#26977: TypeError: isinstance() arg 2 must be a class, type, or tuple of classes
and types
--------------------------------------+--------------------
Reporter: teeberg | Owner: nobody
Type: Cleanup/optimization | Status: new
Component: Uncategorized | Version: 1.9
Severity: Normal | Keywords:
Triage Stage: Unreviewed | Has patch: 0
Easy pickings: 0 | UI/UX: 0
--------------------------------------+--------------------
Trying to instantiate an abstract model with a foreign key worked without
throwing any warnings in Django 1.8. In Django 1.9.8, this code:
{{{
class UserProfile(Model):
user = models.ForeignKey('auth.user')
class Meta(object):
app_label = 'core'
abstract = True
UserProfile()
}}}
raises this exception:
{{{
Traceback (most recent call last):
File "<ipython-input-7-5fa4dfdf1ad9>", line 2, in <module>
UserProfile()
File ".../.venv/lib/python2.7/site-packages/django/db/models/base.py",
line 432, in __init__
val = field.get_default()
File ".../.venv/lib/python2.7/site-
packages/django/db/models/fields/related.py", line 905, in get_default
if isinstance(field_default, self.remote_field.model):
TypeError: isinstance() arg 2 must be a class, type, or tuple of classes
and types
}}}
While the code mentions that abstract models can not be instantiated [1],
I couldn't find mention of this in the docs. Abstract models without
foreign keys can still be instantiated perfectly fine.
I couldn't find any description of this change in the Release Notes, so
not sure if I missed it there or if this is maybe an undocumented
backwards-incompatible change.
[1]
https://github.com/django/django/blob/026574e03c6b6fd20a45f97b0470afb70e41fda4/django/db/models/base.py#L284
--
Ticket URL: <https://code.djangoproject.com/ticket/26977>
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