Nested setFetchMode

[gharlan]

Feature Request

Q	A
New Feature	yes
RFC	no
BC Break	no

Summary

At the moment I'm using partial queries for fetching nested entities:

$qb = $this->createQueryBuilder('mail');
// ...
$mails = $qb->getQuery()->getResult();

$qb = $this->createQueryBuilder('mail');
$qb->select("PARTIAL mail.{id}, recipient, user");
$qb->andWhere("mail IN (:mails)")->setParameter('mails', $mails);
$qb->leftJoin('mail.recipients', 'recipient');
$qb->leftJoin('recipient.user', 'user');

Now I'm trying to convert this to setFetchMode (#8391) because partial queries are removed in v3. I've tried this:

$qb = $this->createQueryBuilder('mail');
// ...
$query = $qb->getQuery();

$query->setFetchMode(Mail::class, 'recipients', ClassMetadata::FETCH_EAGER); // this works great
$query->setFetchMode(MailRecipient::class, 'user', ClassMetadata::FETCH_EAGER); // this does not work

$mails = $query->getResult();

The second setFetchMode call does not have any effect. It would be great if setFetchMode would work for nested relations.

Or is there any other (good) replacement for my partial query?