Setting up mongodb on Heroku with Node

Question

On my local host, I have the following Node code to setup a mongoDB database name "dbname":

users.js:

var MongoClient = require("mongodb").MongoClient,
    Connection = require("mongodb").Connection,
    Server = require("mongodb").Server;

Users = function(host, port) {
  var mongoClient = new MongoClient(new Server(host, port));
  mongoClient.open(function (){});
  this.db = mongoClient.db("dbname");
};

Users.prototype.getCollection = function (callback) {
  this.db.collection("users", function (error, users) {
    if (error) callback(error);
    else callback(null, users);
  });
};

Users.prototype.findAll = function (callback) {
  this.getCollection(function (error, users) {
    if (error) {
      callback(error);
    } else {
      users.find().toArray(function (error, results) {
        if (error) {
          callback(error);
        } else {
          callback(null,results);
        }
      });
    }
  });
}

// Bunch of other prototype functions...

exports.Users = Users;

I like to put the above database functionality in one file, and then in my main server file require that file as follows:

server.js:

var Users = require("./users").Users;
var users = new Users("localhost", 27017);
users.findAll(function (err, user) {
  // Do something
});

To have this working on localhost is pretty easy. In the command line, I just type the following:

$ mongod # to launch the database server
$ node server.js # to launch the web server

and it works fine. However, now I'm trying to push the whole thing onto Heroku with the mongolab addon

heroku addons:add mongolab

but the database is not running and I have no idea how to make it run. This tutorial explains how to setup mongodb with the mongolab URI, but that's not how my code works, I use a host and a port and I create a new server based on that. How should I change my code for it to work on the heroku app? I want to keep the database code in a separate file, with the prototype functions.

Community · Accepted Answer · 2017-05-23 12:03:22Z

2

Follow the example here at the "MongoClient.connect" section.

Essentially, you will need to change this part of the code:

Users = function(host, port) {
  var mongoClient = new MongoClient(new Server(host, port));
  mongoClient.open(function (){});
  this.db = mongoClient.db("dbname");
};

To use mongoClient.connect() instead of new MongoClient:

Users = function(url) {
  MongoClient.connect(url, function(err, db) {
    // Find better way to set this since this callback is asynchronous.
    this.db = db;
  });
};

If you are using node, I recommend using a library such as mongoose npm install mongoose to handle mongodb interactions. Look at my answer here for how to structure your schemas.

edited May 23, 2017 at 12:03

CommunityBot

11 silver badge

answered Dec 5, 2013 at 4:13

Xinzz

2,2521 gold badge14 silver badges26 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

cwarny Over a year ago

Thanks for the answer. But doesn't the fact that MongoClient.connect() is asynchronous make it impossible to structure my code the way it is? How would you write the prototype functions in this case?

Xinzz Over a year ago

That is a design decision you should try to adopt; Nodejs is only powerful BECAUSE it is asynchronous. If you try to do synchronous operations on its single-thread you will drive its performance to lower than all its alternatives. What I would do in your situation is to wrap all code inside the callback or install mongoose and follow how I structure my schemas here

cwarny · Accepted Answer · 2013-12-05 21:31:15Z

Helped by Xinzz's answer, here's the modified code, so that the mongodb database is initialized with a URI instead of host + port. That's how Heroku initializes the mongodb database, and that's why it wasn't working.

var mongodb = require("mongodb");

var MONGODB_URI = process.env.MONGOLAB_URI || process.env.MONGOHQ_URL || "mongodb://localhost", // Make sure to replace that URI with the one provided by MongoLab
    db,
    users;

mongodb.MongoClient.connect(MONGODB_URI, function (err, database) {
  if (err) throw err;
  db = database;
  users = db.collection("users");
  accounts = db.collection("accounts");
  var server = app.listen(process.env.PORT || 3000);
  console.log("Express server started on port %s", server.address().port);
});

The key here is to declare the variables db and users upfront, assign them a value in the asynchronous callback of the connect function of MongoClient and also start the app (app.listen(...)) in the same callback. Then later in the code I can do the following:

users.find().toArray(function (err, results) {
  // Do something
});

I also gave up on all these prototype functions, since they did not really add much.

Collectives™ on Stack Overflow

Setting up mongodb on Heroku with Node

2 Answers 2

2 Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related