public function createFavourite(User $user, ResourceNode $resourceNode)
    {
        $favourite = $this->repo->findOneBy(['user' => $user, 'resourceNode' => $resourceNode]);

        if (empty($favourite)) {
            $favourite = new Favourite();
            $favourite->setUser($user);
            $favourite->setResourceNode($resourceNode);
            $this->om->persist($favourite);
            $this->om->flush();
        }
    }