Keep only newest records using DQL - doctrine-orm

Question

I have a symfony app with doctrine. There is a table like:
+--------+---------------------+-------+
| user | log_date | foo |
+---------+---------------------+-------+
| john | 2018-03-20 22:59:18 | 58 |
| kyle | 2018-04-11 13:45:02 | 22 |
| paul | 2018-11-08 22:19:16 | 41 |
| kyle | 2018-08-14 09:39:26 | 19 |
| fred | 2018-03-28 06:08:31 | 24 |
| john | 2018-01-21 11:52:17 | 81 |
| ... | ... | ... |
+---------+---------------------+-------+
A cron should execute a symfony command to delete all records but keep the latest 10 of every user. Can this be done using DQL or do I have to use an SQL (sub-)query?

Answer 1

I think something like this in entity repository can get all the entries for the user except the last 10
public function getAllExceptLatest($user)
{
return $this
->createQueryBuilder('t')
->andWhere('t.logDate <= :logDate')
->orderBy('t.logDate', 'DESC')
->setParameter(':logDate', $this->getLatestDate($user))
->setFirstResult(10)
->getQuery()
->execute();
}
public function getLatestDate($user)
{
return $this->createQueryBuilder('e')
->select('MAX(e.logDate)')
->andWhere('e.user = :user')
->setParameter(':user', $user)
->getQuery()
->getSingleScalarResult();
}
And in controller you can use
public function keepLatest(){
$em = $this->getDoctrine()->getManager();
$userRepo = $em->getRepository(User::class);
$users = $userRepo->findAll();
foreach ($users as $u) {
$records = $userRepo->getAllExceptLatest($u);
foreach ($records as $r)
$em->remove($r);
}
$em->flush();
}
I didn't test this, but in mine apps similar methods works fine