Doctrine: Removing entity in self-referencing (many-to-many) - doctrine-orm

Question

I would like to ask your help in deleting association.
My User entity:
class User
{
...
/**
* #ORM\ManyToMany(targetEntity="User", mappedBy="following")
**/
private $followers;
/**
* #ORM\ManyToMany(targetEntity="User", inversedBy="followers")
* #ORM\JoinTable(name="friends",
* joinColumns={#ORM\JoinColumn(name="user_id", referencedColumnName="id")},
* inverseJoinColumns={#ORM\JoinColumn(name="friend_user_id", referencedColumnName="id")}
* )
**/
private $following;
I have two actions:
Profile:follow
// followAction
$entityManager = $this->getDoctrine()->getEntityManager();
$me->addFollowing($targetUser);
$targetUser->addFollower($me);
$entityManager->persist($me);
$entityManager->persist($targetUser);
$entityManager->flush();
Profile:unfollow
$entityManager = $this->getDoctrine()->getEntityManager();
$me->removeFollowing($targetUser);
$targetUser->removeFollower($me);
$entityManager->persist($me);
$entityManager->persist($targetUser);
$entityManager->flush();
Process of following is working in a proper way, and I see appropriate records friends table.
But when I am trying to unfollow user, I receive exception:
An exception occurred while executing 'INSERT INTO friends (user_id, friend_user_id) VALUES (?, ?)' with params {"1":2,"2":10}:
SQLSTATE[23000]: Integrity constraint violation: 1062 Duplicate entry '2-10' for key 'PRIMARY'
What am I doing wrong? I've tried with persist and without it, the same. Maybe something in association configs?

Answer 1

Your first mistake is 2 persist actions, you only need one. Check this:
// class User
public function switchFollowingUser(User $user)
{
if ( $this->following->contains($user) )
$this->following->removeElement($user) ;
else
$this->following->add($user) ;
}
and controller would be just
$follower->switchFollowingUser($user) ;
Extract this method into two methods if you want but I kinda prefer this way because it is shorter.
Second thing:
Did you put
$this->following = new ArrayCollection() ;
$this->followers = new ArrayCollection() ;
in __construct() ?
Try if this works.