在Django新版本中替换DateModifierNode是什么 [英] What is the replacement for DateModifierNode in new versions of Django

问题描述

我想基于模型的两个字段执行查询，日期，由int的偏移量，用作timedelta

I want to do a query based on two fields of a model, a date, offset by an int, used as a timedelta

model.objects.filter(last_date__gte=datetime.now()-timedelta(days=F('interval')))

是一个不要去，因为F（）表达式不能传递给timedelta

is a no-go, as a F() expression cannot be passed into a timedelta

有一点挖掘，我发现 DateModifierNode - 虽然它似乎在此提交中被删除： https://github.com/django/django/commit/cbb5cdd155668ba771cad6b975676d3b20fed37b （从这个现在过时的SO问题 Django：在查询中的datetime.timedelta中使用F参数）

A little digging, and I discovered DateModifierNode - though it seems it was removed in this commit: https://github.com/django/django/commit/cbb5cdd155668ba771cad6b975676d3b20fed37b (from this now-outdated SO question Django: Using F arguments in datetime.timedelta inside a query)

提交提到：

.dates（）查询我们通过使用自定义Query，QuerySet，
和编译器类来实现。而是通过使用表达式和
数据库转换器API实现它们。

The .dates() queries were implemented by using custom Query, QuerySet, and Compiler classes. Instead implement them by using expressions and database converters APIs.

这听起来很合理，就像应该还要快一点简单的方法 - 但是我一直在无尽地寻找如何做到这一点太长时间 - 任何人都知道答案？

which sounds sensible, and like there should still be a quick easy way - but I've been fruitlessly looking for how to do that for a little too long - anyone know the answer?

推荐答案

在Django 1.10中有一个比较简单的方法，但是您需要更改一些模型：使用DurationField。我的模型如下：

In Django 1.10 there's simpler method to do it but you need to change the model a little: use a DurationField. My model is as follows:

class MyModel(models.Model):

    timeout = models.DurationField(default=86400 * 7)  # default: week
    last = models.DateTimeField(auto_now_add=True)

，查找 last 之前的对象在之前减去$ code> timeout 是：

and the query to find objects where last was before now minus timeout is:

MyModel.objects.filter(last__lt=datetime.datetime.now()-F('timeout'))

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