private function fieldInMap($field, array $map) {
        $result = null;
        if (array_key_exists($field, $map)) {
            $result = $map[$field];

        } else if (!$this->isFieldCaseSensitive()) {
            $field = strtolower($field);
            //$map = array_map('strtolower', $map);
            if (array_key_exists($field, $map)) {
                $result = $map[$field];
            }
        }
        return $result;
    }