Django - 注释多个 Sum() 对象会给出错误的结果

Question

模型.py 看起来像这样

class Channel(Model):
    name = CharField()

class Contract(Model):
    channel = ForeignKey(Channel, related_name='contracts')
    fee = IntegerField()

class ContractPayment(Model):
    contract = ForeignKey(Contract, related_name='payments')
    value = IntegerField()

当我查询模型时:
Channel.objects.annotate(pay=Sum('contracts__fee'))
它返回: 75000 .它是正确的，但是当我这样查询时:

Channel.objects.annotate(pay=Sum('contracts__fee'))
               .annotate(paid=Sum('contracts__payments__value'))

它返回: 支付:96000，支付:33000 .如您所见 支付 被改变。这里发生了什么？我看了票 #10060但没有运气。

Answer 1

使用两个查询来获得所需的结果:

Channel.objects.annotate(pay=Sum('contracts__fee'))

和

Channel.objects.annotate(paid=Sum('contracts__payments__value'))