protected function onBeforeDelete() { parent::onBeforeDelete(); foreach ($this->Votes() as $e) { $e->delete(); } foreach ($this->Comments() as $e) { $e->delete(); } foreach ($this->ChangeRequests() as $e) { $e->delete(); } foreach ($this->Materials() as $e) { $e->delete(); } $this->Topics()->removeAll(); $this->Speakers()->removeAll(); }