Check if mongoDB is connected

Question

I have mongoDB in my application.

I want to check if mongoDB is connected before I listen to the application.

Is this the best way to do this?

This is my server.js file:

var express = require('express'); var mongoDb = require('./mongoDb'); var app = express(); init(); function init() { if (mongoDb.isConnected()) { app.listen(8080, '127.0.0.1'); } else { console.log('error'); } } 

isConnected is executed by getDbObject . getDbObject connects to mongoDB and returns an object: (true / false), db (dbObject or error).

Then isConnected allow / reject using the associated property.

This is the mongoDb.js file:

 //lets require/import the mongodb native drivers. var mongodb = require('mongodb'); // Connection URL. This is where your mongodb server is running. var url = 'mongodb://localhost:27017/myDb'; var connectingDb; // promise //We need to work with "MongoClient" interface in order to connect to a mongodb server. var MongoClient = mongodb.MongoClient; init(); module.exports = { isConnected: isConnected } // Use connect method to connect to the Server function init() { connectingDb = new Promise( function (resolve, reject) { MongoClient.connect(url, function (err, db) { if (err) { console.log('Unable to connect to the mongoDB server. Error:', err); reject(err); } else { console.log('Connection established to', url); //Close connection //db.close(); resolve(db); } }); } ); } function getDbObject() { return connectingDb().then(myDb => { return { connected: true, db: myDb } } ) .catch(err => { return { connected: false, db: err } } ) } function isConnected() { return new Promise( function(resolve, reject) { var obj = getDbObject(); if (obj.connected == true) { console.log('success'); resolve(true); } else { console.log('error'); reject(false); } } ) } 

Any help appreciated!

Answer 1

There are several ways to configure your database. for a single (single) instance. You can use something like this

 Db.connect(configuration.url(), function(err, db) { assert.equal(null, err); 

if you have a shared environment with configuration servers and a few shards, you can use

 db.serverConfig.isConnected()