减去两个注释列 [英] Subtracting two annotated columns

问题描述

我需要能够对两个注释列进行排序。

所以我想做这样的事情：

  c = c.annotate（metric = Sum（'results__metric'））
c = c.annotate（metric_prior = Sum（'results__metric_prior'）） 
c = c.annotate（variance = F（'metric'） -  F（'metric_prior'））＃不起作用，仅用于示范目的
  

然后：

  c = c.order_by（'variance'有没有人知道如何完成像上面这样的东西？
 
 
 
  div class =h2_lin>解决方案

实际上，

  c = c.annotate（variance = F（'metric'） -  F（'metric_prior'）
  

按照你想要的从Django 1.8开始 。

I need to be able to sort on the aggregate of two annotated columns

So I'd like to do something like this:

c = c.annotate(metric=Sum('results__metric'))
c = c.annotate(metric_prior=Sum('results__metric_prior'))
c = c.annotate(variance=F('metric')-F('metric_prior')) #doesn't work, for demonstrative purposes only

and then:

c = c.order_by('variance')

Does anyone know how to accomplish something like the above?

解决方案

Actually,

c = c.annotate(variance=F('metric')-F('metric_prior'))

works as you would like it to starting with Django 1.8.

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