method

helper_method

v2.3.8 - Show latest stable - 1 note - Class: ActionController::Helpers::ClassMethods

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What's this?

helper_method(*methods) public

Declare a controller method as a helper. For example, the following makes the current_user controller method available to the view:

  class ApplicationController < ActionController::Base
    helper_method :current_user, :logged_in?

    def current_user
      @current_user ||= User.find_by_id(session[:user])
    end

     def logged_in?
       current_user != nil
     end
  end

In a view:

 <% if logged_in? -%>Welcome, <%= current_user.name %><% end -%>

Show source

# File actionpack/lib/action_controller/helpers.rb, line 163
      def helper_method(*methods)
        methods.flatten.each do |method|
          master_helper_module.module_eval "def \#{method}(*args, &block)                    # def current_user(*args, &block)\ncontroller.send(%(\#{method}), *args, &block)  #   controller.send(%(current_user), *args, &block)\nend                                             # end\n"
        end
      end

September 18, 2014 - (<= v4.0.2)

0 thanks

Only in ApplicationController

Seems like we can use helper_method only in ApplicationController. Even if we will create child controller, methods that will be created in child and listed in child’s helper_method will not be accessible from the view.

For example, we have

class SystemController < ApplicationController
 def important_method
   "I am important!"
 end
end

and

class BookController < SystemController
 def index
 end
end

And calling important_method from Book’s index view will raise an NoMethodError.

helper_method

Related methods

Only in ApplicationController