how modify session in model? - ruby-on-rails-3

Question

I am using Rails 3. I was coding a controller very verbose. So i am trying refactoring the controller.
I coded a class called ProductMaker which make a product and modify session (product task for wizard form as current_step, if the request is a refresh, etc)
This class has method that receiving session as parameter, modify and then return this new session.
Controller action:
def new
#INITIALIZE CODE
session[:refresh] ||= SortedArray.new [1]
#...MORE CODE
end
def create
#...MUCH CODE
unless Utilities.is_refresh(session[:refresh])
#...more code
session = ProductMaker.some_method_which_return_session(session) #KEY PROBLEM LINE
#...more code
end
#... MORE CODE
end
My ProductMaker class in lib folder:
class ProductMaker
def self.some_method_which_return_session(session)
session[:any_key] = "some value"
return session
end
end
However when I write the KEY PROBLEM LINE the session is a nil value. If i comment this line the session is a ActionDispatch::Session::AbstractStore::SessionHash.
Which could be the problem?
How could i refactoring controller logic, that modify many session keys and 'fill' a model depending the session values, to model/class ?
UPDATE:
I am reading about binding in ruby.
How could modify the session using bindings and eval method?
If you have other ideas, please post your answer.
Thanks in advance

Answer 1

You are assigning session = on the "key problem line". This creates a local variable for the create method which shadows the session method on ActionController::Base. The local variable is nil before you assign it (not non-existent!) so the end result is that session == nil for the whole method, which obviously breaks everything. So: don't assign session. Call your return value something else.

Answer 2

I use binding technique. So i pass the context (simulating parameter pass reference variables).
Example
class OwnController < ApplicationController
def my_action
SettingManager.modify("session[:session]", binding)
end
end
class SettingManager
def self.modify(session, binding)
eval "#{session}.any_value = 5" binding
eval "#{session}.other_value = 'value'", binding
end
end

Answer 3

Finally I use bindings.
For example:
class SessionManager
self.update(session, binding)
eval "#{session} = 0", binding
end
end
class SomeController < ApplicationController
def foo_action_1
session[:refresh] = 1
end
def example_ajax_modify_session
a = session[:refresh] == 1 #true
SessionManager.update("session[:refresh]", binding)
b = session[:refresh] == 1 #false
a == b #false because a == 1 and b == 0
end
I had to modify and manage many session values so before I has a very verbose controller.
Now I could refactoring this logic to model.