#27065: Deferred fields not passed to inherited models' __class__.__dict__
-------------------------------------+-------------------------------------
Reporter: jarekwg | Owner: nobody
Type: Bug | Status: closed
Component: Database layer | Version: 1.10
(models, ORM) |
Severity: Normal | Resolution: invalid
Keywords: defer only | Triage Stage:
inherited DeferredAttribute | Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Changes (by jarekwg):
* keywords: defer inherited => defer only inherited DeferredAttribute
* status: new => closed
* resolution: => invalid
Comment:
Thanks, I've verified it's definitely commit
7f51876f99851fdc3fef63aecdfbcffa199c26b9 that causes this change in
behaviour.
`DeferredAttribute` instances inherited from parent models can no longer
be obtained through `instance.__class__.__dict__` because the class is
[https://github.com/django/django/commit/7f51876f99851fdc3fef63aecdfbcffa199c26b9
#diff-1e7fc0d7d1b36358e371fab97bd1ddb1L236 no longer dynamically created],
but rather has the `DeferredAttribute` instances
[https://github.com/django/django/commit/7f51876f99851fdc3fef63aecdfbcffa199c26b9
#diff-bf776a3b8e5dbfac2432015825ef8afeR695 stapled on] with `setattr`.
However, thanks to
[https://github.com/django/django/commit/7f51876f99851fdc3fef63aecdfbcffa199c26b9
#diff-1e7fc0d7d1b36358e371fab97bd1ddb1R99 this change], a handle to the
`DeferredAttribute` can be obtained by accessing the field directly from
the instance's class, which looks considerably nicer and ''does'' pull
through inherited fields.
So
`deffered_field = instance.__class__.__dict__.get(field_name) # pre
dj110`
becomes
`deferred_field = getattr(instance.__class__, field_name) # dj110+`
I guess it can't hurt mentioning this in the release notes, though at the
same time I don't see particularly many projects that would need to handle
the `DeferredAttributes` directly. You're in a better position to make
that call. At the very least this ticket can serve as an answer to people
who google this problem.
Closing.
--
Ticket URL: <https://code.djangoproject.com/ticket/27065#comment:2>
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