Symfony - Avoid store related entities in preFlush Doctrine - symfony

Question

I have an entity Subject:
/**
*
* #ORM\Table()
* #ORM\HasLifecycleCallbacks()
*/
class Subject
{
//... Some fields
/**
* #ORM\OneToMany(targetEntity="Subject", mappedBy="mark", cascade={"persist", "remove"})
*/
private $subjects;
private function calculateMarks()
{
//... Do something
// return array with (abilities => marks);
}
/**
* #ORM\PrePersist()
*/
public function prePersist(){
$now = new \DateTime();
$this->setCreatedAt( $now );
$this->setModifiedAt( $now );
}
/**
* #ORM\PreUpdate()
*/
public function preUpdate(){
$this->setModifiedAt( new \DateTime() );
$this->setUpdated(true);
}
/**
* #ORM\PreFlush()
*/
public function preFlush(){
$marks = calculateMarks();
foreach($marks as $ability => $score){
$mark = new Mark();
$mark->setSubject( $this );
$this->addMark( $score );
$mark->setAbility( $ability );
}
}
}
and the class Mark:
class Mark{
// Many fields
/**
* #ORM\ManyToOne(targetEntity="Subject", inversedBy="subjects")
* #ORM\JoinColumn(name="subject_id", referencedColumnName="id")
*/
private $subject;
}
My problem is that I calculate and I create the Marks in the preFlush event (this is done this because in the official documentation is said this about preUpdate event: "Changes to associations of the updated entity are never allowed in this event, since Doctrine cannot guarantee to correctly handle referential integrity at this point of the flush operation"). When I save one subject, all work fine, but when I save many Subjects at the same time in a webservice, some marks are stored in the database many times.
The webservice action below:
public function setSubjects(Request $request)
{
//... Do something
$subjects = $request["Subjects"];
foreach($subjects as $s){
$em = $this->getDoctrine()->getManager();
//... Do something
$em->persist($s);
$em->flush();
}
return new JsonResponse($response);
}
Has anybody an idea of how could I avoid this behavior in the preFlush event?
Thanks in advance.

Answer 1

I always try to avoid LifecycleCallbacks unless it's simple and i'm only changing properties in the same entity.
to solve your issue i would create a function calculateMarks() inside the entity and tweak my loop to be something like
$em = $this->getDoctrine()->getManager();
foreach($subjects as $s){
//... Do something
$s->calculateMarks();
$em->persist($s);
}
$em->flush();
NOTICE
avoid $em = $this->getDoctrine()->getManager(); & $em->flush(); inside the loop