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Latest commit 59b84cd Apr 16, 2016 @tricknotes tricknotes Merge pull request #525 from bnd5k/master
Fixes minor typo in README

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ember-rails makes developing an Ember.JS application much easier in Rails 3.1+.

The following functionalities are included in this gem:

  • Pre-compiling of your handlebars templates when building your asset pipeline.
  • Inclusion of development and production copies of Ember, Ember Data and Handlebars.
  • Inclusion of ActiveModel::Serializer for integration with Ember Data.

You can see an example of how to use the gem here. There is also a great tutorial by Dan Gebhardt called "Beginning Ember.js on Rails" which is a great read if you're just starting out with Rails and Ember.js.

Getting started

  • Add the gem to your application Gemfile:
gem 'ember-rails'
# gem 'ember-source' # You can specify the Ember.js version you want to use.(such as '~> 1.13.0')
  • Run bundle install
  • Next, generate the application structure:
$ rails generate ember:bootstrap
  • Restart your server (if it's running)

Building a new project from scratch

Rails supports the ability to build projects from a template source ruby file.

To build an Ember centric Rails project you can simply type the following into your command line:

$ rails new my-app -m

Read more about Rails application templates and take a look at the edge_template.rb source code.


To install the latest builds of ember and ember-data. It should be noted that the examples in the getting started guide have been designed to use the released version of ember:

$ rails generate ember:install

You'll probably need to clear out your cache after doing this with:

$ rake tmp:clear

Also, ember-rails includes some flags for the bootstrap generator:

--ember-path or -d   # custom ember path
--skip-git or -g     # skip git keeps
--javascript-engine  # engine for javascript (js, coffee, em or es6)
--app-name or -n     # custom ember app name

For CoffeeScript support

Add coffee-rails to the Gemfile

gem 'coffee-rails'

Run the bootstrap generator in step 4 with an extra flag instead:

$ rails g ember:bootstrap -g --javascript-engine coffee

For EmberScript support

EmberScript is a dialect of CoffeeScript with extra support for computed properties (which do not have to be explicitly declared), the class / extends syntax, and extra syntax to support observers and mixins.

To get EmberScript support, make sure you have the following in your Gemfile:

gem 'ember_script-rails', :github => 'ghempton/ember-script-rails'

You can now use the flag --javascript-engine=em to specify EmberScript assets in your generators, but all of the generators will default to using an EmberScript variant first.

For ES6 support

Ember.js recommends using ES6 syntax. It is supported by Babel via ember-es6_template.

Run the bootstrap generator with an extra flag:

$ rails g ember:bootstrap --javascript-engine=es6


To use ES6 module in your application, the following configuration is required:

Single Ember Application

This is the case for single Ember application in app/assets/javascripts (not under the subdirectory).


import Application from 'ember-rails/application';

const App = Application.extend({
  // Configure your application.


import Application from 'ember-rails/application'; and Application.extend() is important. It provides customized Ember application to resolve dependencies from ES6 modules instead of Ember.Application.extend().


//= require jquery
//= require ember
//= require ember-data
//= require ember-rails/application
//= require ./my-app
//= require_self

require('my-app'); // Run your Ember.js application

Multiple Ember Application

This is the case for multiple Ember application in your Rails application. (Or your Ember application is placed in sub directories of app/assets/javascripts.)

First, you should configure config.ember.module_prefix to nil. To disable prepending the module prefix to you modules.


config.ember.module_prefix = nil

Second, please specify modulePrefix to your Ember application.


import Application from 'ember-rails/application';
import loadInitializers from 'ember/load-initializers';

const App = Application.extend({
  modulePrefix: 'my-app' // This value should be the same as directory name.

loadInitializers(App, 'my-app');


Last, add your endpoint to where you want to run your Ember application.

require('my-app'); // Run your Ember.js application

Configuration Options

The following options are available for configuration in your application or environment-level config files (config/application.rb, config/environments/development.rb, etc.):

