public static function propertyIsValid($property_name, &$property_value, &$error) { if (!parent::propertyIsValid($property_name, $property_value, $error)) { return false; } if ($property_name === EVENT_TYPE_PARTY_LAUNCH_KEY_LAUNCH_ITEM_TITLE) { // Item title is a string // if (!isset($property_value) || !is_string($property_value)) { $error = Error::withDomain(VALIDATION_ERROR_DOMAIN, VALIDATION_ERROR_CODE_INVALID_PROPERTY, $property_name . " should be a valid string."); return false; } } return true; }