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backbone/index.html
Jeremy Ashkenas d2ba331184 Backbone.js 0.1.2
2010-10-19 11:44:07 -04:00

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<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="content-type" content="text/html;charset=UTF-8" />
<meta http-equiv="X-UA-Compatible" content="chrome=1">
<title>Backbone.js</title>
<style>
body {
font-size: 14px;
line-height: 22px;
font-family: Helvetica Neue, Helvetica, Arial;
background: #f4f4f4 url(docs/images/background.png);
}
.interface {
font-family: "Lucida Grande", "Lucida Sans Unicode", Helvetica, Arial, sans-serif !important;
}
div#sidebar {
background: #fff;
position: fixed;
top: 0; left: 0; bottom: 0;
width: 200px;
overflow-y: auto;
overflow-x: hidden;
padding: 15px 0 30px 30px;
border-right: 1px solid #ddd;
box-shadow: 0 0 20px #ccc; -webkit-box-shadow: 0 0 20px #ccc; -moz-box-shadow: 0 0 20px #ccc;
}
a.toc_title, a.toc_title:visited {
display: block;
color: black;
font-weight: bold;
margin-top: 15px;
}
div.toc_title:hover {
text-decoration: underline;
}
ul.toc_section {
font-size: 11px;
line-height: 14px;
margin: 5px 0 0 0;
padding-left: 0px;
list-style-type: none;
font-family: Lucida Grande;
}
.toc_section li {
cursor: pointer;
margin: 0 0 3px 0;
}
.toc_section li a {
color: black;
}
div.container {
position: relative;
width: 550px;
margin: 40px 0 50px 260px;
}
div.run {
position: absolute;
right: 15px;
width: 26px; height: 18px;
background: url('docs/images/arrows.png') no-repeat -26px 0;
}
div.run:active {
background-position: -51px 0;
}
p, div.container ul {
margin: 20px 0;
width: 550px;
}
div.container ul {
list-style: circle;
font-size: 12px;
padding-left: 15px;
}
a, a:visited {
color: #444;
text-decoration: none;
}
a:active, a:hover {
color: #000;
text-decoration: underline;
}
a img {
border: 0;
}
h1, h2, h3, h4, h5, h6 {
padding-top: 20px;
}
h2 {
font-size: 20px;
}
b.header {
font-size: 16px;
line-height: 30px;
}
span.alias {
font-size: 14px;
font-style: italic;
margin-left: 20px;
}
table {
margin: 15px 0 0; padding: 0;
}
tr, td {
margin: 0; padding: 0;
}
td {
padding: 0px 15px 5px 0;
}
code, pre, tt {
font-family: Monaco, Consolas, "Lucida Console", monospace;
font-size: 12px;
line-height: 18px;
}
tt {
padding: 0px 3px;
background: #fff;
border: 1px solid #ddd;
zoom: 1;
}
code {
margin-left: 20px;
}
pre {
font-size: 12px;
padding: 2px 0 2px 15px;
border: 4px solid #bbb; border-top: 0; border-bottom: 0;
margin: 0px 0 30px;
}
</style>
</head>
<body>
<div id="sidebar" class="interface">
<a class="toc_title" href="#">
Backbone.js
</a>
<a class="toc_title" href="#Introduction">
Introduction
</a>
<a class="toc_title" href="#Events">
Events
</a>
<ul class="toc_section">
<li>– <a href="#Events-bind">bind</a></li>
<li>– <a href="#Events-unbind">unbind</a></li>
<li>– <a href="#Events-trigger">trigger</a></li>
</ul>
<a class="toc_title" href="#Model">
Model
</a>
<ul class="toc_section">
<li>– <a href="#Model-extend">extend</a></li>
<li>– <a href="#Model-constructor">constructor / initialize</a></li>
<li>– <a href="#Model-get">get</a></li>
<li>– <a href="#Model-set">set</a></li>
<li>– <a href="#Model-unset">unset</a></li>
<li>– <a href="#Model-id">id</a></li>
<li>– <a href="#Model-cid">cid</a></li>
<li>– <a href="#Model-attributes">attributes</a></li>
<li>- <a href="#Model-toJSON">toJSON</a></li>
<li>– <a href="#Model-fetch">fetch</a></li>
<li>– <a href="#Model-save">save</a></li>
<li>– <a href="#Model-destroy">destroy</a></li>
<li>– <a href="#Model-validate">validate</a></li>
<li>– <a href="#Model-url">url</a></li>
<li>– <a href="#Model-clone">clone</a></li>
<li>– <a href="#Model-isNew">isNew</a></li>
<li>– <a href="#Model-change">change</a></li>
<li>– <a href="#Model-hasChanged">hasChanged</a></li>
<li>– <a href="#Model-changedAttributes">changedAttributes</a></li>
<li>– <a href="#Model-previous">previous</a></li>
<li>– <a href="#Model-previousAttributes">previousAttributes</a></li>
</ul>
<a class="toc_title" href="#Collection">
Collection
</a>
<ul class="toc_section">
<li>– <a href="#Collection-extend">extend</a></li>
<li>– <a href="#Collection-model">model</a></li>
<li>– <a href="#Collection-constructor">constructor / initialize</a></li>
<li>– <a href="#Collection-models">models</a></li>
<li>– <a href="#Collection-Underscore-Methods"><b>Underscore Methods (24)</b></a></li>
<li>– <a href="#Collection-add">add</a></li>
<li>– <a href="#Collection-remove">remove</a></li>
<li>– <a href="#Collection-get">get</a></li>
<li>– <a href="#Collection-getByCid">getByCid</a></li>
<li>– <a href="#Collection-at">at</a></li>
<li>– <a href="#Collection-length">length</a></li>
<li>– <a href="#Collection-comparator">comparator</a></li>
<li>– <a href="#Collection-sort">sort</a></li>
<li>– <a href="#Collection-pluck">pluck</a></li>
<li>– <a href="#Collection-url">url</a></li>
<li>– <a href="#Collection-fetch">fetch</a></li>
<li>– <a href="#Collection-refresh">refresh</a></li>
<li>– <a href="#Collection-create">create</a></li>
</ul>
<a class="toc_title" href="#Sync">
Sync
</a>
<ul class="toc_section">
<li>– <a href="#Sync">Backbone.sync</a></li>
</ul>
<a class="toc_title" href="#View">
View
</a>
<ul class="toc_section">
<li>– <a href="#View-extend">extend</a></li>
<li>– <a href="#View-constructor">constructor / initialize</a></li>
<li>– <a href="#View-el">el</a></li>
<li>– <a href="#View-jQuery">$ (jQuery)</a></li>
<li>– <a href="#View-render">render</a></li>
<li>– <a href="#View-make">make</a></li>
<li>– <a href="#View-handleEvents">handleEvents</a></li>
</ul>
<a class="toc_title" href="#changelog">
Change Log
</a>
</div>
<div class="container">
<p>
<img style="width: 385px; height: 126px;" src="docs/images/backbone.png" alt="Backbone.js" />
</p>
<p>
<a href="http://github.com/documentcloud/backbone/">Backbone</a>
supplies structure to JavaScript-heavy applications by providing <b>models</b> with
key-value binding and custom events, <b>collections</b> with a rich API of enumerable functions,
<b>views</b> with declarative event handling, and connects it all to your
existing application over a RESTful JSON interface.
