May 28, 2013 – By Tom Dale

Announcement

We have noticed a performance regression, a debug flag was left on by mistake. So if you really want the goodness of RC4 without this regression use this build, we'll have an official release out soon.

Today, we are pleased to announce Ember.js 1.0 RC4:

This RC4 release of Ember puts us very close to the final 1.0 release.

Ember.js 1.0 RC4

As we approach 1.0 final, our focus continues to be on bugfixes, performance, and reliability.

BREAKING CHANGE: Controller/Model Setup

One of the roles of Route objects in an Ember application is to tell controllers which model they should represent.

By default, the object that you return from a route's model hook is set as the model property on the corresponding controller. So, for example, if you have this route:

App.PhotosRoute = Ember.Route.extend({
  model: function() {
    return App.Photo.find();
  }
});

The array returned from model would be set as the model property of the App.PhotosController. This tells the controller that it should present that model to its template.

What if you need to set up additional controllers, beyond the primary controller associated with that route? In that case, you can implement the setupController hook:

App.PhotosRoute = Ember.Route.extend({
  model: function() {
    return App.Photo.find();
  },

  setupController: function(controller, model) {
    this.controllerFor('application').set('showingPhotos', true);
  }
});

This is all well and good, but what if you wanted to prevent a model from being set on the PhotosController at all?

In RC3, preventing this default behavior was impossible. In RC4, implementing the setupController hook prevents the default behavior from happening. This is a potentially breaking change.

If your route implements the setupController hook and you want to preserve default behavior, make sure you call _super() from within the hook:

App.PhotosRoute = Ember.Route.extend({
  model: function() {
    return App.Photo.find();
  },

  setupController: function(controller, model) {
    // Call _super for default behavior
    this._super(controller, model);
    this.controllerFor('application').set('showingPhotos', true);
  }
});

Thanks to Kris Selden and Luke Melia for pulling together PRs from Paul Chavard, Rob Harper and input from others into a cohesive change. We don't take breaking changes lightly at this stage of the release process, but this one is worthwhile.

RSVP 2.0

Ember now embeds version 2.0 of RSVP.js, a microlibrary for Promises/A+ compatible promises.

All of the Ember.js APIs that return promises use this library to ensure compatible behavior.

A big, big thanks to Stefan Penner for all of his work on improving the promises story across both Ember and Ember Data.

Run Loop Extracted to Backburner.js

Erik Bryn has extracted the run loop into the Backburner.js microlibrary, which Ember now uses.

This will allow other frameworks and libraries that use Backburner to benefit from using a deferred event queue, and hopefully we can share our work to make the web platform faster for everyone.

Handlebars RC4 Compatibility

Ember.js RC4 requires the latest release of Handlebars, which is also at RC4.

Improved Route Redirection

Routes provide a redirect hook that allow them to conditionally redirect to a different route. For example, you may redirect the user to a login route if you detect that they do not have an authentication token saved.

Many improvements to the redirect hook have been made to make it more reliable. Additionally, you can now implement this hook in the ApplicationRoute, which previously would not work.

Props to Tom Dale for this work.

ember-testing Improvements

The ember-testing package, included in Ember.js, is the officially-supported library for writing unit and integration tests for Ember apps. Introduced in RC3, this has continued to be improved, with many bug fixes and performance improvements landing in RC4.

A huge thanks to Teddy Zeeny for driving many of these improvements.

disabledWhen {{linkTo}} Option

The {{#linkTo}} Handlebars helper now has a disabledWhen option that can be bound to conditionally disable a link:

{{#linkTo 'upgradeAccount' disabledWhen=isPremiumUser}}
  Upgrade Account
{{/linkTo}}

Thanks to Trek Glowacki for this improvement.