Validating a finite state machine (using AASM) on Rails

Question

I'm using AASM by Rubyist to build a 4-step wizard for an AR object. According to the state of the object, there are different validations that need to be done. What is the smartest way to validate an object according to it's state on a certain transition?

Answer 1

Use the :if option, and with_options to bunch 'em together.

class Post < ActiveRecord::Base
  with_options :if => proc {|r| r.signup_step > 2 } do |o|
    o.validates_presence_of :title
    o.validates_presence_of :yeah
  end
end

What exactly you ought to write in the if-proc depends on your implementation, obviously.