
const userSchema = new mongoose.Schema({
  name: String,
  posts: [{
    type: mongoose.Schema.Types.ObjectId,
    ref: 'Post'
  }]
});

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

const user = new User({ name: 'John' });

const post1 = new Post({ title: 'Post 1', content: 'Content 1' });
const post2 = new Post({ title: 'Post 2', content: 'Content 2' });

user.posts.push(post1);
user.posts.push(post2);

user.save();

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