alphanumeric static method

String? alphanumeric(
  1. String? value, {
  2. String? message,
})

Validates alphanumeric characters only

Example:

Validators.alphanumeric('abc123');

Implementation

static String? alphanumeric(String? value, {String? message}) {
  if (value == null || value.isEmpty) return null;
  final regex = RegExp(r'^[a-zA-Z0-9]+$');
  if (!regex.hasMatch(value)) {
    return message ?? 'Only alphanumeric characters are allowed';
  }
  return null;
}