Configuration Option Description
config.ember.variant Determines which Ember variant to use. Valid options: :development, :production. Defaults to :production in production, and :development everywhere else.
config.ember.app_name Specificies a default application name for all generators.
config.ember.ember_path Specifies a default custom root path for all generators.
config.ember.module_prefix Sets module prefix for es6 module. This option is used for only es6 scripts. Default value: ember-app.
config.ember.prefix_files Sets some file names to add config.ember.module_prefix into its file name as es6 module name.
config.ember.prefix_dirs Sets some dir names to add config.ember.module_prefix into its directory name as es6 module name.
config.handlebars.precompile Enables or disables precompilation. Default value: true.
config.handlebars.templates_root Sets the root path (under app/assets/javascripts) for templates to be looked up in. Default value: "templates".
config.handlebars.templates_path_separator The path separator to use for templates. Default value: '/'.
config.handlebars.output_type Configures the style of output (options are :amd and :global). Default value: :global.
config.handlebars.amd_namespace Configures the module prefix for AMD formatted output. Default value: nil.
config.handlebars.ember_template Default which Ember template type to compile. Valid options: 'Handlebars',HTMLBars. Defaults to 'Handlebars' when Ember::VERSION is under 1.10.0, HTMLBars when Ember::VERSION is over 1.10.0.


In a mountable engine, ember-rails will not recognize any configurations. Instead, use command line options.

Enabling Features with Feature Flags

See the guide and check features.json for the version of Ember you're using.

If a feature is set to false, you will need to compile ember from source yourself to include it.

Important note for projects that render JSON responses

ember-rails includes active_model_serializers which affects how ActiveModel and ActiveRecord objects get serialized to JSON, such as when using render json: or respond_with. By default active_model_serializers adds root elements to these responses (such as adding {"posts": [...]} for render json: @posts) which will affect the structure of your JSON responses.

To disable this effect on your JSON responses, put this in an initializer:

# Stop active_model_serializers from adding root elements to JSON responses.
ActiveModel::Serializer.root = false
ActiveModel::ArraySerializer.root = false

See the active_model_serializers documentation for a more complete understanding of other effects this dependency might have on your app.


Ember does not require an organized file structure. However, ember-rails allows you to use rails g ember:bootstrap to create the following directory structure under app/assets/javascripts:

├── adapters
├── components
├── controllers
├── helpers
├── mixins
├── models
├── routes
├── templates
│   └── components
└── views

Additionally, it will add the following lines to app/assets/javascripts/application.js. By default, it uses the Rails Application's name and creates an rails_app_name.js file to set up application namespace and initial requires:

//= require ember
//= require ember-data
//= require_self
//= require rails_app_name
RailsAppName = Ember.Application.create();


$ rails g ember:bootstrap
  insert  app/assets/javascripts/application.js
  create  app/assets/javascripts/models
  create  app/assets/javascripts/models/.gitkeep
  create  app/assets/javascripts/controllers
  create  app/assets/javascripts/controllers/.gitkeep
  create  app/assets/javascripts/views
  create  app/assets/javascripts/views/.gitkeep
  create  app/assets/javascripts/helpers
  create  app/assets/javascripts/helpers/.gitkeep
  create  app/assets/javascripts/components
  create  app/assets/javascripts/components/.gitkeep
  create  app/assets/javascripts/templates
  create  app/assets/javascripts/templates/.gitkeep
  create  app/assets/javascripts/templates/components
  create  app/assets/javascripts/templates/components/.gitkeep
  create  app/assets/javascripts/mixins
  create  app/assets/javascripts/mixins/.gitkeep
  create  app/assets/javascripts/adapters
  create  app/assets/javascripts/adapters/.gitkeep
  create  app/assets/javascripts/app.js

If you want to avoid .gitkeep files, use the skip git option like this: rails g ember:bootstrap -g.

Ask Rails to serve HandlebarsJS and pre-compile templates to Ember by putting each template in a dedicated ".hbs", ".js.hjs" or ".handlebars" file (e.g. app/assets/javascripts/templates/admin_panel.hbs) and including the assets in your layout:

<%= javascript_include_tag "templates/admin_panel" %>

If you want to avoid the templates prefix, set the templates_root option in your application configuration block:

config.handlebars.templates_root = 'ember_templates'

If you store templates in a file like app/assets/javascripts/ember_templates/admin_panel.hbs after setting the above config, it will be made available to Ember as the admin_panel template.

