Django聚合：两个字段的乘法求和 [英] Django Aggregation: Summation of Multiplication of two fields

问题描述

我有一些模型这样的东西

I have a model some thing like this

class Task(models.Model):
   progress = models.PositiveIntegerField()
   estimated_days = models.PositiveIntegerField()

现在我想做在数据库级别计算 Sum（progress * estimated_days）。使用Django聚合我可以为每个字段的和，而不是字段乘法的总和。

Now I would like to do a calculation Sum(progress * estimated_days) on the database level. Using Django Aggregation I can have the sum for each field but not the summation of multiplication of fields.

推荐答案

更新：为 Django> = 1.8 由@kmmbvnr提供

Update: for Django >= 1.8 please follow the answer provided by @kmmbvnr

可以使用Django ORM：

it's possible using Django ORM:

这是你应该做的：

from django.db.models import Sum

total = ( Task.objects
            .filter(your-filter-here)
            .aggregate(
                total=Sum('progress', field="progress*estimated_days")
             )['total']
         )

注意：如果两个字段的类型不同，则说 integer & float ，您要返回的类型应作为 Sum

Note: if the two fields are of different types, say integer & float, the type you want to return should be passed as the first parameter of Sum

这是一个迟到的答案，但我想这可以帮助寻找相同的人。

It's a late answer, but I guess it'll help someone looking for the same.

这篇关于Django聚合：两个字段的乘法求和的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！