</p>
<p>
The project is <a href="http://github.com/documentcloud/backbone/">hosted on GitHub</a>,
and the <a href="docs/backbone.html">annotated source code</a> is available,
as well as an online <a href="test/test.html">test suite</a>.
</p>
<p>
<i>
Backbone is an open-source component of
<a href="http://documentcloud.org/">DocumentCloud</a>.
</i>
</p>
<h2 id="downloads">
Downloads &amp; Dependencies
<span style="padding-left: 7px; font-size:11px; font-weight: normal;" class="interface">(Right-click, and use "Save As")</span>
</h2>
<table>
<tr>
<td><a href="backbone.js">Development Version (0.1.2)</a></td>
<td><i>23.8kb, Uncompressed with Comments</i></td>
</tr>
<tr>
<td><a href="backbone-min.js">Production Version (0.1.2)</a></td>
<td><i>2.6kb, Packed and Gzipped</i></td>
</tr>
</table>
<p>
Backbone's only hard dependency is
<a href="http://documentcloud.github.com/underscore/">Underscore.js</a>.
For RESTful persistence, and DOM manipulation with
<a href="#View">Backbone.View</a>,
it's highly recommended to include <a href="http://jquery.com">jQuery</a>,
and <a href="http://www.json.org/json2.js">json2.js</a>
(both of which you may already have on the page).
</p>
<h2 id="Introduction">Introduction</h2>
<p>
When working on a web application that involves a lot of JavaScript, one
of the first things you learn is to stop tying your data to the DOM. It's all
too easy to create JavaScript applications that end up as tangled piles of
jQuery selectors and callbacks, all trying frantically to keep data in
sync between the HTML UI, your JavaScript logic, and the database on your
server. For rich client-side applications, a more structured approach
is helpful.
</p>
<p>
With Backbone, you represent your data as
<a href="#Model">Models</a>, which can be created, validated, destroyed,
and saved to the server. Whenever a UI action causes an attribute of
a model to change, the model triggers a <i>"change"</i> event; all
the <a href="#View">Views</a> that display the model's data are notified of the
event, causing them to re-render. You don't have to write the glue
code that looks into the DOM to find an element with a specific <i>id</i>,
and update the HTML manually
&mdash; when the model changes, the views simply update themselves.
</p>
<p>
<i>How is this different than
<a href="http://www.sproutcore.com/">SproutCore</a> or
<a href="http://cappuccino.org/">Cappuccino</a>?
</i>
</p>
<p>
This question is frequently asked, and all three projects apply general
<a href="http://en.wikipedia.org/wiki/Model–View–Controller">Model-View-Controller</a>
principles to JavaScript applications. However, there isn't much basis
for comparison. SproutCore and Cappuccino provide rich UI widgets, vast
core libraries, and determine the structure of your HTML for you.
Both frameworks measure in the hundreds of kilobytes when packed and
gzipped, and megabytes of JavaScript, CSS, and images when loaded in the browser
&mdash; there's a lot of room underneath for libraries of a more moderate scope.
Backbone is a <i>2 kilobyte</i> include that provides
just the core concepts of models, events, collections, views, and persistence.
</p>
<p>
Many of the examples that follow are runnable. Click the <i>play</i> button
to execute them.
</p>
<h2 id="Events">Backbone.Events</h2>
<p>
<b>Events</b> is a module that can be mixed in to any object, giving the
object the ability to bind and trigger custom named events. Events do not
have to be declared before they are bound, and may take passed arguments.
For example:
</p>
<pre class="runnable">
var object = {};
_.extend(object, Backbone.Events);
object.bind("alert", function(msg) {
alert("Triggered " + msg);
});
object.trigger("alert", "an event");
</pre>
<p id="Events-bind">
<b class="header">bind</b><code>object.bind(event, callback)</code>
<br />
Bind a <b>callback</b> function to an object. The callback will be invoked
whenever the <b>event</b> (specified by an arbitrary string identifier) is fired.
If you have a large number of different events on a page, the convention is to use colons to
namespace them: <tt>"poll:start"</tt>, or <tt>"change:selection"</tt>
</p>
<p>
Callbacks bound to the special
<tt>"all"</tt> event will be triggered when any event occurs, and are passed
the name of the event as the first argument. For example, to proxy all events
from one object to another:
</p>
<pre>
proxy.bind("all", function(eventName) {
object.trigger(eventName);
});
</pre>
<p id="Events-unbind">
<b class="header">unbind</b><code>object.unbind([event], [callback])</code>
<br />
Remove a previously-bound <b>callback</b> function from an object. If no
callback is specified, all callbacks for the <b>event</b> will be
removed. If no event is specified, <i>all</i> event callbacks on the object
will be removed.
