如何使用django为数据库中的列计算具有相同值的连续行？

Question

My App consists of a notification module. If the notifications are consecutively arrived from a same user, I would like to show "n notifications from john doe".

eg:

5 notifications from john doe
2 notification from james
4 notofications from john doe

How would I count these consecutive rows with same value in a column using django orm?

Answer 1

Suppose You have a model Notifications and another model named User . Then you can group by user_id

q=Notifications.objects.filter(user__id=1).values('user__first_name', 'user_id').annotate(c=Count('user__id'))

Answer 2

Just as Shafikur's answer above but I suppose you will have something to denote that the notification is new or hasn't been read. So let's add one more piece to the filter:

q=Notification.objects.filter(user__id=1, status='new').values('user__first_name', 'user_id').annotate(c=Count('user__id'))

It's not certain how you track the new notifications in your model, so this is just a rough guess which you should be able to apply to your particular case