collection.js

App.collections.Menuitems = App.collections.Collection.extend({
	model : App.models.Menuitem,
	url : './api/menuitems',
	initialize: function(options){
		this.bind('reset', this.relationships); //collection loads so calculate relationships
	},
	
	relationships: function(){
		this.relations = _.groupBy(this.models, this.parent);
	},
	//return an array of root models
	root: function(){
		if(!this.relations) this.relationships();
		return this.relations[0];
	},
	//return an array of child models
	children: function(model){
		if(!this.relations) this.relationships();
		return (typeof this.relations[model.id] === 'undefined')? [] : this.relations[model.id];
	},
	//return parent_id or 0 if model.parent_id is undefined
	parent: function(model){
		var parent_id = model.get('parent_id');
		return (!parent_id)? 0: parent_id;
	}
});

index.html

	<script type="text/template" id="menu-item-template"><a id="menu-item-<%=id %>" href="<%=href %>" title="<%= title %>"><%=text %></a></script>
	<script type="text/template" id="menu-template"><h1>Menu</h1></script>

json.js

{"result":[
{"id":1,"href":"#\/","text":"Home","title":"Home"},
{"id":2,"href":"#\/persons","text":"Persons","title":"Person listing"},
{"id":4,"href":"#\/xxxx","text":"Broken link","title":""},
{"id":5,"href":"http:\/\/www.google.com","text":"www.google.com","title":"","parent_id":4},
{"id":6,"href":"http:\/\/www.ibm.com","text":"www.ibm.com","title":"","parent_id":5}
]}

Menu_view.js

App.views.Menu = App.views.View.extend({

	//define this.el, the wrapper element
	//id: '',
	tagName: 'div',
	className: 'menu',
	id: 'menu',
	
	//template function
	template: _.template($('#menu-template').html()),

	initialize: function(options) {

		if (!options.collection) throw 'no collection provided';

		//listen on non-this events
		_.bindAll(this, 'render');
		this.collection.bind('reset', this.render); //collection loaded
	},
	events: {
		//"click": "console"
	},
	close: function (){
		this.unbind();
		this.collection.unbind();
	},
	/***************************************
	 Render the view into the view's element
	****************************************/
	render: function (event){

		var content = this.template({}); //compiling template =  create DOM fragment
		var $el = $(this.el);
		
		$el.html(content);

		//render list menu
		$el.append(this.renderMenu(this.collection.root()));
		return this;
	},
	/**********************************************
	 Render list menu. Input is an array of models.
	 Output is DOM fragment.
	**********************************************/
	renderMenu: function(list){
		if(_.size(list) === 0) {return null;}
		var $dom = $('<ul></ul>');
		_.each(list, function(model){
			$dom.append(this.renderMenuItem(model));
			var kids = this.collection.children(model);
			$dom.find(':last').append(this.renderMenu(kids)); //recursive
		}, this);
		return $dom;

	},
	//	returns a DOM element fragment for a single menu item
	renderMenuItem: function (model){
		var view = new App.views.Menuitem({model: model});
		return view.render().el;
	},
	console: function (event){
		console.log(event, 'event');
	}
});

menuitem_view.js

App.views.Menuitem = App.views.View.extend({
	
	//define this.el, the wrapper element
	//el: $('#menu'),  //used in cases where the view wrapper already exists in the DOM
	tagName: 'li',
	//id: '',
	//className: 'menuitem',

	// Cache the template function for a single item.
	template: _.template($('#menu-item-template').html()),
	
	initialize: function(options) {
		_.bindAll(this, 'render'); 
		this.model.bind('change', this.render);
	},
	events: {
	},
	close: function (){
		this.unbind();
		this.model.unbind();
	},
	//render the view using a template
	render: function (event) {
		var content = this.template(this.model.toJSON());
		$(this.el).html(content);
		return this;
	}
});