Where are Rails helpers available?

In Rails 5, all helpers are available for all views and all controllers, and nothing else.

http://api.rubyonrails.org/classes/ActionController/Helpers.html

These helpers are available for all default templates.

By default, each controller will include all helpers.

In views, you can access helpers directly:

module UserHelper
  def fullname(user)
    ...
  end
end

# app/views/items/show.html.erb
...
User: <%= fullname(@user) %>
...

      

        
        
        
      

    

In controllers, you need a method #helpers

to access them:

# app/controllers/items_controller.rb
class ItemsController
  def show
    ...
    @user_fullname = helpers.fullname(@user)
    ...
  end
end

      

        
        
        
      

    

You can still use helper modules in other classes with include

.

# some/other/klass.rb
class Klass
  include UserHelper
end

      

        
        
        
      

    

The old behavior was that all helpers were included in all views, and only every helper was included in the corresponding controller, for example. UserHelper

will only be included in UserController

.

To revert to this behavior, you can set config.action_controller.include_all_helpers = false

to your config/application.rb

file.