#20923: Unable to use fields from prefetch_related() in only() and defer()
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Reporter: alexpirine | Owner: nobody
Type: New feature | Status: closed
Component: Database layer | Version: 1.5
(models, ORM) | Resolution: wontfix
Severity: Normal | Triage Stage:
Keywords: defer only | Unreviewed
ForeignKey reverse relationship | Needs documentation: 0
Has patch: 0 | Patch needs improvement: 0
Needs tests: 0 | UI/UX: 0
Easy pickings: 0 |
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Comment (by alexpirine):
Replying to [comment:3 akaariai]:
> I think a better way is to add custom query support to prefetch_related
(or, #17001). Main reason is that I believe implementation of
communicating the only/defer data from the main query to the prefetch
queries will be hard to do cleanly.
Thanks, it looks interesting. If I understood it correctly, I could pass
the only() attribute to the custom queryset:
{{{
ParentModel.objects.prefetch_related(
R('child_model', to_attr = 'childs', qs =
ChildModel.objects.only('child_attribute')
).only('parent_attribute').all()
}}}
which would answer this issue.
--
Ticket URL: <https://code.djangoproject.com/ticket/20923#comment:5>
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