def user_as_string=(user)
      # reset both either way
      self.user_as_model = self.username = nil
      user.is_a?(::ActiveRecord::Base) ?
        self.user_as_model = user :
        self.username = user
    end
def user_as_string=(user)
      # reset both either way
      self.user_as_model = self.username = nil
      user.is_a?(::ActiveRecord::Base) ?
        self.user_as_model = user :
        self.username = user
    end
Allows user to be set to either a string or an ActiveRecord object
 @private