/**
  * Validation for Unique in the db
  *
  * @param \string $value
  * @param \string $field Fieldname like "username" or "email"
  * @param \In2\Femanager\Domain\Model\User $user Existing User
  * @return \bool
  */
 protected function validateUniqueDb($value, $field, \In2\Femanager\Domain\Model\User $user = NULL)
 {
     $foundUser = $this->userRepository->checkUniqueDb($field, $value, $user);
     return !is_object($foundUser);
 }