pattern static method
Implementation
static FormFieldValidator<String> pattern({
required RegExp pattern,
required String message,
bool isRequired = true,
}) =>
(String? value) {
if (isRequired && (value == null || value.isEmpty)) {
return message;
}
if (value != null && value.isNotEmpty && !pattern.hasMatch(value)) {
return message;
}
return null;
};