How to use shared variables in a rails controller?

Question

Ruby on Rails

Hello.
Can you please tell me how to create variables that can be used (read and changed) from any Ruby on Rails controller method? Something like this is needed:

class ExController < ApplicationController
  def common_variable
     @com_var = 1
  end

  def first_action
     puts @com_var
  end 

  def second_action
     @com_var = 2
  end
end

What I expect:

first_action
>> 1
second_action
first_action
>> 2

What is actually happening:

first_action
>> nil
second_action
first_action
>> nil

Answer 1

To store data common to all controller methods, you should use the session mechanism:
guides.rubyonrails.org/action_controller_overview....

Answer 2

@var - class instance variable
@ @var - class variable
$var - global variable

Answer 3

Did you answer your own question?) Specify the question, please)

Answer 4

If you need to save the value of a variable between requests, then cookies or session.
Describe the problem more clearly. I'm sure there is a more elegant solution.