undefined method `context_class` with new versions of sass/sprockets

[Frexuz]

Error

/home/frexuz/.rbenv/versions/2.2.0/lib/ruby/gems/2.2.0/gems/polymer-rails-1.1.0/lib/polymer-rails/
railtie.rb:7:in `block in <class:Railtie>': undefined method `context_class' for nil:NilClass (NoMethodError)

Gemfile

source 'http://rubygems.org'
source 'http://gems.github.com/'

gem 'rails', '4.2.4'
gem 'polymer-rails'

#truncated...

group :assets do
  gem 'sass', '3.4.18'
  gem 'sass-rails', '~> 5.0.4'
  gem 'sprockets', '3.3.4'
  gem 'sprockets-rails', '3.0.0.beta2', :require => 'sprockets/railtie'
end

What's going on? :/

[alchaplinsky]

For some reason Rails.application.assets is nil in your app. Can you investigate that?

[alchaplinsky]

@Frexuz is this still an issue for you?

[Frexuz]

Sorry, I haven't been able to investigate further. I will let you know when I do :) @alchapone

[Frexuz]

Not sure how I'm supposed to debug further. I added config.assets.enabled = true in application.rb.

NoMethodError: undefined method `context_class' for nil:NilClass
/var/www/episodecalendar.com/config/environment.rb:2:in `<top (required)>'

initializers/assets.rb

Rails.application.config.assets.version = '1.0'

development.rb

Rails.application.configure do
  config.cache_classes = false
  config.eager_load = false
  config.consider_all_requests_local       = true
  config.action_controller.perform_caching = false
  config.action_controller.perform_caching = true
  config.action_mailer.raise_delivery_errors = false
  config.active_support.deprecation = :log
  config.active_record.migration_error = :page_load
  config.assets.debug = false
  config.action_mailer.default_url_options = { :host => "localhost" }
  config.assets.raise_runtime_errors = true
  config.action_view.raise_on_missing_translations = true
end

environment.rb

require File.expand_path('../application', __FILE__)
Rails.application.initialize!

application.rb

require File.expand_path('../boot', __FILE__)

require 'rails/all'
require 'csv'

Bundler.require(:default, Rails.env)

module Episodecalendar2
  class Application < Rails::Application
    config.autoload_paths += %W(#{Rails.root}/app/sweepers #{Rails.root}/lib)
    config.autoload_paths += Dir[ Rails.root.join('app', 'concerns', '**/') ]
    config.encoding = "utf-8"
    config.i18n.available_locales = ['en', 'br', 'de', 'es', 'fr', 'it', 'pl', 'pt', 'tr']
    config.i18n.fallbacks = true
    config.i18n.fallbacks = { 'br': 'pt_BR' }
    config.filter_parameters += [:password]
    config.to_prepare do
      Devise::Mailer.layout "email"
    end
    config.assets.enabled = true
    config.active_record.raise_in_transactional_callbacks = true
  end
end

gemfile (removed anything not related to assets, and the gemfile.lock, and ran bundle install again)

source 'http://rubygems.org'
source 'http://gems.github.com/'

#Main
gem 'rails', '4.2.3'
gem 'therubyracer', require: 'v8'
gem 'jquery_mobile_rails'
gem 'polymer-rails'

group :assets do
  gem 'sass', '3.4.19'
  gem 'sass-rails', '5.0.4'
  gem 'sprockets', '3.4.0'
  gem 'sprockets-rails', '3.0.0.beta2', :require => 'sprockets/railtie'
  gem 'uglifier', '>= 1.3.0'
end

Have i missed something in the configurations?

[Frexuz]

Also just tried a completely new rails project (4.2.3)

ONLY thing I've changed is adding the gems to the Gemfile:

gem 'polymer-rails'

group :assets do
  gem 'sass', '3.4.19'
  gem 'sass-rails', '5.0.4'
  gem 'sprockets', '3.4.0'
  gem 'sprockets-rails', '3.0.0.beta2', :require => 'sprockets/railtie'
end

rake assets:precompile RAILS_ENV="production" runs fine without polymer-rails, as soon as I add it, I get the error.

.... also tried config.assets.css_compressor = :sass

[agnewtj]

Getting the same error. The breakage seems to have been introduced with release 1.1.0. If I downgrade to 1.0.8, it works.

[scarhand]

This seems to be related to sprockets-rails 3.x as well. After I downgraded sprockets-rails to v2.3.3 the assets compiled successfully. Upgrading sprockets-rails to v3 breaks the compilation of assets.

See also the comment at https://github.com/rails/sprockets-rails - config.assets.compile "Enables Sprockets compile environment. If disabled, Rails.application.assets will be nil to prevent inadvertent compilation calls. View helpers will depend on assets being precompiled to public/assets in order to link to them. Initializers expecting Rails.application.assets during boot should be accessing the environment in a config.assets.configure block. See below."

