#28806: Mechanism of fetching related objects violates READ COMMITTED
assumption of
Django ORM
-------------------------------------+-------------------------------------
Reporter: Aaron Tan | Owner: nobody
Type: Bug | Status: new
Component: Database layer | Version: master
(models, ORM) |
Severity: Normal | Resolution:
Keywords: database, read- | Triage Stage:
committed, concurrency control | Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Comment (by Tomer Chachamu):
The comment is definitely inaccurate, but I don't think the attribute
returning {{{None}}} is the right answer. Sure, the FK is set to NULL on
conflict, but maybe transaction B also updated
{{{Bar.objects.get(pk=<bar's pk>).pk}}} to a new value? In this case, A
will see the new value after a {{{bar.refresh_from_db()}}}, that is not
{{{None}}}.
The docs could probably be improved, to mention that you can use
{{{select_related}}} to prevent this {{{DoesNotExist}}} from being thrown.
(Although, it doesn't remove the fact that you will insert on save, when
you probably meant to update).
--
Ticket URL: <https://code.djangoproject.com/ticket/28806#comment:1>
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