Removing an object with em->remove($user) removes all objects in table - symfony

Question

I have a User entity that implements UserInterface to use with a RBAC system. I have not implemented the whole system yet. However, when I try to remove a user with the following code, the action removes all the users and other associated objects in other tables and then throws me an error. I am able to remove objects from other entities without issues.
User entity
class User implements UserInterface
{
**
* #var integer $id
*
* #ORM\Column(name="id", type="smallint")
* #ORM\Id
* #ORM\GeneratedValue(strategy="AUTO")
*
protected $id;
**
* #var string $username
*
* #ORM\Column(name="username", type="string", length=20, unique=TRUE)
*
protected $username;
**
* #var string $password
*
* #ORM\Column(name="password", type="string", length=255)
*
protected $password;
**
* #var string $salt
*
* #ORM\Column(name="salt", type="string", length=255)
*
protected $salt;
**
* #var string $fullName
*
* #ORM\Column(name="full_name", type="string", length=60, unique=TRUE)
*
protected $fullName;
**
* #ORM\ManyToMany(targetEntity="Role", inversedBy="users", cascade={"persist", "remove"})
* #ORM\JoinTable(name="users_roles")
*
* #var ArrayCollection $userRoles
*
protected $userRoles;
public function __construct()
{
$this->userRoles = new ArrayCollection();
}
}
Delete action
public function deleteUserAction($id) {
$user = $em->getRepository('ACMECompanyBundle:User')->find($id);
$currentUser = $this->get('security.context')->getToken()->getUser();
if ($id == $currentUser->getId()) {
return new Response("You cannot delete the current user");
}
if (!$user) {
throw $this->createNotFoundException('No user found for id '.$id);
}
try {
$em->remove($user);
$em->flush();
$msg = "User deleted!";
$code = "OK";
} catch (DBALException $e) {
return new Response($e);
$msg = "User cannot be deleted!";
$code = "ERR";
}
$response = new Response(json_encode(array('code' => $code, 'msg' => $msg)));
$response->headers->set('Content-Type', 'application/json');
return $response;
}
The error returned after all users are removed is
InvalidArgumentException: You cannot refresh a user from the EntityUserProvider that does not contain an identifier. The user object has to be serialized with its own identifier mapped by Doctrine.

Answer 1

You left out the definition for em in your action... define it with
$em = $this->getDoctrine()->getEntityManager();
and it should work. Unless you set it on the class itself, then you would need $this->...

Answer 2

When doctrine removes the user, it also removes all rolles assigned to this user and all users assigned to these roles. So according your annotation schema this is the correct behavior because of cascade={"remove"} in $userRoles annotation and cascade={"remove"} in $users annotation in Role entity.
If you want to prevent cascade removing and want to keep cascade persistent remove "remove" argument from both user and role relations