def get_last_tid(self):
        try:
            spec = {'tid': {'$gt': 0}}
            sort = [('tid', -1)]
            row = self.db.docs.find_one(spec, sort=sort)
        except Exception as e:
            raise DatabaseException(e)
        if row:
            return row['tid']
        return 0
def _on_drag_data_received(self, dragged_item_index_str, destination_item):
    dragged_item = self._items[int(dragged_item_index_str)]
    self.reorder_item(dragged_item, self._get_item_position(destination_item))