Demo of Backbone associations

MilestoneModel = Backbone.Model.extend({
  initialize: function(attrs) {
    this.hasMany('Tasks', 'milestone_id');
  }
});


TaskModel = Backbone.Model.extend({
  initialize: function(attrs) {
    this.belongsTo('Milestones', 'milestone_id');
  }
});


var milestone = new MilestoneModel({ id: 1 });
var task = new TaskModel({ id: 2, milestone_id: 1});

milestone.tasks(); // Returns a Backbone collection of Tasks with milestone_id == 1

MilestoneCollection = Backbone.Collection.extend({
initialize: function() {
}
});

TaskModel = Backbone.Model.extend({
initialize: function() {
}
});

var milestone = new MilestoneCollection;
var task = new TaskModel({ id: 2, milestone_id: 1});
milestone.add(task);
milestone.models;