(doctrine2 + symfony2) cascading remove : integrity constraint violation 1451

onDelete="CASCADE" also works fine. But don't forget to run app/console doctrine:schema:update --force before DB level changes will take an effect.

orphanRemoval some times doesn't work because it depends on (gets schedulled in) PersistencCollection. And we might be calling ArrayCollection#removeElement().

Following is a snippet of the PersistencCollection#remove()

    if ($this->association !== null &&
        $this->association['type'] & ClassMetadata::TO_MANY &&
        $this->owner &&
        $this->association['orphanRemoval']) {
        $this->em->getUnitOfWork()->scheduleOrphanRemoval($removed);
    }

and ArrayCollection does not do that.

Use onDelete="CASCADE" if you are using annotation

/**
 * @ORM\ManyToOne(targetEntity="Report", inversedBy="responses")
 * @ORM\JoinColumn(name="reportId", referencedColumnName="id",onDelete="CASCADE")
 */

Use onDelete: CASCADE if you are using yml

joinColumn:
      name: pid
      referencedColumnName: id
      onDelete: CASCADE

So, thanks to this French forum, I fixed the problem.

I needed to add nullable=true & onDelete="SET NULL" in @ORM\JoinColumn

Here is the workable configuration, maybe it will help someone :

#User.
    /**
     * @ORM\OneToMany(targetEntity="\sfCommands\ContentBundle\Entity\Application", mappedBy="user", cascade={"remove"}, orphanRemoval=true)
     * @ORM\OrderBy({"name" = "ASC"})
     */
    protected $applications;

    /**
     * @ORM\OneToOne(targetEntity="\sfCommands\ContentBundle\Entity\Entity")
     * @ORM\JoinColumn(name="entity1_id", referencedColumnName="id", nullable=true, onDelete="SET NULL")
     */
    private $entity1;

    /**
     * @ORM\OneToOne(targetEntity="\sfCommands\ContentBundle\Entity\Entity")
     * @ORM\JoinColumn(name="entity2_id", referencedColumnName="id", nullable=true, onDelete="SET NULL")
     */
    private $entity2;

#Application.
    /**
     * @ORM\OneToMany(targetEntity="\sfCommands\ContentBundle\Entity\Bundle", mappedBy="application", cascade={"remove"}, orphanRemoval=true)
     * @ORM\OrderBy({"name" = "ASC"})
     */
    protected $bundles;

    /**
     * @ORM\ManyToOne(targetEntity="\sfCommands\UserBundle\Entity\User", inversedBy="applications", cascade={"persist"})
     * @ORM\JoinColumn(name="user_id", referencedColumnName="id", nullable=true, onDelete="SET NULL")
     */
    protected $user;

#Bundle.
    /**
     * @ORM\ManyToOne(targetEntity="\sfCommands\ContentBundle\Entity\Application", inversedBy="bundles", cascade={"persist"})
     * @ORM\JoinColumn(name="application_id", referencedColumnName="id", nullable=true, onDelete="SET NULL")
     */
    protected $application;

    /**
     * @ORM\OneToMany(targetEntity="\sfCommands\ContentBundle\Entity\Entity", mappedBy="bundle", cascade={"remove"}, orphanRemoval=true)
     * @ORM\OrderBy({"name" = "ASC"})
     */
    protected $entitys;

#Entity.
    /**
     * @ORM\ManyToOne(targetEntity="\sfCommands\ContentBundle\Entity\Bundle", inversedBy="entitys", cascade={"persist"})
     * @ORM\JoinColumn(name="bundle_id", referencedColumnName="id", nullable=true, onDelete="SET NULL")
     */
    protected $bundle;