在Django的queryset中总结一个字段

Question

models.py

class QaCommission(models.Model):
    user = models.ForeignKey(PlUser, on_delete=models.CASCADE, blank=True, null=True, related_name='user_commission')
    ref = models.ForeignKey(PlUser, on_delete=models.CASCADE, blank=True, null=True, related_name='ref_commission')
    price = models.FloatField(blank=True, null=True)
    pct = models.FloatField(blank=True, null=True)
    commission = models.FloatField(blank=True, null=True)
    status = models.IntegerField(blank=True, null=True, default=0)

serializers.py

class QaCommissionSerializer(serializers.ModelSerializer):
    class Meta:
        model = QaCommission
        fields = '__all__'

views.py

class QaCommissionList(viewsets.ModelViewSet):
    queryset = QaCommission.objects.all()
    serializer_class = QaCommissionSerializer

如果我们在此视图中过​​滤ref = 60，则结果显示如下：

{
"count": 18,
"next": "http://127.0.0.1:8008/api/qacommission/?ref=60&page=2",
"previous": null,
"results": [
    {
        "id": 1,
        "price": 20.0,
        "pct": 0.1,
        "commission": 2.0,
        "status": 1,
        "user": 7,
        "ref": 60
    },
    {
        "id": 2,
        "price": 10.0,
        "pct": 0.1,
        "commission": 1.0,
        "status": 1,
        "user": 7,
        "ref": 60
    },
    ......
    ......
    ......
    {
        "id": 10,
        "price": 15.0,
        "pct": 0.1,
        "commission": 1.5,
        "status": 1,
        "user": 7,
        "ref": 60
    }
]
}

我想对结果中的所有“佣金”字段进行汇总，然后将总和附加到原始查询集（也许在“计数”旁边：18），如上所示，有18个佣金需要计数。

我该如何实施？ 需要您的帮助，谢谢！

Answer 1

尝试覆盖ModelViewset list()方法，

class QaCommissionList(viewsets.ModelViewSet):
    queryset = QaCommission.objects.all()
    serializer_class = QaCommissionSerializer

    def list(self, request, *args, **kwargs): response = super().list(request, *args, **kwargs) response.data['sum'] = sum([data.get('commission', 0) for data in response.data['results']]) return response

这样的回答和行动的commision 从特定的页面 ，并显示它

UPDATE

from django.db.models import Sum


class QaCommissionList(viewsets.ModelViewSet):
    queryset = QaCommission.objects.all()
    serializer_class = QaCommissionSerializer

    def list(self, request, *args, **kwargs): response = super().list(request, *args, **kwargs) if 'ref' in request.GET and request.GET['ref']: response.data['sum'] = QaCommission.objects.filter(ref=int(request.GET['ref']) ).aggregate(sum=Sum('commission'))['sum'] return response

上面的答案将返回带有过滤器的“ commission总额”列（与分页无关）

感谢@bruno提到这样的观点