How to reuse mongodb connection in node.js

Question

I'm using node-mongodb-native driver with mongodb to write a website. I have a question about how to open mongodb connection once, then use it in collection name users in `user.js` and collection name posts in `comment.js` I want to open db connection in `db.js` then to insert / save data for users and posts collection Currently code,my `db.js` ``` var Db = require('mongodb').Db, Connection = require('mongodb').Connection, Server = require('mongodb').Server; module.exports = new Db( 'blog', new Server('localhost', Connection.DEFAULT_PORT, {auto_reconnect: true}) ); ``` I used `db.js` in `user.js` as follow ``` var mongodb = require('./db'); function User(user){ this.name = user.name; this.password = user.password; this.email = user.email; }; module.exports = User; User.prototype.save = function(callback) {//save user information //document to save in db var user = { name: this.name, password: this.password, email: this.email }; mongodb.close(); //open mongodb database mongodb.open(fun…

Accepted Answer

You can connect once, and then reuse it as many times as you want:

```
var mongodb = require('mongodb');
var events = require('events');
var event = new events.EventEmitter();
var access = new mongodb.Server(host, port, { });
var client = null;

new mongodb.Db('YOUR DATABASE', access, { safe: true, auto_reconnect: true }).open(function (err, c) {
  if (!err) {
    client = c;
    console.log('database connected');
    event.emit('connect');
  } else {
    console.log('database connection error', err);
    event.emit('error');
  }
});

exports.get = function(fn) {
  if(client) {
    fn(client);
  } else {
    event.on('connect', function() {
      fn(client);
    });
  }
};
```

And then reuse it:

```
var db = require('./db');
var items;
db.get(function(client) {
  items = new mongodb.Collection(client, 'collection');
});

// then anywhere in your code
db.get(function() {
  // items.find({ ...
});
```

How to reuse mongodb connection in node.js

Solution

Problem