(Note: you must clear the local sprockets cache after modifying templates_root, stored by default in tmp/cache/assets)

Default behavior for ember-rails is to precompile handlebars templates. If you don't want this behavior you can turn it off in your application configuration (or per environment in: config/environments/development.rb) block:

config.handlebars.precompile = false

(Note: you must clear the local sprockets cache if you disable precompilation, stored by default in tmp/cache/assets)

Bundle all templates together thanks to Sprockets, e.g create app/assets/javascripts/templates/all.js with:

//= require_tree .

Now a single line in the layout loads everything:

<%= javascript_include_tag "templates/all" %>

Note about ember components

When necessary, ember-rails adheres to a conventional folder structure. To create an ember component you must define the handlebars file inside the components folder under the templates folder of your project to properly register your handlebars component file.


Given the following folder structure:

├── adapters
├── components
├── controllers
├── helpers
├── mixins
├── models
├── routes
├── templates
│   └── components
│       └── my-component.hbs
└── views

and a my-component.hbs file with the following contents:

<h1>My Component</h1>

It will produce the following handlebars output:

<script type="text/x-handlebars" id="components/my-component">
  <h1>My Component</h1>

You can reference your component inside your other handlebars template files by the handlebars file name:

{{ my-component }}

Specifying Different Versions of Ember/Handlebars/Ember-Data

By default, ember-rails ships with the latest version of Ember, Handlebars, and Ember-Data.

To specify a different version that'll be used for both template precompilation and serving to the browser, you can specify the desired version of one of the above-linked gems in the Gemfile, e.g.:

gem 'ember-source', '~> 1.13.0'

You can also specify versions of 'handlebars-source' and 'ember-data-source', but note that an appropriate 'handlebars-source' will be automatically chosen depending on the version of 'ember-source' that's specified.

You can also override the specific ember.js, handlebars.js, and ember-data.js files that'll be required by the Asset pipeline by placing these files in vendor/assets/ember/development and vendor/assets/ember/production, depending on the config.ember.variant you've specified in your app's configuration, e.g.:

config.ember.variant = :production
# config.ember.variant = :development

Updating Ember

If at any point you need to update Ember.js from any of the release channels, you can do that with

$ rails generate ember:install --channel=<channel>

This will fetch both Ember.js and Ember Data from and copy to the right directory. You can choose between the following channels:

  • canary - This references the 'master' branch and is not recommended for production use.
  • beta - This references the 'beta' branch, and will ultimately become the next stable version. It is not recommended for production use.
  • release - This references the 'stable' branch, and is recommended for production use.

When you don't specify a channel, the release channel is used.

It is also possible to download a specific tagged release. To do this, use the following syntax:

$ rails generate ember:install --tag=v1.13.0 --ember

or for ember-data

$ rails generate ember:install --tag=v1.13.0 --ember-data

CSRF Token

Rails protect_from_forgery requires CSRF token for every XHR except GET. The CSRF token is normally found in app/views/layouts/application.html.* inserted with the rails helper: csrf_meta_tags.

When you use jquery-ujs, the CSRF token will be sent to the rails application on every XHR automatically. If not so, the following JavaScript is required in your code.

$.ajaxPrefilter(function(options, originalOptions, xhr) {
  var token = $('meta[name="csrf-token"]').attr('content');
  xhr.setRequestHeader('X-CSRF-Token', token);

Note on Patches/Pull Requests

  1. Fork the project.
  2. Make your feature addition or bug fix.
  3. Add tests for it. This is important so I don't break it in a future version unintentionally.
  4. Commit, do not mess with rakefile, version, or history. (if you want to have your own version, that is fine but bump version in a commit by itself I can ignore when I pull)
  5. Send me a pull request. Bonus points for topic branches.
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