> Den 16/09/2015 kl. 19.08 skrev Simon Charette <charett...@gmail.com>:
>
> If you want to use this approach I'm afraid you'll have to do
> what prefetch_related does under the hood by yourself.
>
> e.g.
>
> from collections import defaultdict
>
> prefetched = defaultdict(list)
> subjects = Subject.objects.filter(...)
> lessons = Lesson.objects.filter(...)
> for lesson_subject in
> Lesson.subjects.through.objects.filter(lesson__in=lessons,
> subject__in=subject).select_related('subject').iterator():
> prefetched[lesson_subject.lesson_id].append(lesson_subject.subject)
I hacked up a quick solution that works for my limited requirements. No chained
querysets, limited prefetch recursion, no order_by, extras etc. But maybe
someone finds it useful:
https://gist.github.com/ecederstrand/6748a3496acdc95e40ef
At least it speeds up my queries exponentially; 10-50x improvement in my tests
so far.
Erik
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