Special rules

Emails, URLs, dates, and comparison with another field. All special rules return FORMAT_ERROR for objects and lists.

emailChecks that the value is an email address.'email'WRONG_EMAILurlChecks that the value is a URL. Only the http and https protocols are allowed, and the protocol is required.'url'WRONG_URLiso_dateChecks that the value is an ISO 8601 date without time, for example "2014-08-14".'iso_date'WRONG_DATEiso_datetime2.5Checks that the value is an ISO 8601 date and time with an offset, and returns it in UTC, for example "2026-10-29T08:00:00.000Z".'iso_datetime', { iso_datetime: { min: 'today' } }WRONG_DATETIMEDATETIME_TOO_EARLYDATETIME_TOO_LATEequal_to_fieldChecks that the value is equal to the value of another field, for example a password confirmation. Values are compared as strings: "10" and 10 are equal, while "10" and "1e1" are not. A missing field is not equal to any value.{ equal_to_field: 'password' }FIELDS_NOT_EQUALiso_time2.5Checks that the value is a time of day without a date and an offset: HH:MM, HH:MM:SS, or HH:MM:SS with a fraction of a second.'iso_time', { iso_time: { min: '09:00', max: '18:00' } }WRONG_TIMETIME_TOO_EARLYTIME_TOO_LATE