private function hasUploadField($field, $definedField)
    {
        // check for string key
        if (array_has($definedField, $field)) {
            return true;
        }

        // check for value
        $found = false;
        foreach ($definedField as $key => $val) {
            $found = (is_numeric($key) && $val === $field);

            if ($found) {
                break;
            }
        }

        return $found;
    }