isAccountNumber function

String? isAccountNumber(
  1. String val
)

return an error message if value does not pass the validation validation requires val: not equal null and length must be more or equal to 10 characters

Implementation

String? isAccountNumber(String val) {
  final RegExp reg = RegExp(r"^[0-9]{10}$");
  return reg.hasMatch(val) ? null : "Purse number must be a 10 digit number";
}