validateUsername static method

String? validateUsername(
  1. String? value,
  2. BuildContext context
)

Validates a username based on specific criteria:

  • Must not be empty
  • Must match the regex pattern for valid usernames (lowercase letters, digits, dots, and underscores)
  • Must be at least 4 characters long @param value The username string to validate. @param context The BuildContext for localization. @return A string error message if validation fails, or null if it passes.

Implementation

static String? validateUsername(String? value, BuildContext context) {
  if (value!.isEmpty) return AppLocalizations.of(context)!.tUserNameCannotEmpty;
  if (!RegExp(r'^[a-z0-9._]+$').hasMatch(value)) return AppLocalizations.of(context)!.tInvalidUserName;
  if (value.length < 4) return AppLocalizations.of(context)!.tUserNameLength;
  return null;
}