Unique class

Asynchronously validates that a value is unique by hitting a backend endpoint.

The default resolver issues GET {endpoint}?{field}={value} and treats a {"unique": true} (or {"available": true}) response body as a pass. Network errors are logged and treated as passes so they never block form submission; the authoritative check still happens on the server.

Future<void> submit() async {
  await Validator.make(data, {
    'slug': [Required(), Unique('/validate/unique', field: 'slug')],
  }).validateAsync();
}

Debounce

Rapid-fire calls (typing into a field with autovalidate) are coalesced via a per-instance debounce window. Only the last call within the window actually reaches the resolver; earlier calls resolve to true (stale) and never record errors. Set debounce to Duration.zero to disable.

Custom Resolver

Override the HTTP call shape with via:

Unique('/validate/unique', field: 'slug').via((endpoint, field, value) async {
  final response = await Http.post(endpoint, data: {field: value});
  return response['unique'] == true;
});