如何在mongoose中通过引用对象属性检索对象

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

const userSchema = new Schema({
  name: String,
  age: Number,
  address: {
    type: Schema.Types.ObjectId,
    ref: 'Address'
  }
});

const addressSchema = new Schema({
  street: String,
  city: String,
  country: String
});

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

const address = new Address({
  street: '123 Main St',
  city: 'City',
  country: 'Country'
});

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

address.save(function(err) {
  if (err) {
    console.error('Error saving address:', err);
    return;
  }

  user.save(function(err) {
    if (err) {
      console.error('Error saving user:', err);
      return;
    }

    console.log('User saved successfully');
  });
});

User.findOne({ name: 'John' })
  .populate('address')
  .exec(function(err, user) {
    if (err) {
      console.error('Error finding user:', err);
      return;
    }

    console.log('User:', user);
  });