Backbone.Brace

This package tracks the original project released by Atlassian on Bitbucket, which has never been released as a library.

Brace is an extension to Backbone that adds mixins and self-documenting attributes & events.

Self-documenting attributes and events

Brace allows:

• namedEvents on Models, Collections, Views and Routers, which is a collection of exposed events
• namedAttributes on Models, which is a collection of exposed attributes - i.e. a model schema

Both namedEvents and namedAttributes are arrays of strings. namedAttributes can also be an object.

var Person = Brace.Model.extend({
	namedAttributes: ["name"],
	namedEvents: ["sleep"]
});

For each attribute in namedAttributes, get[Attribute] and set[Attribute] methods are generated:

var person = new Person();
person.setName("Tim");
person.getName() // Returns "Tim"

Backbone models' get() and set() validate attributes:

person.get("name"); // ok
person.set("name", "Timmy"); // ok
person.set({
	name: "Timothy"
}); // ok

person.get("lost"); // throws exception
person.set("lost", "frequently"); // throws exception
person.set({
	lost: "frequently"
}); // throws exception

The types of your namedAttributes are validated and coerced when namedAttributes is an object:

var People = Brace.Collection.extend();
var Person = Brace.Model.extend({
	namedAttributes: {
		name : "string", // validate primitives with typeof
		otherNames : [ "string" ], // validate typed array-likes
		birthDate : Date, // validate arbitrary constructors with instanceof,
							// calls `new constructor(rawValue)` if necessary
		children : People, // validate Backbone.Collections,
							// coerces arrays and contained models if necessary
		attributes : Array, // validate untyped array-likes
		metadata : null || undefined || false // skip validation completely
	}
});
People.model = Person;

var person = new Person({ name : 'Enigma' }); // ok
person.set('name', null); // ok
person.set('name', 'Nazim'); // ok
person.set('name', 4); // throws exception

person.set('otherNames', [ 'Ahmed' ]); // ok
person.set('otherNames', [ 1, 4 ]); // throws exception

person.set('attributes', [ 'one', 2, {} ]); // ok
person.set('attributes', 'The Dude'); // throws exception

person.set('birthDate', 'Mar 12 1960'); // ok
person.get('birthDate').toString(); // "Sat Mar 12 1960 00:00:00 GMT+1100 (AUS Eastern Daylight Time)"

person.set('children', [ { name : 'Adam' }, { name : 'Mariam' }, { name : 'Sarah' } ]); // ok
person.get('children'); // returns People instance containing three Person models.

For each event in namedEvents, on[Event] and trigger[Event] methods are generated:

person.onSleep(function(dream) { console.log("Dreaming about " + dream); } );
person.triggerSleep("Unicorns");

Mixins

Brace allows a mixins property on models, views, collections and routers:

var Loggable = {
	log: function(msg) {
		console.log(msg);
	}
};

var PersonView = Brace.View.extend({
	mixins: [Loggable],

	initialize: function() {
		this.log("Initialized");
	}
});

Mixins with Backbone

namedAttributes and namedEvents in mixins are respected:

var Selectable = {
	namedAttributes: ["selected"],
	namedEvents: ["select"],

	initialize: function() {
		this.on("change:selected", _.bind(function(model, selected) {
			if (selected) {
				this.triggerSelect();
			}
		}, this));
	}
};

var Person = Brace.Model.extend({
	mixins: [Selectable]
});

var person = new Person();

person.onSelect(function() { console.log("Person was selected"); });
person.setSelected(true);
person.getSelected();
person.triggerSelect();

Additionally, Brace composes

• initialize() on all objects, and
• defaults and validate() on models

All other name clashes between mixins fail violently and forcefully at class declaration time (not at instance construction time).

var Runnable = {
	run: function() {}
};

var RunModel = Brace.Model.extend({
	mixins: [Runnable],
	run: function() {}
}); // throws "Mixin error: class already has property 'run' defined"