def reset_attribute!(attr)
      attr = database_field_name(attr)
      attributes[attr] = changed_attributes.delete(attr) if attribute_changed?(attr)
    end
def reset_attribute!(attr)
      attr = database_field_name(attr)
      attributes[attr] = changed_attributes.delete(attr) if attribute_changed?(attr)
    end
Set the attribute back to its old value.

 @example Reset the attribute.
   model.reset_attribute!("name")

 @param [ String ] attr The name of the attribute.

 @return [ Object ] The old value.

 @since 2.4.0