Django正确运算总计

Question

我正在尝试获取所有item.estimated_cost的总数，我可以使用var ...

 batches = Batch.objects.for_user_pending(request.user)
    total_estimated_cost = 0
    for item in batches:
        total_estimated_cost =+ item.estimated_cost

但是我收到了这个错误：

一元+的错误操作数类型：'instancemethod'

* 模型方法*

def estimated_cost(self):
        return len(self.content) / 160 + 1 * self.group.contact_set.count()

Answer 1

def estimated_cost(self):
    return (int(len(self.content)) / 160) + (1 * int(self.group.contact_set.count()))

batches = Batch.objects.for_user_pending(request.user)
total_estimated_cost = 0
for item in batches:
    total_estimated_cost += item.estimated_cost()