validate method

@override String? validate(BuildContext context, String fieldName, String? value)

Function to validate the form input. It takes a string and returns an String error message if the input is invalid or null if the input is valid.

Implementation

@override
String? validate(
  BuildContext context,
  String fieldName,
  String? value,
) {
  _isValid = true;
  _shortErrorMessage = null;
  _longErrorMessage = null;

  for (final validator in _validators) {
    final error = validator.validate(context, fieldName, value);
    if (error != null) {
      _isValid = validator.isValid;
      _shortErrorMessage = validator.shortErrorMessage;
      _longErrorMessage = validator.longErrorMessage;
      return error;
    }
  }

  return null;
}