How to separate and re-use mongodb connection in Nodejs [duplicate]

manpreet Best Answer 3 years ago

I am trying to separate the connection to mongodb using nodejs and the current code looks like this in a file mongodb.js:

const mongoClient = require('mongodb').MongoClient;
const env = process.env.NODE_ENV || 'development';
const mongoDbUrl = require('../config/mongodb.json')[env];
let mongodb;

function connect(cb){
    mongoClient.connect(mongoDbUrl.url, (err, db) => {
        if (err) return "Could not connect to mongodb" ;
        else{
            console.log("Connection to mongodb is successful")
        }
        mongodb = db;
        cb();
    });
}
function get(){
    return mongodb;
}

function close(){
    mongodb.close();
}

module.exports = {
    connect,
    get,
    close,
};

and in other files for ex app.js I use it as:

const mongodb = require('../config/mongodb');
mongodb.connect(() => {
    mongodb.get().collection('tyk_organizations').find({}).toArray()
        .then((users) => {
            console.log('organizations ', users);
        });
});

manpreet 3 years ago

Try this:

// dbConnection.js
const MongoClient = require('mongodb').MongoClient;
const env = process.env.NODE_ENV || 'development';
const mongoDbUrl = require('../config/mongodb.json')[env];
let client;

module.exports = async () => {
  // this gives you client
  // Mongoclient.connect returns promise if no callback is passed
  try {
    client = await MongoClient.connect(mongoDbUrl.url, { useNewUrlParser: true });
  } catch (e) {
    console.log("Could not connect to mongodb");
  }
}

module.exports.get = () => client;

module.exports.close = () => client.close()

In your server or app

const connect = require('./dbConnection')
// establish connection
connect()

Elsewhere you can use like:

const { get } = require('./dbConnection')
// client is a promise
const client = get();
// then you can use like
client.db(dbName).collection(collName)...