如何使用Django ORM进行查询，以便基于特定组中的datetime字段返回最新条目？

Question

I have a model with datetime field which is the time stamp of when the row was added and in this model/table continuous entries are being made at certain intervals from various sources which are referenced through a name which is also a field in the model.

I need to form a query so that I will fetch the row with latest datetime when grouped by name.

ie lets say for example table is something like this:

timestamp              entry_name
22 march 12:30         First
22 march 12:32         Second
22 march 12:42         First
22 march 12:50         Second

My query should result in:

22 march 12:42         First
22 march 12:50         Second

As they are the latest entries with respect to "First" and "Second" group.

Now using raw query its pretty straight forward:

select *,max(datetime) from entry_table GROUP BY entry_name;

Is there any simple way to do this through the ORM?

Thanks in advance!

Answer 1

I use this in my own projects. The order_by and values make it group by name

from django.db import models
Model.objects.order_by('name').values('name').annotate(max_timestamp=models.Max("timestamp"))