call (DataMapper::Validate::RequiredFieldValidator)

    # File lib/dm-validations/required_field_validator.rb, line 15
          def call(target)
            value = target.validation_property_value(field_name)
            property = target.validation_property(field_name)
            return true if present?(value, property)

            error_message = @options[:message] || default_error(property)
            add_error(target, error_message, field_name)

            false
          end