[voondo]

Same error with sprockets-rails 3.x (works fine with 2.x)

[tden012]

I ran into the same issue - and after some searching, found a probable fix...

I'm kind of new to git, so I don't know how to do a pull request or what's involved - so I'll post what I've found here.

This is the link that gave me the idea for the solution:

https://github.com/reactjs/react-rails/commit/a3d0dad530ab4335ba0c66cf92d5d5ec6c007710

I believe that the problem may be solved if following code in /lib/polymer-rails/railtie.rb:

initializer :polymer_html_import do
  helpers = %q{ include AssetTagHelper }
  ::ActionView::Base.module_eval(helpers)
  ::Rails.application.assets.context_class.class_eval(helpers)
end

is changed to this:

initializer :polymer_html_import do |app|
  helpers = %q{ include AssetTagHelper }
  ::ActionView::Base.module_eval(helpers)
  app.config.assets.context_class.class_eval(helpers)
end

I'm not quite sure the mechanism that this works by - but it seems that other gem developers have gone down this path.

[TastyCatFood]

I got the same error. shifted ::Rails.application.assets.context_class.class_eval(helpers) to config.after_initialize. app.assets pointed to nil, so I tried: Sprockets.register_preprocessor 'text/html', Polymer::Rails::DirectiveProcessor Sprockets.register_bundle_processor 'text/html', ::Sprockets::Bundle app.config.assets.register_postprocessor 'text/html', Polymer::Rails::ComponentsProcessorV3 Now I believe it's running. I'm trying to run dart-polymer, so I have a few more troubles to deal with though.

module Polymer
module Rails
class Railtie < ::Rails::Railtie
config.after_initialize do|app|
helpers = %q{ include AssetTagHelper }
::ActionView::Base.module_eval(helpers)
::Rails.application.assets.context_class.class_eval(helpers)
end

  initializer :precompile_polymer do |app|
    if app.config.respond_to? (:assets)
      app.config.assets.precompile += %w( polymer/polymer.js )
    end
  end

  initializer :add_preprocessors do |app|
    if Polymer::Rails::LEGACY_SPROCKETS
      add_preprocessors_legacy(app)
    else
      add_preprocessors(app)
    end
  end

  private

  def add_preprocessors(app)
    Sprockets.register_mime_type 'text/html', extensions: ['.html']
    Sprockets.register_preprocessor 'text/html', Polymer::Rails::DirectiveProcessor
    Sprockets.register_bundle_processor 'text/html', ::Sprockets::Bundle
    app.config.assets.register_postprocessor 'text/html', Polymer::Rails::ComponentsProcessorV3
  end

  def add_preprocessors_legacy(app)
    app.assets.register_mime_type "text/html", '.html'
    app.assets.register_preprocessor "text/html", Polymer::Rails::DirectiveProcessor
    app.assets.register_postprocessor 'text/html', :web do |context, data|
      Polymer::Rails::ComponentsProcessorV2.new(context, data).process
    end
  end

end
end
end

[rafalee]

Having the same issue, I'm using

gem 'rails', '4.2.4' gem 'polymer-rails', '1.2.2'

anyone figure it out a solution?

[hankish]

@rafalee: I'm running rails 4.2.5 and was getting this issue too. When I updated my gemfile to:

gem 'rails', '4.2.5'
gem 'polymer-rails', '1.0.8'

and then ran a full bundle update it resolved the issue (and downgraded my sprockets gem version from 3.5.2 to 2.12.4). if that doesn't work for you maybe add the line gem 'sprockets', '2.12.4'?

[LuisHCK]

@hankish I followed your instructions and works correctly! :+1:

[tostasqb]

Leaving my solution here. In the gem file I removed sprockets gem, leaving only sprockets-rails and with this order.

gem 'sass-rails', '~> 5.0'
gem 'sprockets-rails'

On config/assets updated context_class lines to

config.assets.configure do |env|
  env.context_class.class_eval do
    # in my case I included....
    include Rails.application.routes.url_helpers
    include ActionView::Helpers
  end
end

[Odaeus]

In case it's useful, I've implemented a fix that I'm still testing, but it works so far for me: https://github.com/Odaeus/polymer-rails/commit/dca1467475875d9418f618b6ebe20aec74737198 I just moved most of it to config.after_initialize because Sprockets isn't ready until then.

Update: turns out my solution didn't work due to test/production environments receiving an immutable version of the Sprockets environment by that point! I have an even better :smile: fix now https://github.com/Odaeus/polymer-rails/commit/225f196026a315e2956c5d0403f3f31c8f10a95d that seems to be the Correct Way:tm:.

Update 2: happy to make a PR with backwards compatibility, though it's a pretty trivial change.

[alchaplinsky]

@Frexuz Try using latest version of polymer-rails. It should now support sprockets v3.x

[hankish]

This issue has been completely resolved for me and I'm pretty sure it can be closed.