#26780: Prefetch objects don't work with slices
-------------------------------------+-------------------------------------
Reporter: ludwik | Owner: nobody
Type: New feature | Status: new
Component: Database layer | Version: master
(models, ORM) |
Severity: Normal | Resolution:
Keywords: prefetch, slicing | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Changes (by charettes):
* type: Bug => New feature
* version: 1.9 => master
* component: Uncategorized => Database layer (models, ORM)
* stage: Unreviewed => Accepted
Comment:
Tentatively accepting but as you've noticed it would require a large
refactor of the way prefetching is actually done.
I could see `Category.objects.prefetch_related(Prefetch('articles',
Article.object.order_by('-published_data')[0:3],
to_attr='latest_articles'))` being useful but the underlying prefetch
query would need to rely on subqueries, a feature the ORM is not good at
for now.
Maybe the addition of the [https://github.com/django/django/pull/6478
Subquery] expression could help here.
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Ticket URL: <https://code.djangoproject.com/ticket/26780#comment:5>
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