TYPO3 ConnectionPool find a file after the uid of the file reference and update data

The concept is that, after a successfull save of my object, it should update a text in the database (With a Hook). Lets call the field 'succText'. The table i would like to access is the sys_file but i only get the sys_file_reference id when i save the object. So i thought i could use the ConnectionPool to select the sys_file row of this file reference and then insert the data on the field 'succText'.

I tried this:

public function processDatamap_preProcessFieldArray(array &$fieldArray, $table, $id, \TYPO3\CMS\Core\DataHandling\DataHandler &$pObj) {
    $queryBuilder = GeneralUtility::makeInstance(ConnectionPool::class)->getQueryBuilderForTable('sys_file_reference');
    $findItemsId = $queryBuilder
       ->select('*')
       ->from('sys_file_reference')
       ->join(
          'sys_file_reference',
          'sys_file',
          'reference',
          $queryBuilder->expr()->eq('reference.uid', $queryBuilder->quoteIdentifier('uid_local'))
       )
       ->where(
            $queryBuilder->expr()->eq('uid_local', $queryBuilder->createNamedParameter($fieldArray['downloads'], \PDO::PARAM_INT))
       )
      ->execute();
}

But this give me back the sys_file_reference id and not the id and the field values of the sys_file table.

As for the update, i havent tried it yet, cause i haven't figured out yet, how to get the row that needs to be updated. I gues with a subquery after the row is found, i don't really know.

The processDatamap_preProcessFieldArray is going to be renamed to post. I only have it this way in order to get the results on the backend.

Thanks in advance,

You might want to make use of the FileRepository class here.

$fileRepository = GeneralUtility::makeInstance(\TYPO3\CMS\Core\Resource\FileRepository::class);
$fileObjects = $fileRepository->findByRelation('tablename', 'fieldname', $uid);

Where $uid is the ID of the record that the files are connected to via file reference.

You will get back an array of file objects to deal with.