Now you can say:

class Song < ActiveRecord::Base

  attr_accessor :virtual_attribute
  
  assignable_values_for :virtual_attribute do
    %w[air fluff]
  end

end

Rails Long Term Support

Rails LTS provides security patches for old versions of Ruby on Rails (2.3, 3.2, 4.2 and 5.2)

assignable_values 0.9.0 supports virtual attributes