Question

I recently started learning backbone and was wondering what would be the best way of grouping model attributes in a backbone model? I am thinking of having a specialized view that will handle a subset of the model’s attributes.

For example, if I have a car model, and I want to group all the information about the engine, so that I can pass these attributes to a view maybe? Something like car.engine_info

Car = Backbone.Model.extend({
    initialize: function() {
        this.engine_info = this._set_engine_info();
    }
    _set_engine_info: function() {
        return {displacement:this.get('displacement'), horsepower: this.get('horsepower')};
}

Answer 1

You should consider making multiple models, not return a separate set of data. That data won’t have the power of backbone behind it for event handling and updates. You are creating a new object that just has properties and values.

Instead make models for each component

A car has – An engine, features, etc.

Engine = Backbone.Model.extend({
  defaults: {
      cylinders: 4,
      horsepower: 180
  }
});

Features = Backbone.Model.extend({
    defaults: {
      powerwindows: true,
      airconditioning: true
    }
});

Then mixin the feature set into a car model by overriding the constructor

Car = Backbone.Model.extend({
    defaults: function () {
       return {
         engine: new Engine(),
         features: new Features()
       };
    },
    constructor: function ( attrs ) {
        attrs || ( attrs = {} );
        if ( attrs.engine ) {
            attrs.engine = new Engine( attrs.engine );
        } 
        // etc
        Backbone.Model.prototype.constructor.call( this, attrs );
    }
});

Another options would be to create a car and create some decorator functions that add the features, but frankly I prefer the method listed. Now you can have separate components listen to their own changes

var car = new Car({
    engine: { // props },
    features: { //props }
});

car.get( 'features' ).on( 'change:powerwindows', // some function, this );

The true power behind all of this is to separate responsibility of a car’s overall feature set. A car shouldn’t have to worry about all of it’s parts. Let the engine worry about the engine and let the features worry about the features.