BetRoundController.php

<?php
    /**
     * Finds and displays a BetRound entity.
     *
     * @Route("/{id}/add", name="betround_add")
     * @ParamConverter("betRound", class="StregoTippBundle:BetRound")
     * @Template()
     */
    public function addAction(BetRound $betRound)
    {

        $user = $this->getSecurityContext($betRound)->getToken()->getUser();
        $userGroup = new UserGroup();
        foreach ($betRound->getUsers() as $user) {
            $userGroup->addUser($user);
        }
        $form = $this->createForm(new UserGroupQuickType(), $userGroup);

        $request = $this->getRequest();

        if ('POST' === $request->getMethod()) {

            $form->submit($request);
            if ($form->isValid()) {
                /** @var $myUserManager UserManager */
                $myUserManager = $this->container->get('strego_user.user_manager');

                $group = $form->getData();

                foreach ($group->getUsers() as $toInvite) {
                    if (!$betRound->getUserGroup()->hasUser($toInvite)) {
                        $myUserManager->joinGroup($betRound->getUserGroup(), $toInvite);
                    }
                }
                $this->getDoctrine()->getManager()->flush();
                $this->get('session')->getFlashBag()->add('success', 'Erfolgreich eingeladen!');

                return $this->redirect($this->generateUrl('betround_show', array('id' => $betRound->getId())));
            }
        }

        return array(
            'form' => $form->createView(),
            'betRound' => $betRound
        );
    }

UserGroupGroupController.php

<?php 
  /**
     *
     * @Route("/{slug}/add", name="strego_user_group_add")
     * @ParamConverter("userGroup", class="StregoUserBundle:UserGroup")
     * @Template()
     */
public function addAction(UserGroup $userGroup)
{
      $tempGroup = new UserGroup();
      foreach ($userGroup->getUsers() as $user) {
           $tempGroup->addUser($user);
      }
      $form = $this->container->get('form.factory')->create(new UserGroupQuickType(), $tempGroup);

      $request = $this->container->get('request');

      if ('POST' === $request->getMethod()) {
           $form->submit($request);

           if ($form->isValid()) {
               $group = $form->getData();

               /** @var $myUserManager UserManager */
               $myUserManager = $this->container->get('strego_user.user_manager');
               /** @var $em EntityManager */
               $em = $this->container->get('em');

              foreach ($group->getUsers() as $toInvite) {
                $myUserManager->joinGroup($userGroup, $toInvite);
              }
           $em->persist($userGroup);
               $em->flush($userGroup);

           }
      }

      return array(
             'form' => $form->createView(),
             'userGroup' => $userGroup
      );
}

UserGroupManager.php

<?php
public function joinGroup(UserGroup $userGroup, User $user = null)
    {
        if ($user === null) {
            $user = $this->securityContext->getToken()->getUser();
        }
        if (!$userGroup->getUsers()->contains($user)) {
            print('<br>invite:' . $user);
            $userGroup->addUser($user);
            $this->em->persist($userGroup);
            $this->dispatcher->dispatch(
                UserEvents::USER_USERGROUP_JOIN,
                new UserGroupUserEvent($userGroup, $user)
            );
        } else {
            print('<br>is already in:' . $user);
        }
    }