models.py 文件源码

def get_queryset(self):
        return super().get_queryset() \
            .annotate(ticket_count=models.Sum(
                models.Case(
                    models.When(
                        orderitem__order__refunded=True,
                        then=0
                    ),
                    models.When(
                        orderitem__order__billed_total='',
                        then=0
                    ),
                    models.When(
                        orderitem__order__billed_total__isnull=True,
                        then=0
                    ),
                    default=1,
                    output_field=models.IntegerField(),
                ))) \
            .annotate(sold_out=models.Case(
                          models.When(
                              ticket_count__lt=F('capacity'),
                              then=models.Value(False),
                          ),
                          default=True,
                          output_field=models.BooleanField(),
                        ))