username static method

String? username(
  1. String? value, {
  2. String message = '3–20 letters, numbers or underscores',
})

Validates a username.

Implementation

static String? username(String? value,
    {String message = '3–20 letters, numbers or underscores'}) {
  if (value == null || value.trim().isEmpty) return null;
  return Validators.isUsername(value) ? null : message;
}