doctrine2 constraint violation - php

Question

I have the following entity with this rekation:
/**
* Acme\DemoBundle\Entity\Book
*
* #ORM\Table(name="book")
* #ORM\Entity(repositoryClass="Acme\DemoBundle\Repository\BookRepository")
* #ORM\HasLifecycleCallbacks
* #UniqueEntity(fields="publickey", groups={"publickey"})
*/
class P1guestlistentry {
/**
* #var P1guestlistentrystatistic
*
* #ORM\OneToOne(targetEntity="P1guestlistentrystatistic", orphanRemoval=true, cascade={"all"}, fetch="EAGER")
* #ORM\JoinColumns({
* #ORM\JoinColumn(name="fkstatistic", referencedColumnName="pkId", nullable=false)
* })
*/
private $fkstatistic;
When I try to remove an object like here:
$this->getEntityManager()->getConnection()->beginTransaction();
try{
$book = $this->getEntityManager()->getRepository('AchmeDemoBundle:Book')->find(3928);
$this->getEntityManager()->remove($book);
$this->getEntityManager()->flush();
$this->getEntityManager()->getConnection()->commit();
}catch(Exception $e){
$this->getEntityManager()->getConnection()->rollBack();
echo $e->getMessage();
}
exit;
I can do whatever I want, I get the following error:
An exception occurred while executing 'DELETE FROM book WHERE pkId = ?' with params {"1":3928}: SQLSTATE[23000]: Integrity constraint violation: 1451 Cannot delete or update a parent row: a foreign key constraint fails (p1.book, CONSTRAINT FK_F51A442F78734022 FOREIGN KEY (fkstatistic) REFERENCES bookstatistic (pkId))
Has anbybody an idea what I'm doing wrong?
I tried a lot of methods but nothing helps.

Answer 1

In case someone runs into a similar issue, here is the solution:
/**
* #var statistic
*
* #ORM\OneToOne(targetEntity="statistic", cascade="ALL")
* #ORM\JoinColumns({
* #ORM\JoinColumn(name="fkStatistic", referencedColumnName="pkId", onDelete="SET NULL")
* })
*/
The onDelete option will remove the relation first and then doctrine will do the cascade operation.