unique static method
Check field is unique
Implementation
static Future<bool> unique(
Map<String, dynamic> data,
dynamic value,
String values,
) async {
final resolver = _uniqueValidationResolver;
if (resolver == null) {
throw StateError(
'The unique validation rule requires an ORM/database package to '
'register a unique validation resolver.',
);
}
return resolver(data, value, values);
}