#32524: unexpected behavior when using gettattr for related object
-------------------------------------+-------------------------------------
Reporter: elonzh | Owner: nobody
Type: Bug | Status: new
Component: Database | Version: 3.1
layer (models, ORM) |
Severity: Normal | Keywords:
Triage Stage: | Has patch: 0
Unreviewed |
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
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Assuming we have a model like that:
{{{
class UserProfile(models.Model):
user = models.OneToOneField(User, related_name="profile",
on_delete=models.CASCADE)
...
}}}
An user may not have an UserProfile instance so we will use such logic:
{{{
profile = getattr(request.user, "profile", UserProfile(user=request.user))
}}}
But django will always return the default value no matter
`request.user.profile` exists or not.
Here is the poc:
{{{
In [1]: u = User.objects.get(username='s')
In [2]: u.profile
Out[2]: <UserProfile: UserProfile object (5)>
In [3]: getattr(u, 'profile', UserProfile())
Out[3]: <UserProfile: UserProfile object (5)>
In [4]: getattr(u, 'profile', UserProfile(user=u))
Out[4]: <UserProfile: UserProfile object (None)>
}}}
the problem is `UserProfile(user=u)` will update the `User.profile` when
we init `UserProfile`.
--
Ticket URL: <https://code.djangoproject.com/ticket/32524>
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