#28723: RelatedManager.get_prefetch_queryset returns "wrong" cache_name
-------------------------------------+-------------------------------------
Reporter: Mike Hansen | Owner: nobody
Type: Uncategorized | Status: new
Component: Database layer | Version: master
(models, ORM) |
Severity: Normal | Resolution:
Keywords: | Triage Stage:
| Unreviewed
Has patch: 1 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
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Description changed by Mike Hansen:
Old description:
> Currently, `RelatedManager.get_prefetch_queryset` returns
> `self.field.related_query_name()` as the `cache_name`. In the case where
> no `related_name` has been set on the `ForeignKey`, then this does not
> match with the `through_attr` used by `get_prefetcher`.
>
> Using the models in `tests/prefetch_related/models.py`,
>
> {{{#!python
> BookWithYear.objects.prefetch_related('bookreview_set')
> }}}
> will use a `through_attr` of `bookreview_set`, but `bookreview` is what
> will be placed in `_prefetched_objects_cache`.
>
> I think `related_manager.field.remote_field.get_accessor_name()` should
> be used instead.
>
> I'll post a patch fixing this and adding a test case.
New description:
Currently, `RelatedManager.get_prefetch_queryset` returns
`self.field.related_query_name()` as the `cache_name`. In the case where
no `related_name` has been set on the `ForeignKey`, then this does not
match with the `through_attr` used by `get_prefetcher`.
Using the models in `tests/prefetch_related/models.py`,
{{{#!python
BookWithYear.objects.prefetch_related('bookreview_set')
}}}
will use a `through_attr` of `"bookreview_set"`, but `"bookreview"` is
what will be placed in `_prefetched_objects_cache`.
I think `related_manager.field.remote_field.get_accessor_name()` should be
used instead.
I'll post a patch fixing this and adding a test case.
--
--
Ticket URL: <https://code.djangoproject.com/ticket/28723#comment:2>
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