Typo3 8.7.x / Extbase：如何获取页面的 sys_category

Question

can somebody tell me how to get the sys_category of a page at my controller of my extension?

public function listAction()
{
//get the sys categories of (a) page
???

Thanks

Answer 1

Now I wrote a solution with QueryBuilder. Maybe it could help someone else:

In my extension->controller

/**
 * pagesRepository
 *
 * @var \TYPO3\CMS\Frontend\Page\PageRepository
 * @inject
 */
protected $pageRepository = null;

In my extension->controller->someaction:

    foreach ($GLOBALS['TSFE']->rootLine as $page) {

        $pageObject = $this->pageRepository->getPage($page['uid']);

        if ($pageObject['categories']) {
            $queryBuilder = GeneralUtility::makeInstance(\TYPO3\CMS\Core\Database\ConnectionPool::class)->getQueryBuilderForTable('sys_category');
            $query = $queryBuilder->select('sys_category.uid', 'sys_category.title')->from('sys_category');
            $query->join(
                'sys_category',
                'sys_category_record_mm',
                'mm',
                $queryBuilder->expr()->andX(
                    $queryBuilder->expr()->eq('mm.uid_local', $queryBuilder->quoteIdentifier('sys_category.uid')),
                    $queryBuilder->expr()->in('mm.uid_foreign', $page['uid']),
                    $queryBuilder->expr()->eq('mm.tablenames', $queryBuilder->quote('pages')),
                    $queryBuilder->expr()->eq('mm.fieldname', $queryBuilder->quote('categories'))
                )
            );

            $result = $query->execute()->fetchAll();

            break;
        }
    }