Robert Mosolgo

To my knowledge, batman.js is not maintained. For that reason, I don't suggest that you use it for a new project!

Slim Templates with Batman.js and the Rails Asset Pipeline

You can use Slim (or Haml) to serve your Batman.js templates in the Rails Asset Pipeline.

1. Include Slim in your gemfile

Add this line to your Gemfile:

```ruby Gemfile gem “slim”

# 2. Register the Slim engine with Rails

Make a new initializer (eg, `config/initializers/slim_assets.rb`) and put this in it:

```ruby config/initializers/slim_assets.rb
Rails.application.assets.register_engine('.slim', Slim::Template)

Credit: Dillon Buchanan

Update: Serving compiled Slim (or Haml) assets in production

When you deploy to production, if you have config.initialize_on_precompile = false, an initializer isn’t going to work. You’ll have to register the Sprockets engine another way. Add it to the application config in config/application.rb:

```ruby config/application.rb module MyApp class Application < Rails::Application # … config stuff … config.before_initialize do |app| require ‘sprockets’ require ‘slim’ # require ‘tilt’ # for Haml Sprockets::Engines #force autoloading Sprockets.register_engine ‘.slim’, Slim::Template # Sprockets.register_engine ‘.haml’, Tilt::HamlTemplate # for Haml end # … more config stuff … end end

Now, you'll have the Slim template engine available even if your app doesn't intialize, which is most notably the case for `bundle exec rake assets:precompile`. Nice!

# 3. Beef up your BatmanController

At time of writing, the `batman-rails`-generated BatmanController won't work right in production. There's an [outstanding PR]( with a fix. If that's closed, then we're good to go. In the mean time, Make your `app/controllers/batman_controller.rb` look like this:

```ruby app/controllers/batman_controller.rb
class BatmanController < ApplicationController
  def index
    if request.xhr?
      prefix_length = Rails.application.config.assets.prefix.length + 1
      path = request.path[prefix_length..-1]
      render :text => Rails.application.assets[path]
      render nothing: true, layout: 'batman'

When this is done, any files ending in .html.slim in assets will be served as rendered HTML in response to XHR (Ajax) requests. Note that all non-XHR requests will still receive the batman layout (but then Batman will respond to the request, so you’re all good).