pattern method

FormFieldValidator pattern (Pattern pattern, { String errorText: "Value does not match pattern." })

FormFieldValidator that requires the field's value to match a regex pattern.

Implementation

static FormFieldValidator pattern(
  Pattern pattern, {
  String errorText = "Value does not match pattern.",
}) {
  return (valueCandidate) {
    if (valueCandidate != null && valueCandidate.isNotEmpty) {
      if (!RegExp(pattern).hasMatch(valueCandidate)) return errorText;
    }
    return null;
  };
}