</p>
<pre>
object.unbind("change", onChange); // Removes just the onChange callback.
object.unbind("change"); // Removes all "change" callbacks.
object.unbind(); // Removes all callbacks on object.
</pre>
<p id="Events-trigger">
<b class="header">trigger</b><code>object.trigger(event, [*args])</code>
<br />
Trigger callbacks for the given <b>event</b>. Subsequent arguments to
<b>trigger</b> will be passed along to the event callbacks.
</p>
<h2 id="Model">Backbone.Model</h2>
<p>
<b>Models</b> are the heart of any JavaScript application, containing
the interactive data as well as a large part of the logic surrounding it:
conversions, validations, computed properties, and access control. You
extend <b>Backbone.Model</b> with your domain-specific methods, and
<b>Model</b> provides a basic set of functionality for managing changes.
</p>
<p>
The following is a contrived example, but it demonstrates defining a model
with a custom method, setting an attribute, and firing an event keyed
to changes in that specific attribute.
After running this code once, <tt>sidebar</tt> will be
available in your browser's console, so you can play around with it.
</p>
<pre class="runnable">
var Sidebar = Backbone.Model.extend({
promptColor: function() {
var cssColor = prompt("Please enter a CSS color:");
this.set({color: cssColor});
}
});
window.sidebar = new Sidebar;
sidebar.bind('change:color', function(model, color) {
$('#sidebar').css({background: color});
});
sidebar.set({color: 'white'});
sidebar.promptColor();
</pre>
<p id="Model-extend">
<b class="header">extend</b><code>Backbone.Model.extend(properties, [classProperties])</code>
<br />
To create a <b>Model</b> class of your own, you extend <b>Backbone.Model</b>
and provide instance <b>properties</b>, as well as optional
<b>classProperties</b> to be attached directly to the constructor function.
</p>
<p>
<b>extend</b> correctly sets up the prototype chain, so subclasses created
with <b>extend</b> can be further extended and subclassed as far as you like.
</p>
<pre>
var Note = Backbone.Model.extend({
initialize: function() { ... },
author: function() { ... },
allowedToEdit: function(account) { ... },
coordinates: function() { ... }
});
</pre>
<p>
<i>
Brief aside on </i><tt>super</tt>: <i>JavaScript does not provide
a simple way to call super &mdash; the function of the same name defined
higher on the prototype chain. If you override a core function like
</i><tt>set</tt>,<i> or </i><tt>save</tt>, <i>and you want to invoke the
parent object's implementation, you'll have to explicitly call it, along these lines:
</i>
</p>
<pre>
var Note = Backbone.Model.extend({
set: function(attributes, options) {
Backbone.Model.prototype.set.call(this, attributes, options);
...
}
});
</pre>
<p id="Model-constructor">
<b class="header">constructor / initialize</b><code>new Model([attributes])</code>
<br />
When creating an instance of a model, you can pass in the initial values
of the <b>attributes</b>, which will be <a href="#Model-set">set</a> on the
model. If you define an <b>initialize</b> function, it will be invoked when
the model is created.
</p>
<pre>
new Book({
title: "One Thousand and One Nights",
author: "Scheherazade"
});
</pre>
<p id="Model-get">
<b class="header">get</b><code>model.get(attribute)</code>
<br />
Get the current value of an attribute from the model. For example:
<tt>note.get("title")</tt>
</p>
<p id="Model-set">
<b class="header">set</b><code>model.set(attributes, [options])</code>
<br />
Set a hash of attributes (one or many) on the model. If any of the attributes
change the models state, a <tt>"change"</tt> event will be fired, unless
<tt>{silent: true}</tt> is passed as an option.
</p>
<pre>
note.set({title: "October 12", content: "Lorem Ipsum Dolor Sit Amet..."});
</pre>
<p>
If the model has a <a href="#Model-validate">validate</a> method,
it will be validated before the attributes are set, no changes will
occur if the validation fails, and <b>set</b> will return <tt>false</tt>.
You may also pass an <tt>error</tt>
callback in the options, which will be invoked instead of triggering an
<tt>"error"</tt> event, should validation fail.
</p>
<p id="Model-unset">
<b class="header">unset</b><code>model.unset(attribute, [options])</code>
<br />
Remove an attribute by deleting it from the internal attributes hash.
Fires a <tt>"change"</tt> event unless <tt>silent</tt> is passed as an option.
</p>
<p id="Model-id">
<b class="header">id</b><code>model.id</code>
<br />
A special property of models, the <b>id</b> is an arbitrary string
(integer id or UUID). If you set the <b>id</b> in the
attributes hash, it will be copied onto the model as a direct property.
Models can be retrieved by id from collections, and the id is used to generate
model URLs by default.
</p>
<p id="Model-cid">
<b class="header">cid</b><code>model.cid</code>
<br />
A special property of models, the <b>cid</b> or client id is a unique identifier
automatically assigned to all models when they're first created. Client ids
are handy when the model has not yet been saved to the server, and does not
yet have its eventual true <b>id</b>, but already needs to be visible in the UI.
Client ids take the form: <tt>c1, c2, c3 ...</tt>
</p>
<p id="Model-attributes">
<b class="header">attributes</b><code>model.attributes</code>
<br />
The <b>attributes</b> property is the internal hash containing the model's
state. Please use <a href="#Model-set">set</a> to update the attributes instead of modifying
them directly. If you'd like to retrieve and munge a copy of the model's
attributes, use <a href="#Model-toJSON">toJSON</a> instead.
</p>
<p id="Model-toJSON">
<b class="header">toJSON</b><code>model.toJSON()</code>
<br />
Return a copy of the model's <a href="#Model-attributes">attributes</a> for JSON stringification.
This can be used for persistence, serialization, or for augmentation before
being handed off to a view. The name of this method is a bit confusing, as
it doesn't actually return a JSON string &mdash; but I'm afraid that it's
the way that the <a href="https://developer.mozilla.org/en/JSON#toJSON()_method">JavaScript API for <b>JSON.stringify</b> works</a>.
