Cannot access "current_user" from ApplicationController (< ActionController::Base) but can access from other controllers

Question

This is a really weird error for me, and I've already scoured Google but cannot find anyone with a similar problem. Any help or suggestions would be appreciated!

Started a new Ruby/Rails project recently, using the same stack as a previous, recent, working project. I can access the current_user and its family of helpers from every class that extends ApplicationController, but cannot access any such method from ApplicationController < ActionController::Base, wherein I try to alias that method under another name (see below). The error given is also below.

application_controller.rb

class ApplicationController < ActionController::Base
  protect_from_forgery

  alias_method :old_current_user, :current_user
  helper_method :current_or_guest_user

  def current_or_guest_user
    if current_user
      if session[:guest_user_id]
        logging_in
        guest_user.destroy
        session[:guest_user_id] = nil
      end
      current_user
    else
      guest_user
    end
  end
end

Stack Trace

/Users/shaneckamar/Documents/Development/afraidtotrade/app/controllers/application_controller.rb:4:in `alias_method': undefined method `current_user' for class `ApplicationController' (NameError)
    from /Users/shaneckamar/Documents/Development/afraidtotrade/app/controllers/application_controller.rb:4:in `<class:ApplicationController>'
    from /Users/shaneckamar/Documents/Development/afraidtotrade/app/controllers/application_controller.rb:1:in `<top (required)>'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activesupport-3.2.13/lib/active_support/dependencies.rb:469:in `load'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activesupport-3.2.13/lib/active_support/dependencies.rb:469:in `block in load_file'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activesupport-3.2.13/lib/active_support/dependencies.rb:639:in `new_constants_in'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activesupport-3.2.13/lib/active_support/dependencies.rb:468:in `load_file'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activesupport-3.2.13/lib/active_support/dependencies.rb:353:in `require_or_load'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activesupport-3.2.13/lib/active_support/dependencies.rb:502:in `load_missing_constant'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activesupport-3.2.13/lib/active_support/dependencies.rb:192:in `block in const_missing'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activesupport-3.2.13/lib/active_support/dependencies.rb:190:in `each'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activesupport-3.2.13/lib/active_support/dependencies.rb:190:in `const_missing'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activesupport-3.2.13/lib/active_support/inflector/methods.rb:230:in `block in constantize'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activesupport-3.2.13/lib/active_support/inflector/methods.rb:229:in `each'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activesupport-3.2.13/lib/active_support/inflector/methods.rb:229:in `constantize'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activesupport-3.2.13/lib/active_support/core_ext/string/inflections.rb:54:in `constantize'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/devise-2.2.4/app/controllers/devise_controller.rb:2:in `<top (required)>'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activesupport-3.2.13/lib/active_support/dependencies.rb:469:in `load'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activesupport-3.2.13/lib/active_support/dependencies.rb:469:in `block in load_file'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activesupport-3.2.13/lib/active_support/dependencies.rb:639:in `new_constants_in'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activesupport-3.2.13/lib/active_support/dependencies.rb:468:in `load_file'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activesupport-3.2.13/lib/active_support/dependencies.rb:353:in `require_or_load'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activesupport-3.2.13/lib/active_support/dependencies.rb:502:in `load_missing_constant'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activesupport-3.2.13/lib/active_support/dependencies.rb:192:in `block in const_missing'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activesupport-3.2.13/lib/active_support/dependencies.rb:190:in `each'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activesupport-3.2.13/lib/active_support/dependencies.rb:190:in `const_missing'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/devise-2.2.4/app/controllers/devise/sessions_controller.rb:1:in `<top (required)>'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activesupport-3.2.13/lib/active_support/dependencies.rb:469:in `load'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activesupport-3.2.13/lib/active_support/dependencies.rb:469:in `block in load_file'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activesupport-3.2.13/lib/active_support/dependencies.rb:639:in `new_constants_in'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activesupport-3.2.13/lib/active_support/dependencies.rb:468:in `load_file'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activesupport-3.2.13/lib/active_support/dependencies.rb:353:in `require_or_load'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activesupport-3.2.13/lib/active_support/dependencies.rb:502:in `load_missing_constant'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activesupport-3.2.13/lib/active_support/dependencies.rb:192:in `block in const_missing'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activesupport-3.2.13/lib/active_support/dependencies.rb:190:in `each'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activesupport-3.2.13/lib/active_support/dependencies.rb:190:in `const_missing'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activeadmin-0.6.0/lib/active_admin/devise.rb:57:in `<module:Devise>'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activeadmin-0.6.0/lib/active_admin/devise.rb:4:in `<module:ActiveAdmin>'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activeadmin-0.6.0/lib/active_admin/devise.rb:3:in `<top (required)>'
