如何在django ORM中获得最大值

Question

>>> AuthorizedEmail.objects.filter(group=group).values('added')
[{'added': datetime.datetime(2012, 5, 19, 13, 8, 7)}, 
{'added': datetime.datetime(2012, 5, 19, 13, 8, 7)}, 
{'added': datetime.datetime(2012, 5, 19, 13, 7, 23)}, 
{'added': datetime.datetime(2012, 5, 19, 13, 8, 7)}]

在这里获得最大值的最佳方法是什么？在python中还是在ORM中？

Answer 1

来自documentation：

>>> from django.db.models import Max
>>> AuthorizedEmail.objects.aggregate(Max('added'))

并获取模板中的值：

{{ item.added__max }}

Answer 2

latest根据added日期返回表中的最新对象：

AuthorizedEmail.objects.filter(group=group).latest('added')

Answer 3

AuthorizedEmail.objects.filter(group=group).order_by('-added')[0]

Answer 4

https://docs.djangoproject.com/en/dev/topics/db/aggregation/

https://docs.djangoproject.com/en/dev/topics/db/aggregation/#cheat-sheet