treygriffith / mongoose-mixins

Mixins for Mongoose Models in an MVC environment

Mixins for Mongoose Models

Extend common functionality in an MVC environment

If your Node.js app is in an MVC format, where you have your models exposed as properties on a global models variable (e.g. models.Posts, models.Authors), you probably find yourself re-writing similar methods for every new model you add (e.g. models.Posts.createPost, models.Authors.createAuthor). With mixins, you can add functionality to your models while keeping your code DRY.

Installation

using Git

$ git clone git://github.com/treygriffith/mongoose-mixins.git node_modules/mongoose-mixins/

Usage

Before we start extending functionality, we set up our authors model in such a way that it can be extended

models = {};
models.Authors = {};

models.Authors.schema = new Schema({
	name: String,
	age: Number,
	interests: [String]
});
models.Authors.model = mongoose.model(models.Authors.schema);

Now that we have an environment that will support our mongoose mixins, we can extend their functionality

var mixins = require('mongoose-mixins');
mixins.extend(models.Authors, 'arrayFields');

Now we have some functionality exposed on our authors model! Let's try it out:

models.Authors.printAuthors = function() {
	this.getAll(function(err, authors) {
		if(err) {
			console.log(err);
			return;
		}
		console.log(authors);
	})	
};

We can partially apply our methods to make them more specific to authors.

var _;
models.Authors.getInterests = mixins.partial(models.Authors.getArray, _, 'interests'); // `_` must be undefined for this to work as expected

We can use our new partially applied function like so:

models.Authors.getInterests(author_id, function(err, interests) {
	console.log(author_id+" is interested in "+interests.join(', ')+"."); // prints 507f1f77bcf86cd799439011 is interested in books, writing.
});

Mixins

Mixins are separated into packages, that can be referenced by their string name. As of now, there are only two packages of mixins available in the core of mongoose-mixins:

1. 'basics' :
   • getAll - retrieve all the documents in a collection
   • getField - retrieve the contents of one field on one document in a collection
2. 'arrayFields' :
   • getAllArrays - retrieve and concatenate all the values in array fields on all the documents (de-duplicates)
   • getArray - retrieve an array on a document
   • addToArray - performs an addToSet operation, adding element or group of elements to an array field

You can easily add your own mixins by requiring them from the directory in which they reside:

mixins.extend(exports, require('/my_own_mixins/mixin'));

Notes

This is a new concept that I've found to be useful in my workflow to keep my code DRY, but it will probably change significantly as I become more accustomed to programming in this paradigm. To that end, pull requests are welcome to improve functionality, especially the form of new default mixin packages.