gistfile1.rb

class PeopleController < CrudController
  respond_to :js

  def new
    object = build_resource
    object.personable = Individual.new

    super
  end

  protected

  def update_resource(object, resource_params)
    object.localized.assign_attributes(*resource_params)

    if object.valid? && has_personable_and_it_changed?(object)
      object.personable_was.destroy
    end

    super
  end

  def has_personable_and_it_changed?(object)
    object.personable_type_was && object.personable_type_changed?
  end
end