public function addValues(array $fieldValues)
    {
        foreach ($fieldValues as $fieldName => $values) {
            $values = Arr::cast($values);
            if (null === ($field = $this->getField($fieldName))) {
                $message = "unknown field";
                $len = count($values);
                if ($len !== 1) {
                    $message .= " (encountered $len values)";
                }
                $error = new Error($message);
                $error->setName($fieldName);
                $this->addError($error);
            }
            else {
                foreach ($values as $index => $value) {
                    $field->addValue($value, $index);
                }   
            }
        }
    }