validate method
Validates your form. Returns a list of form errors, or an empty list if there are no errors - in which case isValid will be true. Validation is handled lazily so you'll need to call this function to trigger validation.
Implementation
List<FormError> validate() {
final errors = validator();
if (errors.isNotEmpty) {
_isValid = false;
} else {
_isValid = true;
}
return errors;
}