如何在nodejs中从外部文件加载MongoDb连接和查询

// config.js

module.exports = {
  mongoURI: 'mongodb://localhost:27017/mydatabase',
  query: {
    findUsers: function() {
      return db.collection('users').find();
    },
    insertUser: function(user) {
      return db.collection('users').insertOne(user);
    }
  }
};

// main.js

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

// 连接MongoDB数据库
MongoClient.connect(config.mongoURI, function(err, client) {
  if (err) {
    console.error('Failed to connect to MongoDB:', err);
    return;
  }

  console.log('Connected to MongoDB');

  // 获取数据库和集合对象
  const db = client.db();
  const collection = db.collection('users');

  // 执行查询操作
  config.query.findUsers().toArray(function(err, users) {
    if (err) {
      console.error('Failed to fetch users:', err);
      return;
    }

    console.log('Users:', users);
  });

  // 执行插入操作
  const newUser = { name: 'John', age: 25 };
  config.query.insertUser(newUser, function(err, result) {
    if (err) {
      console.error('Failed to insert user:', err);
      return;
    }

    console.log('User inserted:', result.ops[0]);
  });
});