events/Classes/Service/CleanupService.php

<?php

namespace Wrm\Events\Service;

use TYPO3\CMS\Core\DataHandling\DataHandler;
use TYPO3\CMS\Core\Database\Connection;
use TYPO3\CMS\Core\Database\ConnectionPool;
use TYPO3\CMS\Core\Database\Query\QueryBuilder;
use TYPO3\CMS\Core\Utility\GeneralUtility;

class CleanupService
{
    public function deleteAllData()
    {
        $this->truncateTables(... [
            'tx_events_domain_model_date',
            'tx_events_domain_model_organizer',
        ]);

        $dataHandler = GeneralUtility::makeInstance(DataHandler::class);
        /* @var DataHandler $dataHandler */
        $dataHandler->start([], $this->getDeletionStructure([
            'tx_events_domain_model_event',
        ]));
        $dataHandler->process_cmdmap();
    }

    private function truncateTables(string ...$tableNames): void
    {
        foreach ($tableNames as $tableName) {
            GeneralUtility::makeInstance(ConnectionPool::class)
                ->getConnectionForTable($tableName)
                ->truncate($tableName);
        }
    }

    private function getDeletionStructure(array $tableNames): array
    {
        $structure = [];

        foreach ($tableNames as $tableName) {
            $structure = array_merge($structure, $this->getDeletionStructureForTable($tableName));
        }

        return $structure;
    }

    private function getDeletionStructureForTable(string $tableName): array
    {
        $dataStructure = [$tableName=> []];

        foreach ($this->getRecordsToDelete($tableName) as $recordToDelete) {
            $dataStructure[$tableName][$recordToDelete] = ['delete' => 1];
        }

        return $dataStructure;
    }

    private function getRecordsToDelete(string $tableName): array
    {
        $queryBuilder = GeneralUtility::makeInstance(ConnectionPool::class)
            ->getConnectionForTable($tableName)
            ->createQueryBuilder();

        /* @var QueryBuilder $queryBuilder */
        $records = $queryBuilder->select('uid')
            ->from($tableName)
            ->execute()
            ->fetchAll();

        return array_map(function (array $record) {
            return $record['uid'];
        }, $records);
    }
}