models.py 文件源码

def get_exclusive_user(self, event):
        if self.inventory.multiple_assignments:
            return None

        try:
            return UsedItem.objects.get(item=self, helper__event=event,
                                        timestamp_returned=None).helper
        except UsedItem.DoesNotExist:
            raise NotAssigned
        except MultipleObjectsReturned:
            raise InvalidMultipleAssignment()