Universal Module - Ensure Service Options Input Field Is Unique

[qvia]

Is it possible to ensure that the data entered by a customer into a certain custom field is unique. Ie. checked against previous stored entries? To give an example, I don't want two customers with the same postal/zip code (this postal/zip code will be an added custom field).

Can this be done through the JSON input rules?

[Tyson]

No, the input rules in the Universal Module couldn't handle this because it would require the use of a custom, user-defined, method to evaluate the uniqueness of a field by querying the database.