Are Unique Values validation
The "Are Unique Values" validation plugin is similar to the "Is Unique" validation plugin, but rather than checking that this individual field is unique in the database, instead it checks whether the combination of this element and one or two other elements is unique. If this combination of values has already been saved in a different row of the database then the validation fails.
- Error message - The error message to show in the form when the validation fails
- Additional comparison element - An optional second element to include in the validation