    # File lib/active_record/validations.rb, line 54
        def add_on_empty(attributes, custom_message = nil)
          for attr in [attributes].flatten
            value = @base.respond_to?(attr.to_s) ? @base.send(attr.to_s) : @base[attr.to_s]
            is_empty = value.respond_to?(:empty?) ? value.empty? : false
            add(attr, :empty, :default => custom_message) unless !value.nil? && !is_empty
          end
        end