trackers.py 文件源码

def get_start_date(self, qs):
        most_recent_kwargs = self.get_most_recent_kwargs()
        last_stat = self.statistic_model.objects.most_recent(
            **most_recent_kwargs)
        if last_stat:
            start_date = last_stat.date
        else:
            first_instance = qs.order_by(self.date_field).first()
            if first_instance is None:
                # No data
                return
            start_date = getattr(first_instance, self.date_field)
        if start_date and isinstance(start_date, datetime):
            if timezone.is_aware(start_date):
                start_date = timezone.make_naive(start_date).date()
            else:
                start_date = start_date.date()
        return start_date