userIdValidator static method

String? userIdValidator(
  1. String? value
)

Implementation

static String? userIdValidator(String? value) {
  final userId = (value ?? "").trim();
  if (userId.isEmpty) {
    return "Enter user ID";
  }
  if (userId.length > 64) {
    return "Maximum 64 characters allowed";
  }
  if (!RegExp(r'^[a-zA-Z0-9@._+-]+$').hasMatch(userId)) {
    return "Only letters, numbers, @ . _ + - are allowed";
  }
  return null;
}