django query get last n records

Lets say I am implementing a message stream, records sort by ID ascending order, each fetch request, I want to only allow to fetch the most latest 10 records.

I tried:

Messages.objects.filter(since=since)[:-10]

And I had an error saying Negative Indexing is not supported.

My current work around is sort ID descending order, and then run:

Messages.objects.filter(since=since)[:10]

But this requires the front end to reverse the order again.

My question is, is there a elegant way to do it?

Solution 1:

You can pass your queryset to reversed:

last_ten = Messages.objects.filter(since=since).order_by('-id')[:10]
last_ten_in_ascending_order = reversed(last_ten)

Solution 2:

Or use [::-1] instead of reversed:

last_ten = Messages.objects.filter(since=since).order_by('-id')[:10][::-1]

@ron_g:

Above solution uses list comprehension twice (first to slice to 10, then to reverse). You can do it as one operation, it's 9x faster.

last_ten = Messages.objects.filter(since=since).order_by('-id')[:10:-1]