validateOCN static method

String? validateOCN(
  1. String? value
)

Ensures that a user provides an OCN that is 4 characters

Implementation

static String? validateOCN(String? value) {
  if (value == null || value.isEmpty) {
    return 'Value can not be empty';
  }

  final regex = RegExp(r'^[:alnum]{4}$', caseSensitive: false, multiLine: false);
  if (!regex.hasMatch(value)) {
    return 'Value should be a 4 character ID';
  }

  return null;
}