Mongo Mongoose Simple Tutorial Quick Start Code Example

How's that for a search engine friendly title? It's a combination of the things I tried as I started my experience with Mongo/mongoose that did not give me what I wanted. What I did get were all sorts of useful explanations and advice. What I did not get is a simple bit of working code to satisfy my Hello World needs.

The code below includes the lesson, 'use createConnection(), not connect()'. The former allows you to access the database from separate model classes without having to pass a connection object around. In the depths of the mongoose forums, the fancy guys admit that they prefer createConnection() so it's ok.

It also has my curried default test callback. I had a problem when I tested the example that required it so I left it in so you can solve whatever screws it up for you more easily.

I had two problems you might want to know about:

You will notice that the boilerplate has a peculiar model name (userTqTest). I built this example inside my real, working project. It turns out that Mongo does not forget old model definition stuff. I haven't quite worked out the details but the bottom line is that when I declared this model as User and saved, I got errors based on the validation in my previous, real model. That is, the mongoose model does not supersede the one inside Mongo itself. I got over it by, first, dropping the collection. Then, since I don't want you to have to drop your User collection, I changed it to a name that is very unlikely to collide with you database.

Second is one that you probably will notice instantly but, because I was focused so much on showing the simple syntax, I didn't think about right away is that these calls to save, get and delete are asynchronous. They are triggered in the right order but they are happening in whatever order Mongo takes care of it.

I didn't want to complicate the example with async or some other method to sequence the calls, so I didn't. This code definitely works if you run the three functions one at a time but give unpredictable results otherwise. My problem was that the delete fired before the save was complete leaving the record to give me a duplicate key error on the second pass.



        var mongoConnection = mongoose.createConnection("mongodb://localhost:27017/test");
        mongoConnection.on('error', function(err) {
            throw ("user code says, mongoose failed")

        var userSchema = new Schema({
            userName: {
                type: String,
                unique: true
            } /*obviously you'd have more properties*/

        var userAccessor = mongoConnection.model('UserTqTest', userSchema);

        var saveUser = function(user, callback) {
            /*you'd probably do some validation even though the mongoose will also validate
            you'd also wrap stuff in try/catch but that's not the point of this example.*/

            var newUser = new userAccessor(user);
  'saveUser' + '/' + user.userName));

        var getUser = function(user, callback) {
            var query = userAccessor.findOne(user);


        var deleteUser = function(user, callback) {
            userAccessor.remove(user, callback('deleteUser'));

        var callback = function(callingName) {
            return function(err, result) {
                console.log(callingName + '============');

            userName: 'tqwhite'
        }, callback);

            userName: 'tqwhite'
        }, callback);

            userName: 'tqwhite'
        }, callback);