如何在Nodejs中重用MongoDB连接

npm install mongodb

const MongoClient = require('mongodb').MongoClient;
const url = 'mongodb://localhost:27017/mydatabase';

let db;

MongoClient.connect(url, function(err, client) {
  if (err) throw err;
  console.log('Connected to MongoDB');
  db = client.db('mydatabase');
});

// 路由处理程序
function getUsers(req, res) {
  db.collection('users').find().toArray(function(err, result) {
    if (err) throw err;
    res.json(result);
  });
}

// 在其他模块中使用连接
db.collection('products').insertOne({ name: 'Product 1', price: 10 }, function(err, result) {
  if (err) throw err;
  console.log('Product inserted');
});

const MongoClient = require('mongodb').MongoClient;
const url = 'mongodb://localhost:27017/mydatabase';

let db;

function connect(callback) {
  MongoClient.connect(url, function(err, client) {
    if (err) throw err;
    console.log('Connected to MongoDB');
    db = client.db('mydatabase');
    callback();
  });
}

function close() {
  db.close(function(err) {
    if (err) throw err;
    console.log('Disconnected from MongoDB');
  });
}

module.exports = {
  connect,
  close,
  getDb: function() {
    return db;
  }
};