</p>
<pre class="runnable">
var artist = new Backbone.Model({
firstName: "Wassily",
lastName: "Kandinsky"
});
artist.set({birthday: "December 16, 1866"});
alert(JSON.stringify(artist));
</pre>
<p id="Model-fetch">
<b class="header">fetch</b><code>model.fetch([options])</code>
<br />
Refreshes the model's state from the server. Useful if the model has never
been populated with data, or if you'd like to ensure that you have the
latest server state. A <tt>"change"</tt> event will be triggered if the
server's state differs from the current attributes. Accepts
<tt>success</tt> and <tt>error</tt> callbacks in the options hash, which
are passed <tt>(model, response)</tt> as arguments.
</p>
<pre>
// Poll every 10 seconds to keep the channel model up-to-date.
setInterval(function() {
channel.fetch();
}, 10000);
</pre>
<p>
<i>
<b>Cautionary Note:</b> When fetching or saving a model, make sure that the model is part of
a collection with a <a href="#Collection-url">url</a> property specified,
or that the model itself has a complete <a href="#Model-url">url</a> function
of its own, so that the request knows where to go.
</i>
</p>
<p id="Model-save">
<b class="header">save</b><code>model.save(attributes, [options])</code>
<br />
Save a model to your database (or alternative persistence layer),
by delegating to <a href="#Sync">Backbone.sync</a>. If the model has a <a href="#Model-validate">validate</a>
method, and validation fails, the model will not be saved. If the model
<a href="#Model-isNew">isNew</a>, the save will be a <tt>"create"</tt>
(HTTP <tt>POST</tt>), if the model already
exists on the server, the save will be an <tt>"update"</tt> (HTTP <tt>PUT</tt>). Accepts
<tt>success</tt> and <tt>error</tt> callbacks in the options hash, which
are passed <tt>(model, response)</tt> as arguments. The <tt>error</tt> callback will
also be invoked if the model has a <tt>validate</tt> method, and validation fails.
</p>
<p>
In the following example, notice how because the model has never been
saved previously, our overridden version of <tt>Backbone.sync</tt> receives a <tt>"create"</tt> request.
</p>
<pre class="runnable">
Backbone.sync = function(method, model) {
alert(method + ": " + JSON.stringify(model));
};
var book = new Backbone.Model({
title: "The Rough Riders",
author: "Theodore Roosevelt"
});
book.save();
</pre>
<p id="Model-destroy">
<b class="header">destroy</b><code>model.destroy([options])</code>
<br />
Destroys the model on the server by delegating an HTTP <tt>DELETE</tt>
request to <a href="#Sync">Backbone.sync</a>. Accepts
<tt>success</tt> and <tt>error</tt> callbacks in the options hash.
</p>
<pre>
book.destroy({success: function(model, response) {
...
}});
</pre>
<p id="Model-validate">
<b class="header">validate</b><code>model.validate(attributes)</code>
<br />
This method is left undefined, and you're encouraged to override it with
your custom validation logic, if you have any that can be performed
in JavaScript. <b>validate</b> is called before <tt>set</tt> and
<tt>save</tt>, and is passed the attributes that are about to be updated.
If the model and attributes are valid, don't return anything from <b>validate</b>;
if the attributes are invalid, return an error of your choosing. It
can be as simple as a string error message to be displayed, or a complete
error object that describes the error programmatically. <tt>set</tt> and
<tt>save</tt> will not continue if <b>validate</b> returns an error.
Failed validations trigger an <tt>"error"</tt> event.
</p>
<pre class="runnable">
var Chapter = Backbone.Model.extend({
validate: function(attrs) {
if (attrs.end < attrs.start) {
return "can't end before it starts";
}
}
});
var one = new Chapter({
title : "Chapter One: The Beginning"
});
one.bind("error", function(model, error) {
alert(model.get("title") + " " + error);
});
one.set({
start: 15,
end: 10
});
</pre>
<p>
<tt>"error"</tt> events are useful for providing coarse-grained error
messages at the model or collection level, but if you have a specific view
that can better handle the error, you may override and suppress the event
by passing an <tt>error</tt> callback directly:
</p>
<pre>
account.set({access: "unlimited"}, {
error: function(model, error) {
alert(error);
}
});
</pre>
<p id="Model-url">
<b class="header">url</b><code>model.url()</code>
<br />
Returns the relative URL where the model's resource would be located on
the server. If your models are located somewhere else, override this method
with the correct logic. Generates URLs of the form: <tt>"/[collection]/[id]"</tt>.
</p>
<p>
Delegates to <a href="#Collection-url">Collection#url</a> to generate the
URL, so make sure that you have it defined.
A model with an id of <tt>101</tt>, stored in a
<a href="#Collection">Backbone.Collection</a> with a <tt>url</tt> of <tt>"/notes"</tt>,
would have this URL: <tt>"/notes/101"</tt>
</p>
<p id="Model-clone">
<b class="header">clone</b><code>model.clone()</code>
<br />
Returns a new instance of the model with identical attributes.
</p>
<p id="Model-isNew">
<b class="header">isNew</b><code>model.isNew()</code>
<br />
Has this model been saved to the server yet? If the model does not yet have
an <tt>id</tt>, it is considered to be new.
</p>
<p id="Model-change">
<b class="header">change</b><code>model.change()</code>
<br />
Manually trigger the <tt>"change"</tt> event.
If you've been passing <tt>{silent: true}</tt> to the <a href="#Model-set">set</a> function in order to
aggregate rapid changes to a model, you'll want to call <tt>model.change()</tt>
when you're all finished.
</p>
<p id="Model-hasChanged">
<b class="header">hasChanged</b><code>model.hasChanged([attribute])</code>
<br />
Has the model changed since the last <tt>"change"</tt> event? If an <b>attribute</b>
is passed, returns <tt>true</tt> if that specific attribute has changed.
</p>
<pre>
book.bind("change", function() {
if (book.hasChanged("title")) {
...
