Cascade remove working fined but not when more than one entry... why?

Question

I am building an app where USERS can give a SCORE to some ANSWERS left by the community.

here the schema/relations of the entities:

ANSWER (one to many with) SCORE (many to one with) USER

I want that when i remove an ANSWER, the SCORES related to that ANSWER are also deleted...

BUT when I have more than one SCORE, then symfony triggers this exception:

 "SQLSTATE[23000]: Integrity constraint violation: 1451 Cannot delete or update a parent row: a foreign key constraint fails (`symfony`.`Score`, CONSTRAINT `FK_6F8F552A4AB7A507` FOREIGN KEY (`answer_id`) REFERENCES `Answer` (`id`))

I must say that it works fine if there is only one SCORE related to that answer. (strange?)

Here my entities: you will see that I do have the cascade={"remove"}, I emphasis the fact that SCORE id is build on ANSWER_ID and USER_ID. (because I want that a SCORE can only be delivered once for an answer by a user).

class=Answer
{
    /**
    * @ORM\OneToMany(targetEntity="XX\BlogBundle\Entity\Score", mappedBy="answer", cascade={"persist", "remove"})
    **/
    private $scores;

    /**
    * @param \XX\BlogBundle\Entity\Score $scores
    */
    public function removeScore(\XX\BlogBundle\Entity\Score $score)
    {
       $this->scores->removeElement($score);
    }

    // OTHER ATTRIBUTES ETC
}

.

class=Score
{
     /**
     * @ORM\Id
     * @ORM\ManyToOne(targetEntity="XX\BlogBundle\Entity\Anwer", inversedBy="scores") 
     */
     private $answer;

     /**
     * @ORM\Id
     * @ORM\ManyToOne(targetEntity="XX\BlogBundle\Entity\User", cascade={"persist"})
     */
     private $user;

/**
     * @var smallint
     * @ORM\Column(name="valeur", type="smallint", length=10, nullable=true)
     */
     private $value;

     // SETTER AND GETTER
}

.

class User
{
     /**
     * @ORM\Column(name="id", type="integer")
     * @ORM\Id
     * @ORM\GeneratedValue(strategy="AUTO")
     */
     private $id;

     /**
     * @var string
     * @ORM\Column(name="name", type="string", length=10)
     */
     private $name;
}

Answer 1

I would remove them manually instead of any cascade operations.. Something like this:

public function removeAnswerAction($id)
{
    ...

    $answer = /* ... */ ->find($id);
    foreach ($answer->getScores as $score) {
        $answer->removeScore($score);
        $score->setAnswer(null); // it requires setAnswer(Answer $answer = null), if you used a type hint in getter
        $em->remove($score); // you can remove it if you want..
    }

    $em->remove($answer);
    $em->flush();

    ...
}

I don't know how cascade=remove works with collections (I've never been interested in using cascade operations), but in your case doctrine is saying that it cant remove parent (Answer object) without deleting all its collection (related Score objects)..

Answer 2

Probleme solved (see below my exlanation) but not sure if it is the best way. (If anyone has a better solution?)

Actually the probleme doesn't come from the entities or the cascade remove (all that part is ok, maybe it can be optimised)

The issue come from the fact that I used an $answer object on which I had removed some of its scores (throught removeScore(score) in the controller before doing $em->remove($answer).

Also when symfony/doctrine tried to remove in cascade the scores associated to that $answer it couldn't find all of them and potentially would have create some orphin entries in the database, which triggered that exception.

So because I trully need to remove some scores from the $answer object, my solution is to store all thoses scores that I remove in an array so that I can add them to the $answer object before removing it.

$answer = $em->getRepository('XXBlogBundle:Answer')->find(1);
foreach($answer->getScores() as $score)
{
   // I REMOVE SOME SCORES HERE FROM THE ANSWER OBJECT
   if($score->getValue() == 0) 
   {
       $array_temp_save_score[] = $score;
       $answer->removeScore($score); 
   }
}
// SOME OF MY CODE WHERE I USE $ANSWER WITHOUT ALL SCORE
// ...
// END OF THAT PART

foreach($array_temp_save_score as $v) 
{
    $answer->addScore($v);
}
$em->remove($answer);
$em->flush();