Django模型在两个DateTimeFields之间经过的时间

问题描述

我对django刚起步，还无法找到一种方法来获取两个DateTimeFields之间的经过时间并将其保存到另一个模型中。

I am pretty new to django and haven't been able to find a way to get the elapsed time between two DateTimeFields and save it to another model.

from django.db import models



class Timesheet(models.Model):
    startTime = models.DateTimeField(auto_now_add=True)
    endTime = models.DateTimeField(blank=True, null=True)
    duration = models.DateTimeField(endTime - startTime)

    def _str_(self):
        return self.startTime

如何使工期= endTime-startTime？
我也在使用PostgreSQL数据库。

How can I make duration = endTime - startTime?I am also using a PostgreSQL database.

推荐答案

在此期间，我不会使用专用的模型字段。

I wouldn't use a dedicated model field for the duration.

我会在模型上使用属性代替相同的功能。

I would use a property on the model instead for the same functionality.

类似的东西：

@property
def duration(self)
    return self.end_time - self.startime

卢卡斯有一个很好的主意使用注释，但是如果某个Timesheet实例不是来自该对象管理器的，并且之前未进行注释，则必须进行单独的数据库匹配才能真正对其进行注释。

Lucas has a good idea of using an annotation, but if you have a Timesheet instance somewhere that didn't come from that object manager and was not previously annotated, you would have to do a separate database hit to actually annotate it.

该属性的用法如下：

some_timesheet_instance.duration

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