active_model_initialize.rb

class Person
  include ActiveModel::MassAssignmentSecurity

  attr_accessor :name, :birthday, :handsomeness
  attr_protected :handsomeness

  def initialize(params = {})
    self.attributes = params
  end

  def attributes=(params = {})
    sanitize_for_mass_assignment(params).each do |k, v|
       send("#{k}=", v)
    end
  end
end