    from /Users/shaneckamar/Documents/Development/afraidtotrade/config/routes.rb:2:in `block in <top (required)>'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/actionpack-3.2.13/lib/action_dispatch/routing/route_set.rb:289:in `instance_exec'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/actionpack-3.2.13/lib/action_dispatch/routing/route_set.rb:289:in `eval_block'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/actionpack-3.2.13/lib/action_dispatch/routing/route_set.rb:267:in `draw'
    from /Users/shaneckamar/Documents/Development/afraidtotrade/config/routes.rb:1:in `<top (required)>'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activesupport-3.2.13/lib/active_support/dependencies.rb:245:in `load'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activesupport-3.2.13/lib/active_support/dependencies.rb:245:in `block in load'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activesupport-3.2.13/lib/active_support/dependencies.rb:236:in `load_dependency'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activesupport-3.2.13/lib/active_support/dependencies.rb:245:in `load'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/railties-3.2.13/lib/rails/application/routes_reloader.rb:40:in `block in load_paths'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/railties-3.2.13/lib/rails/application/routes_reloader.rb:40:in `each'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/railties-3.2.13/lib/rails/application/routes_reloader.rb:40:in `load_paths'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/railties-3.2.13/lib/rails/application/routes_reloader.rb:16:in `reload!'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/railties-3.2.13/lib/rails/application.rb:108:in `reload_routes!'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activeadmin-0.6.0/lib/active_admin/reloader.rb:34:in `reload!'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activeadmin-0.6.0/lib/active_admin/reloader.rb:61:in `block in attach!'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activesupport-3.2.13/lib/active_support/callbacks.rb:429:in `_run__1010026444251623978__prepare__3846619713470166991__callbacks'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activesupport-3.2.13/lib/active_support/callbacks.rb:405:in `__run_callback'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activesupport-3.2.13/lib/active_support/callbacks.rb:385:in `_run_prepare_callbacks'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activesupport-3.2.13/lib/active_support/callbacks.rb:81:in `run_callbacks'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/actionpack-3.2.13/lib/action_dispatch/middleware/reloader.rb:74:in `prepare!'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/actionpack-3.2.13/lib/action_dispatch/middleware/reloader.rb:48:in `prepare!'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/railties-3.2.13/lib/rails/application/finisher.rb:47:in `block in <module:Finisher>'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/railties-3.2.13/lib/rails/initializable.rb:30:in `instance_exec'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/railties-3.2.13/lib/rails/initializable.rb:30:in `run'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/railties-3.2.13/lib/rails/initializable.rb:55:in `block in run_initializers'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/railties-3.2.13/lib/rails/initializable.rb:54:in `each'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/railties-3.2.13/lib/rails/initializable.rb:54:in `run_initializers'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/railties-3.2.13/lib/rails/application.rb:136:in `initialize!'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/railties-3.2.13/lib/rails/railtie/configurable.rb:30:in `method_missing'
    from /Users/shaneckamar/Documents/Development/afraidtotrade/config/environment.rb:5:in `<top (required)>'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activesupport-3.2.13/lib/active_support/dependencies.rb:251:in `require'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activesupport-3.2.13/lib/active_support/dependencies.rb:251:in `block in require'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activesupport-3.2.13/lib/active_support/dependencies.rb:236:in `load_dependency'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activesupport-3.2.13/lib/active_support/dependencies.rb:251:in `require'
    from /Users/shaneckamar/Documents/Development/afraidtotrade/config.ru:3:in `block in <main>'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/rack-1.4.5/lib/rack/builder.rb:51:in `instance_eval'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/rack-1.4.5/lib/rack/builder.rb:51:in `initialize'
    from /Users/shaneckamar/Documents/Development/afraidtotrade/config.ru:in `new'
    from /Users/shaneckamar/Documents/Development/afraidtotrade/config.ru:in `<main>'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/rack-1.4.5/lib/rack/builder.rb:40:in `eval'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/rack-1.4.5/lib/rack/builder.rb:40:in `parse_file'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/rack-1.4.5/lib/rack/server.rb:200:in `app'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/railties-3.2.13/lib/rails/commands/server.rb:46:in `app'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/rack-1.4.5/lib/rack/server.rb:304:in `wrapped_app'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/rack-1.4.5/lib/rack/server.rb:254:in `start'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/railties-3.2.13/lib/rails/commands/server.rb:70:in `start'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/railties-3.2.13/lib/rails/commands.rb:55:in `block in <top (required)>'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/railties-3.2.13/lib/rails/commands.rb:50:in `tap'
    from /usr/local/rvm/gems/ruby-1.9.3-p392/gems/railties-3.2.13/lib/rails/commands.rb:50:in `<top (required)>'
    from script/rails:6:in `require'
    from script/rails:6:in `<main>' 