}
});
</pre>
<p id="Model-changedAttributes">
<b class="header">changedAttributes</b><code>model.changedAttributes([attributes])</code>
<br />
Retrieve a hash of only the model's attributes that have changed. Optionally,
an external <b>attributes</b> hash can be passed in, returning
the attributes in that hash which differ from the model. This can be used
to figure out which portions of a view should be updated, or what calls
need to be made to sync the changes to the server.
</p>
<p id="Model-previous">
<b class="header">previous</b><code>model.previous(attribute)</code>
<br />
During a <tt>"change"</tt> event, this method can be used to get the
previous value of a changed attribute.
</p>
<pre class="runnable">
var bill = new Backbone.Model({
name: "Bill Smith"
});
bill.bind("change:name", function(model, name) {
alert("Changed name from " + bill.previous("name") + " to " + name);
});
bill.set({name : "Bill Jones"});
</pre>
<p id="Model-previousAttributes">
<b class="header">previousAttributes</b><code>model.previousAttributes()</code>
<br />
Return a copy of the model's previous attributes. Useful for getting a
diff between versions of a model, or getting back to a valid state after
an error occurs.
</p>
<h2 id="Collection">Backbone.Collection</h2>
<p>
Collections are ordered sets of models. You can bind callbacks to be notified
when any model in the collection is changed, listen for <tt>"add"</tt> and
<tt>"remove"</tt> events, <tt>fetch</tt> the collection from the server,
and use a full suite of
<a href="#Collection-Underscore-Methods">Underscore.js methods</a>.
</p>
<p id="Collection-extend">
<b class="header">extend</b><code>Backbone.Collection.extend(properties, [classProperties])</code>
<br />
To create a <b>Collection</b> class of your own, extend <b>Backbone.Collection</b>,
providing instance <b>properties</b>, as well as optional <b>classProperties</b> to be attached
directly to the collection's constructor function.
</p>
<p id="Collection-model">
<b class="header">model</b><code>collection.model</code>
<br />
Override this property to specify the model class that the collection
contains. If defined, you can pass raw attributes objects (and arrays) to
<a href="#Collection-add">add</a>, <a href="#Collection-create">create</a>,
and <a href="#Collection-refresh">refresh</a>, and the attributes will be
converted into a model of the proper type.
</p>
<pre>
var Library = Backbone.Collection.extend({
model: Book
});
</pre>
<p id="Collection-constructor">
<b class="header">constructor / initialize</b><code>new Collection([models], [options])</code>
<br />
When creating a Collection, you may choose to pass in the initial array of <b>models</b>.
The collection's <a href="#Collection-comparator">comparator</a> function
may be included as an option. If you define an <b>initialize</b> function, it will be
invoked when the collection is created.
</p>
<pre>
var tabs = new TabSet([tab1, tab2, tab3]);
</pre>
<p id="Collection-models">
<b class="header">models</b><code>collection.models</code>
<br />
Raw access to the JavaScript array of models inside of the collection. Usually you'll
want to use <tt>get</tt>, <tt>at</tt>, or the <b>Underscore methods</b>
to access model objects, but occasionally a direct reference to the array
is desired.
</p>
<p id="Collection-Underscore-Methods">
<b class="header">Underscore Methods (24)</b>
<br />
Backbone proxies to <b>Underscore.js</b> to provide 24 iteration functions
on <b>Backbone.Collection</b>. They aren't all documented here, but
you can take a look at the Underscore documentation for the full details&hellip;
</p>
<ul>
<li><a href="http://documentcloud.github.com/underscore/#each">forEach (each)</a></li>
<li><a href="http://documentcloud.github.com/underscore/#map">map</a></li>
<li><a href="http://documentcloud.github.com/underscore/#reduce">reduce (foldl, inject)</a></li>
<li><a href="http://documentcloud.github.com/underscore/#reduceRight">reduceRight (foldr)</a></li>
<li><a href="http://documentcloud.github.com/underscore/#detect">find (detect)</a></li>
<li><a href="http://documentcloud.github.com/underscore/#select">filter (select)</a></li>
<li><a href="http://documentcloud.github.com/underscore/#reject">reject</a></li>
<li><a href="http://documentcloud.github.com/underscore/#all">every (all)</a></li>
<li><a href="http://documentcloud.github.com/underscore/#any">some (any)</a></li>
<li><a href="http://documentcloud.github.com/underscore/#include">include</a></li>
<li><a href="http://documentcloud.github.com/underscore/#invoke">invoke</a></li>
<li><a href="http://documentcloud.github.com/underscore/#max">max</a></li>
<li><a href="http://documentcloud.github.com/underscore/#min">min</a></li>
<li><a href="http://documentcloud.github.com/underscore/#sortBy">sortBy</a></li>
<li><a href="http://documentcloud.github.com/underscore/#sortedIndex">sortedIndex</a></li>
<li><a href="http://documentcloud.github.com/underscore/#toArray">toArray</a></li>
<li><a href="http://documentcloud.github.com/underscore/#size">size</a></li>
<li><a href="http://documentcloud.github.com/underscore/#first">first</a></li>
<li><a href="http://documentcloud.github.com/underscore/#rest">rest</a></li>
<li><a href="http://documentcloud.github.com/underscore/#last">last</a></li>
<li><a href="http://documentcloud.github.com/underscore/#without">without</a></li>
<li><a href="http://documentcloud.github.com/underscore/#indexOf">indexOf</a></li>
<li><a href="http://documentcloud.github.com/underscore/#lastIndexOf">lastIndexOf</a></li>
<li><a href="http://documentcloud.github.com/underscore/#isEmpty">isEmpty</a></li>
</ul>
<pre>
Books.each(function(book) {
book.publish();
});
var titles = Books.map(function(book) {
return book.get("title");
});
var publishedBooks = Books.filter(function(book) {
return book.get("published") === true;
});
var alphabetical = Books.sortBy(function(book) {
return book.author.get("name").toLowerCase();
});
</pre>
<p id="Collection-add">
<b class="header">add</b><code>collection.add(models, [options])</code>
<br />
Add a model (or an array of models) to the collection. Fires an <tt>"add"</tt>
event, which you can pass <tt>{silent: true}</tt> to suppress. If a
<a href="#Collection-model">model</a> property is defined, you may also pass
raw attributes objects.
