getting "uninitialized constant ApplicationController" in rails application

Question

I am trying to learn Rails 4 framework and followed official doc

I ran these following commands:

rails new fold

It created a new project

rails generate controller home index

It generate a home_controller and views/home/index.html.erb

Content of home_controller :

class HomeController < ApplicationController
 def index
 end
end

For routing I added following code in routes.rb

 get 'home/index' => 'home#index'

After running the application I am getting :

uninitialized constant ApplicationController

What I am doing wrong here? Here is the Stacktrace

app/controllers/home_controller.rb:1:in `<top (required)>'
activesupport (4.2.4) lib/active_support/inflector/methods.rb:261:in `const_get'
activesupport (4.2.4) lib/active_support/inflector/methods.rb:261:in `block in constantize'
activesupport (4.2.4) lib/active_support/inflector/methods.rb:259:in `each'
activesupport (4.2.4) lib/active_support/inflector/methods.rb:259:in `inject'
activesupport (4.2.4) lib/active_support/inflector/methods.rb:259:in `constantize'
actionpack (4.2.4) lib/action_dispatch/routing/route_set.rb:72:in `controller_reference'
actionpack (4.2.4) lib/action_dispatch/routing/route_set.rb:62:in `controller'
actionpack (4.2.4) lib/action_dispatch/routing/route_set.rb:41:in `serve'
actionpack (4.2.4) lib/action_dispatch/journey/router.rb:43:in `block in serve'
actionpack (4.2.4) lib/action_dispatch/journey/router.rb:30:in `each'
actionpack (4.2.4) lib/action_dispatch/journey/router.rb:30:in `serve'
actionpack (4.2.4) lib/action_dispatch/routing/route_set.rb:821:in `call'

What is the wrong with the code?

Answer 1

Do you have an application.rb file? This file should be sitting inside of app/controllers. All of the other controllers inherit from this controller. The most minimal setup would look like this:

class ApplicationController < ActionController::Base
end