module Trackable
  def self.included(target)
    target.class_eval do
      before_save :track_changes

      def track_changes
        self.changes.each do |field, changes|
          self.history.create do |h|
            was, became = changes
            h.field_name = field
            h.was = was
            h.became = became
            h.changed_by = History.user
          end
        end
      end
    end
  end
end