</p>
<pre class="runnable">
var ships = new Backbone.Collection;
ships.bind("add", function(ship) {
alert("Ahoy " + ship.get("name") + "!");
});
ships.add([
{name: "Flying Dutchman"},
{name: "Black Pearl"}
]);
</pre>
<p id="Collection-remove">
<b class="header">remove</b><code>collection.remove(models, [options])</code>
<br />
Remove a model (or an array of models) from the collection. Fires a
<tt>"remove"</tt> event, which you can use <tt>silent</tt>
to suppress.
</p>
<p id="Collection-get">
<b class="header">get</b><code>collection.get(id)</code>
<br />
Get a model from a collection, specified by <b>id</b>.
</p>
<pre>
var book = Library.get(110);
</pre>
<p id="Collection-getByCid">
<b class="header">getByCid</b><code>collection.getByCid(cid)</code>
<br />
Get a model from a collection, specified by client id. The client id
is the <tt>.cid</tt> property of the model, automatically assigned whenever
a model is created. Useful for models which have not yet been saved to
the server, and do not yet have true ids.
</p>
<p id="Collection-at">
<b class="header">at</b><code>collection.at(index)</code>
<br />
Get a model from a collection, specified by index. Useful if your collection
is sorted, and if your collection isn't sorted, <b>at</b> will still
retrieve models in insertion order.
</p>
<p id="Collection-length">
<b class="header">length</b><code>collection.length</code>
<br />
Like an array, a Collection maintains a <tt>length</tt> property, counting
the number of models it contains.
</p>
<p id="Collection-comparator">
<b class="header">comparator</b><code>collection.comparator</code>
<br />
By default there is no <b>comparator</b> function on a collection.
If you define a comparator, it will be used to maintain
the collection in sorted order. This means that as models are added,
they are inserted at the correct index in <tt>collection.models</tt>.
Comparator functions take a model and return a numeric or string value
by which the model should be ordered relative to others.
</p>
<p>
Note how even though all of the chapters in this example are added backwards,
they come out in the proper order:
</p>
<pre class="runnable">
var Chapter = Backbone.Model;
var chapters = new Backbone.Collection;
chapters.comparator = function(chapter) {
return chapter.get("page");
};
chapters.add(new Chapter({page: 9, title: "The End"}));
chapters.add(new Chapter({page: 5, title: "The Middle"}));
chapters.add(new Chapter({page: 1, title: "The Beginning"}));
alert(chapters.pluck('title'));
</pre>
<p>
<i>
Brief aside: This comparator function is different than JavaScript's regular
"sort", which must return </i><tt>0</tt>, <tt>1</tt>, or <tt>-1</tt>,<i>
and is more similar to a </i><tt>sortBy</tt><i> &mdash; a much nicer API.
</i>
</p>
<p id="Collection-sort">
<b class="header">sort</b><code>collection.sort([options])</code>
<br />
Force a collection to re-sort itself. You don't need to call this under
normal circumstances, as a collection with a <a href="#Collection-comparator">comparator</a> function
will maintain itself in proper sort order at all times. Calling <b>sort</b>
triggers the collection's <tt>"refresh"</tt> event, unless silenced by passing
<tt>{silent: true}</tt>
</p>
<p id="Collection-pluck">
<b class="header">pluck</b><code>collection.pluck(attribute)</code>
<br />
Pluck an attribute from each model in the collection. Equivalent to calling
<tt>map</tt>, and returning a single attribute from the iterator.
</p>
<pre class="runnable">
var stooges = new Backbone.Collection([
new Backbone.Model({name: "Curly"}),
new Backbone.Model({name: "Larry"}),
new Backbone.Model({name: "Moe"})
]);
var names = stooges.pluck("name");
alert(JSON.stringify(names));
</pre>
<p id="Collection-url">
<b class="header">url</b><code>collection.url or collection.url()</code>
<br />
Set the <b>url</b> property (or function) on a collection to reference
its location on the server. Models within the collection will use <b>url</b>
to construct URLs of their own.
</p>
<pre>
var Notes = Backbone.Collection.extend({
url: '/notes'
});
// Or, something more sophisticated:
var Notes = Backbone.Collection.extend({
url: function() {
return this.document.url() + '/notes';
}
});
</pre>
<p id="Collection-fetch">
<b class="header">fetch</b><code>collection.fetch([options])</code>
<br />
Fetch the default set of models for this collection from the server,
refreshing the collection when they arrive. The <b>options</b> hash takes
<tt>success</tt> and <tt>error</tt>
callbacks which will be passed <tt>(collection, response)</tt> as arguments.
When the model data returns from the server, the collection will
<a href="#Collection-refresh">refresh</a>.
Delegates to <a href="#Sync">Backbone.sync</a>
under the covers, for custom persistence strategies.
</p>
<p>
The server handler for <b>fetch</b> requests should return a JSON list of
models, namespaced under "models": <tt>{"models": [...]}</tt> &mdash;
instead of returning the
array directly, we ask you to namespace your models like this by default,
so that it's possible to send down out-of-band information
for things like pagination or error states.
</p>
<pre class="runnable">
Backbone.sync = function(method, model) {
alert(method + ": " + model.url);
};
var Accounts = new Backbone.Collection;
Accounts.url = '/accounts';
Accounts.fetch();
</pre>
<p>
Note that <b>fetch</b> should not be used to populate collections on
page load &mdash; all models needed at load time should already be
bootstrapped in to place. <b>fetch</b> is intended for lazily-loading models
for interfaces that are not needed immediately: for example, documents
with collections of notes that may be toggled open and closed.
</p>
<p id="Collection-refresh">
<b class="header">refresh</b><code>collection.refresh(models, [options])</code>
<br />
Adding and removing models one at a time is all well and good, but sometimes
you have so many models to change that you'd rather just update the collection
in bulk. Use <b>refresh</b> to replace a collection with a new list
of models (or attribute hashes), triggering a single <tt>"refresh"</tt> event
at the end. Pass <tt>{silent: true}</tt> to suppress the <tt>"refresh"</tt> event.