Environment/Project Details

• Old project and new project both use the same gems.
• Running Mac OS X 10.8
• RVM, current ruby/gemset is ruby-1.9.3-p392
• Rails 3.2.1

Remedies Attempted

• Paid great attention matching the versions in the new Gemfile with the versions in the old project's Gemfile.lock.
• Restarted. Several times.
• Reloaded RVM (via $ rvm reload)
• Restarted POW/Anvil
• Tried starting from the console instead of using pow/anvil
• Compared the old, working project to the new one for hours, trying to find differences in configuration or initialization files. There were none.

Gemfile

gem 'rails', '3.2.13'
gem 'pg'


group :assets do


gem 'sass-rails',   '~> 3.2.3'
      gem 'coffee-rails', '~> 3.2.1'
      gem 'less-rails'
      gem 'bourbon'
      gem 'anjlab-bootstrap-rails', :require => 'bootstrap-rails',
          :github => 'anjlab/bootstrap-rails',
          :branch => '3.0.0'
      gem 'therubyracer', :platform => :ruby
      gem 'uglifier', '>= 1.0.3'
end

gem 'jquery-rails', '2.2.1'

group :development do
      gem 'rails-erd'
      gem 'better_errors', '>= 0.2.0'
      gem 'binding_of_caller', '>= 0.6.8', :platform => :ruby
      gem 'pry-rails'
      gem 'pry-remote'
end

gem 'haml'
gem 'haml-rails'
gem 'activeadmin'
gem 'meta_search',    '>= 1.1.0.pre'
gem 'turbolinks'
gem 'devise', '2.2.4'
gem 'omniauth'
gem 'omniauth-facebook'
gem 'omniauth-twitter', :github => 'arunagw/omniauth-twitter'
gem 'oauth2'
gem 'paperclip', '~> 3.0'
gem 'jquery-turbolinks'
gem 'braintree'
gem 'simple_form'

Answer 1

The current_user method appears dynamically in ApplicationController. Check it out So during the initializing ApplicationController class ruby can't find this method. Honestly the initializing process is more complicated. Devise defines current_user helper when routes are loaded but application controller is loaded before. So I see here 2 solutions:

1. Add this line to ApplicationController before aliasing the current_user method:

   Devise::Controllers::Helpers.define_helpers(Devise::Mapping.new(:user, {}))

2. Define current_user method in ApplicationController using default implementation:

   def current_user @current_user ||= (warden.authenticate(scope: :user) || GuestUser.new) end

I personally prefer 2nd variant because the 1st solution loads devise twice. I think this can break something in your controllers. But if you have tests for your current_user method the 2nd solution solves the problem completely even on devise updates.

Answer 2

try this out for aliasing the current_user method.

    alias :old_current_user, :current_user