[Django] #25477: Modelbase.__new__ causes `AppRegistryNotReady`
Django
---------------------------------+--------------------
Reporter: cdestigter | Owner: nobody
Type: Bug | Status: new
Component: Core (Other) | Version: 1.9a1
Severity: Release blocker | Keywords:
Triage Stage: Unreviewed | Has patch: 0
Easy pickings: 0 | UI/UX: 0
---------------------------------+--------------------
I'm probably missing something, but I've noticed a regression when testing
1.9.
My standalone app django-typed-models gets this stack trace on django
1.9a1:
{{{#!python
Traceback (most recent call last):
File "./runtests.py", line 12, in <module>
django.setup()
File ".../site-packages/django/__init__.py", line 18, in setup
apps.populate(settings.INSTALLED_APPS)
File ".../site-packages/django/apps/registry.py", line 85, in populate
app_config = AppConfig.create(entry)
File ".../site-packages/django/apps/config.py", line 90, in create
module = import_module(entry)
File
"/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/importlib/__init__.py",
line 37, in import_module
__import__(name)
File "./typedmodels/__init__.py", line 2, in <module>
from .models import TypedModel
File "./typedmodels/models.py", line 301, in <module>
class TypedModel(with_metaclass(TypedModelMetaclass, models.Model)):
File ".../site-packages/django/utils/six.py", line 778, in __new__
return meta(name, bases, d)
File "./typedmodels/models.py", line 49, in __new__
typed_model = super(TypedModelMetaclass, meta).__new__(meta,
classname, bases, classdict)
File ".../site-packages/django/db/models/base.py", line 94, in __new__
app_config = apps.get_containing_app_config(module)
File ".../site-packages/django/apps/registry.py", line 239, in
get_containing_app_config
self.check_apps_ready()
File ".../site-packages/django/apps/registry.py", line 124, in
check_apps_ready
raise AppRegistryNotReady("Apps aren't loaded yet.")
django.core.exceptions.AppRegistryNotReady: Apps aren't loaded yet.
}}}
It looks like `ModelBase.__new__` is calling
`apps.get_containing_app_config`, and that calls `check_apps_ready` which
throws the exception.
But, AFAICT the app-loading process imports the models, so it seems
obvious that the apps aren't ever ready when the models are being defined.
It seems if I remove [https://github.com/craigds/django-typed-
models/blob/master/typedmodels/__init__.py#L2 this line] from my app, the
problem goes away.
I'm hesitant to do that because it'd be backwards-incompatible for users
of my app (and `from typedmodels import TypedModel` is much less
repetitive than `from typedmodels.models import TypedModel`)
If importing the models file from the `__init__.py` is really no longer
supported, perhaps a note should be added to the django 1.9 release notes
about it?
--
Ticket URL: <https://code.djangoproject.com/ticket/25477>
Django <https://code.djangoproject.com/>
The Web framework for perfectionists with deadlines.
Django
---------------------------------+--------------------------------------
Reporter: cdestigter | Owner: nobody
Type: Bug | Status: new
Component: Core (Other) | Version: 1.9a1
Keywords: | Triage Stage: Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
Changes (by aaugustin):
* needs_better_patch: => 0
* needs_tests: => 0
* needs_docs: => 0
Comment:
"Loading apps" means "importing the Python package containing each app". A
deprecation path was started in Django 1.7 to require that Django can
import apps before importing models so this is indeed no longer supported.
Please review the 1.7 release notes and make sure your code runs without
deprecation warnings on 1.8 before running it on 1.9. The 1.9 release
notes already point to the deprecation timeline where this change is
explained.
--
Ticket URL: <https://code.djangoproject.com/ticket/25477#comment:1>
Django
---------------------------------+--------------------------------------
Type: Bug | Status: new
Component: Core (Other) | Version: 1.9a1
Keywords: | Triage Stage: Unreviewed
Has patch: 0 | Needs documentation: 0
Easy pickings: 0 | UI/UX: 0
Comment (by cdestigter):
Thanks Aymeric
Unfortunately I don't see any warnings with Django 1.8. Could you quote
the relevant part of the 1.7 deprecation notes here? I might be being
thick, but I don't see anything that looks relevant at
https://docs.djangoproject.com/en/1.8/releases/1.7/#features-deprecated-
in-1-7
--
Ticket URL: <https://code.djangoproject.com/ticket/25477#comment:2>
Django
------------------------------+------------------------------------
Reporter: cdestigter | Owner: nobody
Type: Bug | Status: new
Component: Core (Other) | Version: 1.9a1
Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Easy pickings: 0 | UI/UX: 0
Changes (by aaugustin):
* severity: Release blocker => Normal
* stage: Unreviewed => Accepted
Comment:
From https://docs.djangoproject.com/en/1.7/internals/deprecation
/#deprecation-removed-in-1-9:
> Furthermore, it won’t be possible to import them before their
application is loaded. In particular, it won’t be possible to import
models inside the root package of their application.