</p>
<p>
Here's an example using <b>refresh</b> to bootstrap a collection during initial page load,
in a Rails application.
</p>
<pre>
&lt;script&gt;
Accounts.refresh(&lt;%= @accounts.to_json %&gt;);
&lt;/script&gt;
</pre>
<p id="Collection-create">
<b class="header">create</b><code>collection.create(attributes, [options])</code>
<br />
Convenience to create a new instance of a model within a collection.
Equivalent to instantiating a model with a hash of attributes,
saving the model to the server, and adding the model to the set after being
successfully created. Returns
the model, or <tt>false</tt> if a validation error prevented the
model from being created. In order for this to work, your should set the
<a href="#Collection-model">model</a> property of the collection.
</p>
<pre>
var Library = Backbone.Collection.extend({
model: Book
});
var NYPL = new Library;
var othello = NYPL.create({
title: "Othello",
author: "William Shakespeare"
});
</pre>
<h2 id="Sync">Backbone.sync</h2>
<p>
<b>Backbone.sync</b> is the function the Backbone calls every time it
attempts to read or save a model to the server. By default, it uses
<tt>jQuery.ajax</tt> to make a RESTful JSON request. You can override
it in order to use a different persistence strategy, such as WebSockets,
XML transport, or Local Storage.
</p>
<p>
The method signature of <b>Backbone.sync</b> is <tt>sync(method, model, success, error)</tt>
</p>
<ul>
<li><b>method</b> – the CRUD method (<tt>"create"</tt>, <tt>"read"</tt>, <tt>"update"</tt>, or <tt>"delete"</tt>)</li>
<li><b>model</b> – the model to be saved (or collection to be read)</li>
<li><b>success({model: ...})</b> – a callback that should be fired if the request works</li>
<li><b>error({model: ...})</b> – a callback that should be fired if the request fails</li>
</ul>
<p>
When formulating server responses for <b>Backbone.sync</b> requests,
model attributes will be sent up, serialized as JSON, under the <tt>model</tt>
parameter. When returning a JSON response, send down the model's representation
under the <tt>model</tt> key, and other keys can be used for additional out-of-band
information. When responding to a <tt>"read"</tt> request from a collection,
send down the array of model attribute hashes under the <tt>models</tt> key.
</p>
<p>
The default <b>sync</b> handler maps CRUD to REST like so:
</p>
<ul>
<li><b>create &rarr; POST &nbsp; </b><tt>/collection</tt></li>
<li><b>read &rarr; GET &nbsp; </b><tt>/collection[/id]</tt></li>
<li><b>update &rarr; PUT &nbsp; </b><tt>/collection/id</tt></li>
<li><b>delete &rarr; DELETE &nbsp; </b><tt>/collection/id</tt></li>
</ul>
<p>
If your web server makes it difficult to work with real <tt>PUT</tt> and
<tt>DELETE</tt> requests, you may choose to emulate them instead, using
HTTP <tt>POST</tt>, and passing them under the <tt>_method</tt> parameter
instead, by turning on <tt>Backbone.emulateHttp</tt>:
</p>
<pre>
Backbone.emulateHttp = true;
model.save(); // Sends a POST to "/collection/id", with "_method=PUT"
</pre>
<p>
As an example, a Rails handler responding to an <tt>"update"</tt> call from
<b>Backbone.sync</b> might look like this: <i>(In real code, never use
</i><tt>update_attributes</tt><i> blindly, and always whitelist the attributes
you allow to be changed.)</i>
</p>
<pre>
def update
account = Account.find(params[:id])
account.update_attributes JSON.parse params[:model]
render :json => {:model => account}
end
</pre>
<h2 id="View">Backbone.View</h2>
<p>
Backbone views are almost more convention than they are code &mdash; they
don't determine anything about your HTML or CSS for you, and can be used
with any JavaScript templating library.
The general idea is to organize your interface into logical views,
backed by models, each of which can be updated independently when the
model changes, without having to redraw the page. Instead of digging into
a JSON object, looking up an element in the DOM, and updating the HTML by hand,
you can bind your view's <tt>render</tt> function to the model's <tt>"change"</tt>
event &mdash; and now everywhere that
model data is displayed in the UI, it is always immediately up to date.
</p>
<p id="View-extend">
<b class="header">extend</b><code>Backbone.View.extend(properties, [classProperties])</code>
<br />
Get started with views by creating a custom view class. You'll want to
override the <a href="#View-render">render</a> function, specify your
declarative <a href="#View-handleEvents">events</a>, and perhaps the
<tt>tagName</tt>, <tt>className</tt>, or <tt>id</tt> of the View's root
element.
</p>
<pre>
var DocumentRow = Backbone.View.extend({
tagName: "li",
className: "document-row",
events: {
"click .icon": "open",
"click .button.edit": "openEditDialog",
"click .button.delete": "destroy"
},
initialize: function() {
_.bindAll(this, "render");
},
render: function() {
...
}
});
</pre>
<p id="View-constructor">
<b class="header">constructor / initialize</b><code>new View([options])</code>
<br />
When creating a new View, the options you pass are attached to the view
as <tt>this.options</tt>, for future reference. There are several special
options that, if passed, will be attached directly to the view:
<tt>model</tt>, <tt>collection</tt>,
<tt>el</tt>, <tt>id</tt>, <tt>className</tt>, and <tt>tagName</tt>.
If the view defines an <b>initialize</b> function, it will be called when
the view is first created. If you'd like to create a view that references
an element <i>already</i> in the DOM, pass in the element as an option:
<tt>new View({el: existingElement})</tt>
</p>
<pre>
var doc = Documents.first();
new DocumentRow({
model: doc,
id: "document-row-" + doc.id
});
</pre>
<p id="View-el">
<b class="header">el</b><code>view.el</code>
<br />
All views have a DOM element at all times (the <b>el</b> property),
whether they've already been inserted into the page or not. In this
fashion, views can be rendered at any time, and inserted into the DOM all
at once, in order to get high-performance UI rendering with as few
reflows and repaints as possible.
