Identity Maps & BackboneBen Teese, Shine Technologies

Thursday, 14 February 13

Overview

The Problem

About Identity Maps

Backbone.IdentityMap

Thursday, 14 February 13

A Demo

Thursday, 14 February 13

Thursday, 14 February 13

Thursday, 14 February 13

Thursday, 14 February 13

The Problem

Roger

fetch

GET /suspects/1

Backend

fetch

GET /suspects

Collection ...

Todd

Michael

Roger

Thursday, 14 February 13

What we want

Roger

fetch

GET /suspects/1

Backend

fetch

GET /suspects

Collection ...

Todd

Michael

Thursday, 14 February 13

Identity Maps

Thursday, 14 February 13

Identity Map

Todd

Michael

Roger

Fred

Suspect:1

Suspect:2

Suspect:3

Suspect:4

......

Thursday, 14 February 13

Object Creation

if class and ID is in identity map return the cached objectelse create new object put it in identity map return the new objectend

Thursday, 14 February 13

Backbone.IdentityMap

Backbone ‘Plugin’

Overrides Model Constructor

Does not alter original Backbone

Thursday, 14 February 13

Before...

var Suspect = Backbone.Model.extend({ ...}); var Suspects = Backbone.Collection.extend({ model: Suspect, url: "/suspects"});

...

Thursday, 14 February 13

After...

var Suspect = Backbone.IdentityMap( Backbone.Model.extend({ ... })); var Suspects = Backbone.Collection.extend({ model: Suspect, url: "/suspects"});

...

Thursday, 14 February 13

Thursday, 14 February 13

How does it work?

Backbone.IdentityMap = function(originalConstructor) { var newConstructor = _.extend(function(attributes, options) { // Execute our identity map logic ... return newOrCachedObject; }, originalConstructor);

return newConstructor;};

Thursday, 14 February 13

How does it work with Backbone?

Thursday, 14 February 13

Backbone.Collection..._prepareModel: function(model, options) { options || (options = {}); if (!(model instanceof Model)) { var attrs = model; options.collection = this; model = new this.model(attrs, options); if (!model._validate(model.attributes, options)) { model = false; } } else if (!model.collection) { model.collection = this; } return model;},...

Thursday, 14 February 13

Backbone.Model

...// Create a new model with identical attributes to this one.clone: function() { return new this.constructor(this.attributes);},...

Thursday, 14 February 13

Caveats

Maps take space

Logout should clear the map

Tests should clear the map

Can’t subclass (yet)

Thursday, 14 February 13

github.com/shinetech

Thursday, 14 February 13