Handlebars Asset not Compiling with ember-rails after Upgrade to Rails 4 - ember.js

Question

I have a Rails app with Ember on the front-end. Today, I upgraded to Rails 4 and the only issue I cannot resolve is that my Handlebars templates are not being compiled or included as an asset (in development mode). I'm not getting any error messages.
I generated a brand new Rails 4 test app and installed Ember and it serves the Handlebars files just fine. All gems in the test app are present in my app. I tried running rake rails:upgrade, and that had no effect. I tried modifying the ember-rails source to output log messages and the messages and execution paths were the same for the test app and my app.
I'm requiring the templates the same way I always did:
require_tree ./templates
I tried using ember-rails 0.11.1 and from Github master, with no luck.
Related gem versions:
* ember-data-source (0.0.5)
* ember-rails (0.11.1 4dc902b)
* ember-source (1.0.0.rc2.0)
* sprockets (2.9.0)
* sprockets-rails (2.0.0.rc3)
* barber (0.4.1)
Templates are all in app/assets/javascripts/templates and all use the extension .handlebars. Although I tried .hbs and .js.hjs too.
From the Chrome console:
Ember.TEMPLATES
Object {}
I am able to manually compile assets from the Rails command line like this:
environment = Sprockets::Environment.new
environment.append_path 'app/assets/javascripts'
a = environment['templates/test.handlebars']
a.to_s => "..compiled template.."
And the engine is registered:
environment.engines
=> {..".handlebars"=>Ember::Handlebars::Template..}
Rails.application.config.assets.paths includes the app/assets/javascripts folder, as it should.
Any help with this would be greatly appreciated, Thanks!

Answer 1

I've narrowed it down to the following block in ember-rail's engine.rb file. For my app, it is sending register_engine on Sprockets, not app.assets. On the fresh Rails 4 test app, it was also doing this. However, in my app when I force the execution to use app.assets, the handlebar templates are compiled.
I believe since my app was upgraded from Rails 3, somewhere some configuration is missing to properly use Sprockets. I'll post more when I know.
initializer "ember_rails.setup", :after => :append_assets_path, :group => :all do |app|
sprockets = if ::Rails::VERSION::MAJOR == 4
Sprockets.respond_to?('register_engine') ? Sprockets : app.assets
else
app.assets
end
sprockets.register_engine '.handlebars', Ember::Handlebars::Template
sprockets.register_engine '.hbs', Ember::Handlebars::Template
sprockets.register_engine '.hjs', Ember::Handlebars::Template
end
UPDATE:
For me,changing the railties order in application.rb was enough to fix the problem. I believe some other engine was clearing the Sprockets config, so by loading the Ember::Rails engine later in the process, I was able to hack a way around that issue.
config.railties_order = [:main_app, :all, Ember::Rails::Engine]