JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://raw.github.com/documentcloud/underscore/master/underscore-min.js"></script>
<script src="http://documentcloud.github.com/backbone/backbone-min.js"></script>
<script src="https://raw.github.com/PaulUithol/Backbone-relational/master/backbone-relational.js"></script>
<label>relations</label> <textarea id="test"></textarea>

JavaScript

ModuleModel = Backbone.RelationalModel.extend({
    urlRoot: 'api/module',
    _radius: 50,
    relations: [{
        type: Backbone.HasMany,
        key: 'children',
        relatedModel: 'ModuleModel',
        collectionType: 'ModuleCollection',
        reverseRelation: {
            key: 'parent_id',
            includeInJSON: 'id'
        }}],
    url: function() {
        return this.id ? 'api/module/' + this.id : 'api/module';
    }
});

ModuleCollection = Backbone.Collection.extend({
    model: ModuleModel,
    url: 'api/modules'
});

var m = new ModuleModel();
_.each(m.relations, function (relation){
   $("#test").append(relation.key + "\n"); 
});