Django Delete all but last five of queryset

Question

I have a super simple django model here:

class Notification(models.Model):
    message = models.TextField()
    user = models.ForeignKey(User)
    timestamp          


        

Answer 1

Use an inner query to get the set of items you want to keep and then filter on them.

objects_to_keep = Notification.objects.filter(user=user).order_by('-created_at')[:5]
Notification.objects.exclude(pk__in=objects_to_keep).delete()

Double check this before you use it. I have found that simpler inner queries do not always behave as expected. The strange behavior I have experienced has been limited to querysets that are just an order_by and a slice. Since you will have to filter on user, you should be fine.