#23370: defer() with inherited models fails
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Reporter: dfunckt | Owner: nobody
Type: Bug | Status: new
Component: Database layer (models, ORM) | Version: master
Severity: Normal | Keywords:
Triage Stage: Unreviewed | Has patch: 0
Easy pickings: 0 | UI/UX: 0
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Let's say I have two models: {{{Post(models.Model)}}} and
{{{Article(Post)}}} and some data.
Now if I evaluate the query set
{{{Post.objects.select_related('article').defer('article__somefield')}}}
it will fail with:
{{{
...
File "django/db/models/query.py", line 1457, in get_cached_row
if (fields[pk_idx] is None or
IndexError: tuple index out of range
}}}
This prevents us from using {{{defer()}}} to optimise our queries to defer
loading of large TEXT fields when showing lists of posts.
This is present in master [a81af7f49de7ff3f51f111de28ed3a682f67ea89] and
(with a similar traceback) since at least Django 1.6.
I have attached a test project that demonstrates the bug. Add the project
to path and run:
{{{
$ ./manage.py migrate
$ ./manage.py testdefer
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/23370>
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