public function checkValidity($data, $omitMandatoryCheck = false)
{
if (!$omitMandatoryCheck and $this->getMandatory() and empty($data)) {
throw new Model\Element\ValidationException("Empty mandatory field [ " . $this->getName() . " ]");
}
if (!empty($data)) {
$user = Model\User::getById($data);
if (!$user instanceof Model\User) {
throw new Model\Element\ValidationException("Invalid user reference");
}
}
}