private function createSliceID()
    {
        $urlFilter = URLSegmentFilter::create();
        if ($sliceID = $urlFilter->filter($this->getField('Title'))) {
            if (!$this->Parent()->PageSlices()->filter(array('ID:not' => $this->ID, 'SliceID' => $sliceID))->exists()) {
                $this->setField('SliceID', $sliceID);
            } else {
                $this->setField('SliceID', "$sliceID-{$this->ID}");
            }
        }
    }