That said, you have a point, this particular piece of information isn't
duplicated in the release notes, most likely because I didn't expect
anyone to do that.
Furthermore your code crashes just before the point where a warning should
have been raised previously. At first I expected
https://github.com/django/django/commit/1b8af4cfa023161924a45fb572399d2f3071bf5b
to cause the exception but in fact it occurs before the code changed in
this commit.
I must have messed up the backwards-compatibility checks at some point. If
you can bisect the commit that introduced this failure it would be very
helpful.
I'm downgrading severity because the only problem here is that lack of a
proper deprecation path.
--
Ticket URL: <https://code.djangoproject.com/ticket/25477#comment:3>
Django
------------------------------+------------------------------------
Type: Bug | Status: new
Component: Core (Other) | Version: 1.9a1
Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Easy pickings: 0 | UI/UX: 0
Comment (by cdestigter):
Apologies for the delay. I had a little baby girl in the meantime, so had
other things on my mind than this ticket :)
I tried to bisect the deprecation warning change, but I couldn't find any
deprecation warnings with any versions in 1.7.x or 1.8.x. (I did see other
unrelated deprecation warnings, so it's not that I had them turned off or
anything). In addition several django-internal methods have been altered
several times (`Model._meta` refactor) between 1.7 and 1.9 so it was too
confusing to bisect.
I've pushed django-typed-models 0.5.0 which works with django 1.9. Users
will just have to change their import path when upgrading.
--
Ticket URL: <https://code.djangoproject.com/ticket/25477#comment:4>
Django
------------------------------+------------------------------------
Type: Bug | Status: new
Component: Core (Other) | Version: 1.9
Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Easy pickings: 0 | UI/UX: 0
Changes (by timgraham):
* version: 1.9a1 => 1.9
Comment:
I'm not sure how to proceed with this ticket. The 1.7 release notes say
"Specifically, you shouldn't import models in the root module of an
application". What's the missing piece of information in the release
notes?
It doesn't seem very worthwhile to try to add deprecation warnings to 1.7
and/or 1.8 at this point.
--
Ticket URL: <https://code.djangoproject.com/ticket/25477#comment:5>
Django
------------------------------+------------------------------------
Type: Bug | Status: new
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Easy pickings: 0 | UI/UX: 0
Comment (by craigds):
Basically something that worked fine in 1.8 (with no deprecation warnings,
AFAICT) no longer works in 1.9, and there wasn't anything in the 1.9
release notes about it. So it was a difficult thing to figure out when
upgrading from 1.8 to 1.9.
You are correct that it was mentioned briefly in the deprecation section
of the 1.7 release notes.
If you don't think it's worth fixing the deprecation warnings for 1.7/1.8,
feel free to close the ticket.
--
Ticket URL: <https://code.djangoproject.com/ticket/25477#comment:6>
Django
------------------------------+------------------------------------
Type: Bug | Status: new
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Easy pickings: 0 | UI/UX: 0
Comment (by aaugustin):
Considering that 1.8 is a LTS release, I support adding an appropriate
deprecation warning there (if someone figures out how).
--
Ticket URL: <https://code.djangoproject.com/ticket/25477#comment:7>
Django
------------------------------+------------------------------------
Type: Bug | Status: new
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Easy pickings: 0 | UI/UX: 0
Comment (by edmorley):
This caused confusion for me too - particularly since googling the
exception (but not specifically django 1.9) brings up a number of
misleading fixes for older problems.
It would be great if:
* The deprecation warning could be fixed in Django 1.8, particularly since
it's an LTS release.
* The Django 1.9 release notes could emphasise this breakage a bit more
than they do currently, perhaps by changing this paragraph:
> All models need to be defined inside an installed application or declare
an explicit app_label. Furthermore, it isn’t possible to import them
before their application is loaded. In particular, it isn’t possible to
import models inside the root package of an application.
(https://docs.djangoproject.com/en/1.9/releases/1.9/#features-removed-
in-1-9)
...to mention the `AppRegistryNotReady: Apps aren't loaded yet.` exception
explicitly.
* The `AppRegistryNotReady` exception could state what app was being
loaded, since it's not always clear from the traceback. (And in my case it
was one of my third party packages that was causing the problem.)
Many thanks :-)
--
Ticket URL: <https://code.djangoproject.com/ticket/25477#comment:8>
Django
----------------------------------+------------------------------------
Reporter: Craig de Stigter | Owner: nobody
Type: Bug | Status: closed
Component: Core (Other) | Version: 1.9
Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Easy pickings: 0 | UI/UX: 0
Changes (by Baptiste Mispelon):
* status: new => closed
* resolution: => wontfix
Comment:
Considering that versions 1.8 is no longer supported, I don't see a reason
to keep this ticket open since it was accepted on the basis of adding
release notes and/or proper deprecation warnings for 1.8.
Feel free to reopen if I've missed something.
--
Ticket URL: <https://code.djangoproject.com/ticket/25477#comment:9>