def add_on_blank(attributes, options = {})
      [attributes].flatten.each do |attribute|
        value = @base.send(:read_attribute_for_validation, attribute)
        add(attribute, :blank, options) if value.blank?
      end
    end
def add_on_blank(attributes, options = {})
      [attributes].flatten.each do |attribute|
        value = @base.send(:read_attribute_for_validation, attribute)
        add(attribute, :blank, options) if value.blank?
      end
    end
Will add an error message to each of the attributes in +attributes+ that is blank (using Object#blank?).