</p>
<p>
<tt>this.el</tt> is created from the view's <tt>tagName</tt>, <tt>className</tt>,
and <tt>id</tt> properties, if specified. If not, <b>el</b> is an empty <tt>div</tt>.
</p>
<p id="View-jQuery">
<b class="header">$ (jQuery)</b><code>view.$(selector)</code>
<br />
If jQuery is included on the page, each view has a <b>$</b> or <b>jQuery</b>
function that runs queries scoped within the view's element. If you use this
scoped jQuery function, you don't have to use model ids as part of your query
to pull out specific elements in a list, and can rely much more on HTML class
attributes. It's equivalent to running: <tt>$(selector, this.el)</tt>
</p>
<pre>
ui.Chapter = Backbone.View.extend({
serialize : function() {
return {
title: this.$(".title").text(),
start: this.$(".start-page").text(),
end: this.$(".end-page").text()
};
}
});
</pre>
<p id="View-render">
<b class="header">render</b><code>view.render()</code>
<br />
The default implementation of <b>render</b> is a no-op. Override this
function with your code that renders the view template from model data,
and updates <tt>this.el</tt> with the new HTML. A good
convention is to <tt>return this</tt> at the end of <b>render</b> to
enable chained calls.
</p>
<pre>
var Bookmark = Backbone.View.extend({
render: function() {
$(this.el).html(this.template(this.model.toJSON()));
return this;
}
});
</pre>
<p>
Backbone is agnostic with respect to your preferred method of HTML templating.
Your <b>render</b> function could even munge together an HTML string, or use
<tt>document.createElement</tt> to generate a DOM tree. However, we suggest
choosing a nice JavaScript templating library.
<a href="http://github.com/janl/mustache.js">Mustache.js</a>,
<a href="http://github.com/creationix/haml-js">Haml-js</a>, and
<a href="http://github.com/sstephenson/eco">Eco</a> are all fine alternatives.
Because <a href="http://documentcloud.github.com/underscore/">Underscore.js</a> is already on the page,
<a href="http://documentcloud.github.com/underscore/#template">_.template</a>
is available, and is an excellent choice if you've already XSS-sanitized
your interpolated data.
</p>
<p>
Whatever templating strategy you end up with, it's nice if you <i>never</i>
have to put strings of HTML in your JavaScript. At DocumentCloud, we
use <a href="http://documentcloud.github.com/jammit/">Jammit</a> in order
to package up JavaScript templates stored in <tt>/app/views</tt> as part
of our main <tt>core.js</tt> asset package.
</p>
<p id="View-make">
<b class="header">make</b><code>view.make(tagName, [attributes], [content])</code>
<br />
Convenience function for creating a DOM element of the given type (<b>tagName</b>),
with optional attributes and HTML content. Used internally to create the
initial <tt>view.el</tt>.
</p>
<pre class="runnable">
var view = new Backbone.View;
var el = view.make("b", {className: "bold"}, "Bold! ");
$("#make-demo").append(el);
</pre>
<div id="make-demo"></div>
<p id="View-handleEvents">
<b class="header">handleEvents</b><code>handleEvents([events])</code>
<br />
Uses jQuery's <tt>delegate</tt> function to provide declarative callbacks
for DOM events within a view.
If an <b>events</b> hash is not passed directly, uses <tt>this.events</tt>
as the source. Events are written in the format <tt>{"event selector": "callback"}</tt>.
Omitting the <tt>selector</tt> causes the event to be bound to the view's
root element (<tt>this.el</tt>).
</p>
<p>
Using <b>handleEvents</b> provides a number of advantages over manually
using jQuery to bind events to child elements during <a href="#View-render">render</a>. All attached
callbacks are bound to the view before being handed off to jQuery, so when
the callbacks are invoked, <tt>this</tt> continues to refer to the view object. When
<b>handleEvents</b> is run again, perhaps with a different <tt>events</tt>
hash, all callbacks are removed and delegated afresh &mdash; useful for
views which need to behave differently when in different modes.
</p>
<p>
A view that displays a document in a search result might look
something like this:
</p>
<pre>
var DocumentView = Backbone.View.extend({
events: {
"dblclick" : "open",
"click .icon.doc" : "select",
"contextmenu .icon.doc" : "showMenu",
"click .show_notes" : "toggleNotes",
"click .title .lock" : "editAccessLevel",
"mouseover .title .date" : "showTooltip"
},
render: function() {
$(this.el).html(this.template(this.model.toJSON()));
this.handleEvents();
return this;
},
open: function() {
window.open(this.model.get("viewer_url"));
},
select: function() {
this.model.set({selected: true});
},
...
});
</pre>
<h2 id="changelog">Change Log</h2>
<p>
<b class="header">0.1.2</b> &mdash; <small><i>Oct 19, 2010</i></small><br />
Added a <a href="#Model-fetch">Model#fetch</a> method for refreshing the
attributes of single model from the server.
An <tt>error</tt> callback may now be passed to <tt>set</tt> and <tt>save</tt>
as an option, which will be invoked if validation fails, overriding the
<tt>"error"</tt> event.
You can now tell backbone to use the <tt>_method</tt> hack instead of HTTP
methods by setting <tt>Backbone.emulateHttp = true</tt>.
Existing Model and Collection data is no longer sent up unnecessarily with
<tt>GET</tt> and <tt>DELETE</tt> requests. Added a <tt>rake lint</tt> task.
Backbone is now published as an <a href="http://npmjs.org">NPM</a> module.
</p>
<p>
<b class="header">0.1.1</b> &mdash; <small><i>Oct 14, 2010</i></small><br />
Added a convention for <tt>initialize</tt> functions to be called
upon instance construction, if defined. Documentation tweaks.
</p>
<p>
<b class="header">0.1.0</b> &mdash; <small><i>Oct 13, 2010</i></small><br />
Initial Backbone release.
</p>
<p>
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