向.aggregate()喂食**kwargs

Question

有可能做这样的事吗？

outputs = {"total_kgs": "kgs"}
Model.objects.all().aggregate(**outputs)

代替：

Model.objects.all().aggregate(total_kgs="kgs")

现在我得到了：

AttributeError：'str‘对象没有属性'resolve_expression’

以下是我目前正在努力做的事情：

InventoryManager级(经理)：

def lookup(self, operators, fields, status, labels=None):
    outputs = {}

    if status == "unsold":
        operators.update({"status__lt": choices.SOLD})

    q = [Q(**operators)]

    for field in fields:
        label = labels.pop(0) if labels else "{}_total".format(field)
        outputs.update({label: field})

    return self.model.objects.filter(reduce(operator.and_, q)).aggregate(**outputs)

def total_kgs(self, status='unsold'):

    operators = {"supplier__market__weights": "KGS"}
    operators.update({'supplier__market__currency_code':"INR"})
    return self.lookup(operators, ["weight", "invoice_value"], status)

相关示范数据：

class Purchase(models.Model):
    invoice = models.CharField(max_length=24, unique=True)
    lbs = models.DecimalField(decimal_places=4, max_digits=48, blank=True, null=True)
    kgs = models.DecimalField(decimal_places=4, max_digits=48, blank=True, null=True)
    invoice_value = models.DecimalField(decimal_places=4, max_digits=48, blank=True, null=True)
    status = models.IntegerField(choices=choices.STATUS_CHOICES, default=choices.PENDING)

最后，我想对每个查询做些什么：

self.model.objects.filter(reduce(operator.and_, q)).aggregate(total_weight=Coalesce(Sum("weight"), 0))

Answer 1

所以你知道了。如果插入正确的表达式，它就能正常工作。再次感谢。

for field in fields:
    label = labels.pop(0) if labels else "{}_total".format(field)
    outputs.update({label: Coalesce(Sum(field), 0)})