Opal Rails

Rails bindings for Opal Ruby engine. (Changelog)

Installation

In your Gemfile

gem 'opal-rails'

or when you build your new Rails app:

rails new <app-name> --javascript=opal

Configuration

Add your configuration in config/application.rb with the following contents:

module MyApp
  class Application < Rails::Application
    # These are the available options with their default values

    # Compiler options
    config.opal.method_missing      = true
    config.opal.optimized_operators = true
    config.opal.arity_check         = false
    config.opal.const_missing       = true
    config.opal.dynamic_require_severity = :ignore

    # Enable/disable /opal_specs route
    config.opal.enable_specs = true

    # The path to opal specs from Rails.root
    config.opal.spec_location = 'spec-opal'
  end
end

Usage

Asset Pipeline

You can rename app/assets/javascripts/application.js to application.js.rb. Even if not necessary, it is recommended to change Sprockets' //= require statements to Ruby' require methods. Sprockets' //= require statements won't be known by the opal builder and therefore you can end up adding something twice.

For Opal 0.8 and above, you have to use application.js.rb with the following syntax:

# app/assets/javascripts/application.js.rb

require 'opal'
require 'opal_ujs'
require 'turbolinks'
require_tree '.'

If you want to use application.js, you need to load the Opal modules(files) manually, e.g.:

// application.js
//= require opal
//= require greeter
//= require_self
Opal.load('greeter');

As you see in the example above, Opal also gives you a Ruby equivalent of //= require_tree.

Opal requires are forwarded to the Asset Pipeline at compile time (similarly to what happens for RubyMotion). You can use either the .rb or .opal extension:

# app/assets/javascripts/greeter.js.rb

puts "G'day world!" # check the console!

# Dom manipulation
require 'opal-jquery'

Document.ready? do
  Element.find('body > header').html = '<h1>Hi there!</h1>'
end

As a template

You can use it for your views too, it even inherits instance and local variables from actions:

# app/controllers/posts_controller.rb

def create
  @post = Post.create!(params[:post])
  render type: :js, locals: {comments_html: render_to_string(@post.comments)}
end

Each assign is filtered through JSON so it's reduced to basic types:

# app/views/posts/create.js.opal

post = Element.find('.post')
post.find('.title').html    = @post[:title]
post.find('.body').html     = @post[:body]
post.find('.comments').html = comments_html

As a Haml filter (optional)

Of course you need to require haml-rails separately since its presence is not assumed

-# app/views/posts/show.html.haml

%article.post
  %h1.title= post.title
  .body= post.body

%a#show-comments Display Comments!

.comments(style="display:none;")
  - post.comments.each do |comment|
    .comment= comment.body

:opal
  Document.ready? do
    Element.find('#show-comments').on :click do |click|
      click.prevent_default
      click.current_target.hide
      Element.find('.comments').effect(:fade_in)
    end
  end

RSpec support

Extracted to opal-rspec-rails

Add this line to your Gemfile

gem 'opal-rspec-rails', github: 'opal/opal-rspec-rails'

Minitest support

Upcoming as opal-minitest-rails

Shared templates

As long as the templates are inside the sprockets/opal load path, then you should be able to just require them.

Let's say we have this template app/views/shared/test.haml:

.row
  .col-sm-12
    = @bar

We need to make sure Opal can see and compile that template. So we need to add the path to sprockets:

# config/initializers/opal.rb
Rails.application.config.assets.paths << Rails.root.join('app', 'views', 'shared').to_s

Now, somewhere in application.rb you need to require that template, and you can just run it through Template:

# app/assets/javascripts/application.rb
require 'opal'
require 'opal-haml'
require 'test'

@bar = "hello world"

template = Template['test']
template.render(self)
# =>  '<div class="row"><div class="col-sm-12">hello world</div></div>'

Using Ruby gems from Opal

Just use Opal.use_gem in your asset initializer (in config/initializers).

Example:

Opal.use_gem 'cannonbol'

License

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.

mibamur / opal-rails