gst static method

String? gst(
  1. String? value
)

Implementation

static String? gst(String? value) {
  if (value == null || value.isEmpty) return null;

  final regex = RegExp(r'^[0-9]{2}[A-Z]{5}[0-9]{4}[A-Z]{1}[1-9A-Z]{1}Z[0-9A-Z]{1}$');
  if (!regex.hasMatch(value)) {
    return "Invalid GST Number";
  }
  return null;
}