如何在mongoDB地图集的现有记录上设置新属性

const MongoClient = require('mongodb').MongoClient;

// 连接到MongoDB数据库
MongoClient.connect('mongodb://localhost:27017', (err, client) => {
  if (err) throw err;

  // 选择目标地图集
  const db = client.db('mydb');
  const collection = db.collection('mycollection');

  // 查询现有记录
  const query = { name: 'John' };
  collection.findOne(query, (err, doc) => {
    if (err) throw err;

    // 更新记录
    const update = { $set: { age: 30 } };
    collection.updateOne(query, update, (err, result) => {
      if (err) throw err;

      console.log('Record updated successfully');
      client.close();
    });
  });
});