使用mongoose和nodejs保存另一个文档的引用

const mongoose = require('mongoose');

// 定义User模型
const userSchema = new mongoose.Schema({
  name: String,
  age: Number,
});

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

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

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

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

user.save()
  .then((savedUser) => {
    const post = new Post({
      title: 'Hello World',
      content: 'This is my first post.',
      author: savedUser._id, // 引用User文档的_id
    });

    return post.save();
  })
  .then((savedPost) => {
    console.log('Post saved:', savedPost);
  })
  .catch((error) => {
    console.error('Error:', error);
  });

Post.findOne({ title: 'Hello World' })
  .populate('author') // 填充author字段
  .exec()
  .then((post) => {
    console.log('Post:', post);
    console.log('Author:', post.author);
  })
  .catch((error) => {
    console.error('Error:', error);
  });