#16563: Error pickling request.user
---------------------------------+------------------------------------
Reporter: zero.fuxor@… | Owner: nobody
Type: Bug | Status: new
Component: contrib.auth | Version: 1.3
Severity: Release blocker | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
---------------------------------+------------------------------------
Comment (by lukeplant):
OK, this has turned out to be rather tricky.
The previous patch only works for objects that have no state. The basic
problem is that due to proxying the `__class__` attribute, the pickling
machinery is confused (I think), and so it stores a reference to the class
of the wrapped object, rather than `SimpleLazyObject`.
So, we need to define the `__reduce__` method for full customization,
rather than the simpler `__getstate__` method. However, for some reason,
the presence of the `__class__` attribute proxying causes this to fail -
if you define `__reduce__` on `SimpleLazyObject`, it is never called when
pickling unless you remove the `__class__` hacking.
This takes us back to using `__getstate__` (which, for some reason,
doesn't suffer from the same problem as `__reduce__`). But now we have to
cooperate with the fact that pickling will skip `SimpleLazyObject` and
store a reference to the wrapped class, and define `__getstate__` so that
it returns the state from the wrapped object. This appears to work:
{{{
#!python
def __getstate__(self):
if self._wrapped is empty:
self._setup()
return self._wrapped.__dict__
}}}
The result is that on unpickling, the `SimpleLazyObject` wrapper
disappears entirely, which should be OK.
I still get failure if `SimpleLazyObject` is wrapping a builtin, and
nothing but removing the `__class__` proxying appears to be able to fix
that. But that bug has always been there, and this change doesn't affect
it.
I've confirmed that with this patch you can pickle `request.user`, and on
pickling get an object that compares equal to the original, so I'm
therefore committing my improved patch.
--
Ticket URL: <https://code.djangoproject.com/ticket/16563#comment:21>
Django <https://code.djangoproject.com/>
The Web framework for perfectionists with deadlines.
--
You received this message because you are subscribed to the Google Groups
"Django updates" group.
To post to this group, send email to [email protected].
To unsubscribe from this group, send email to
[email protected].
For more options, visit this group at
http://groups.google.com/group/django-updates?hl=en.
