TYPO3 Core

I have created an Ajax function to store the slug of a record in the pages table. This all happens in a Backend-Module.

Everything works as long as I leave the value for the function "set ('slug', ...)" as a string, for example "set ('slug', 'test')".

As soon as I add the function "createNamedParameter", only the default value ":dcValue2" is output. It does not matter if the parameter "\ PDO :: PARAM_STR" is added or not. If I add a placeholder as a third parameter, the placeholder is output.

However, in the where statement, the function works fine.

The following function saves ":dcValue2" into the database.

/**
     * action save
     *
     * @return void
     */
    public function saveAction(\Psr\Http\Message\ServerRequestInterface $request, \Psr\Http\Message\ResponseInterface $response)
    {
        $queryParams = $request->getQueryParams();
        $queryBuilder = GeneralUtility::makeInstance(\TYPO3\CMS\Core\Database\ConnectionPool::class)->getQueryBuilderForTable('pages');
        $statement = $queryBuilder
            ->update('pages')
            ->where(
                $queryBuilder->expr()->eq('uid', $queryBuilder->createNamedParameter($queryParams['uid'],\PDO::PARAM_INT))
            )
            ->set('slug',$queryBuilder->createNamedParameter('test'))
            ->execute();

        $output = 'Slug: '.$queryParams['slug'];
        $response->getBody()->write($output);
        return $response->withHeader('Content-Type', 'text/html; charset=utf-8');
    }