[Django] #22872: Backwards incompatible change: Can't proxy User model: RuntimeError: App registry isn't ready yet.
Django
registry isn't ready yet.
-------------------------------+------------------------
Reporter: jdufresne | Owner: nobody
Type: Bug | Status: new
Component: Uncategorized | Version: 1.7-beta-2
Severity: Normal | Keywords:
Triage Stage: Unreviewed | Has patch: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------+------------------------
My application creates proxies of the user model to add custom methods
that are useful in certain contexts. There is an attempt to do this in a
`AUTH_USER_MODEL` agnostic way. This fails with the latest beta version of
1.7.
Starting from a fresh install and project I created the following files in
directory `myapp`.
`myapp/models.py`
{{{
from django.contrib.auth import get_user_model
class MyUser(get_user_model()):
def my_method(self):
return 'foo'
class Meta:
proxy = True
}}}
`myapp/tests.py`
{{{
from django.test import TestCase
from myapp.models import MyUser
class MyTestCase(TestCase):
def test_my_user(self):
user = MyUser()
self.assertTrue(user)
}}}
Django 1.7 beta 2
{{{
$ python manage.py test
Traceback (most recent call last):
File "manage.py", line 10, in <module>
execute_from_command_line(sys.argv)
File "/home/jon/djtest/venv/lib/python2.7/site-
packages/django/core/management/__init__.py", line 427, in
execute_from_command_line
utility.execute()
File "/home/jon/djtest/venv/lib/python2.7/site-
packages/django/core/management/__init__.py", line 391, in execute
django.setup()
File "/home/jon/djtest/venv/lib/python2.7/site-
packages/django/__init__.py", line 21, in setup
apps.populate(settings.INSTALLED_APPS)
File "/home/jon/djtest/venv/lib/python2.7/site-
packages/django/apps/registry.py", line 106, in populate
app_config.import_models(all_models)
File "/home/jon/djtest/venv/lib/python2.7/site-
packages/django/apps/config.py", line 190, in import_models
self.models_module = import_module(models_module_name)
File "/usr/lib64/python2.7/importlib/__init__.py", line 37, in
import_module
__import__(name)
File "/home/jon/djtest/djtest/myapp/models.py", line 4, in <module>
class MyUser(get_user_model()):
File "/home/jon/djtest/venv/lib/python2.7/site-
packages/django/contrib/auth/__init__.py", line 136, in get_user_model
return django_apps.get_model(settings.AUTH_USER_MODEL)
File "/home/jon/djtest/venv/lib/python2.7/site-
packages/django/apps/registry.py", line 187, in get_model
self.check_ready()
File "/home/jon/djtest/venv/lib/python2.7/site-
packages/django/apps/registry.py", line 119, in check_ready
raise RuntimeError("App registry isn't ready yet.")
RuntimeError: App registry isn't ready yet.
}}}
Django 1.6.5
{{{
$ python manage.py test
Creating test database for alias 'default'...
.
----------------------------------------------------------------------
Ran 1 test in 0.001s
OK
Destroying test database for alias 'default'...
}}}
If there is a better (or forward compatible) way proxy an unknown `User`
model, I'd be happy to hear about it.
--
Ticket URL: <https://code.djangoproject.com/ticket/22872>
Django <https://code.djangoproject.com/>
The Web framework for perfectionists with deadlines.
Django
registry isn't ready yet.
Reporter: jdufresne | Owner: nobody
Type: Bug | Status: new
Component: Uncategorized | Version: 1.7-beta-2
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:
As part of the app-loading refactor, it's expected that calling
get_user_model() at compile-time fail with this message.
The best idea I have is to create an AppConfig for your app and create the
model in its ready() method, then add it to the module.
I suspect that many non-declarative models will require this pattern.
I'm leaving the ticket open for now in case someone has other ideas which
may involve changes in Django.
--
Ticket URL: <https://code.djangoproject.com/ticket/22872#comment:1>
Django
registry isn't ready yet.
Reporter: jdufresne | Owner: nobody
Type: Bug | Status: new
Component: Uncategorized | Version: 1.7-beta-2
Keywords: | Triage Stage: Unreviewed
Has patch: 0 | Needs documentation: 0
Easy pickings: 0 | UI/UX: 0
Comment (by jdufresne):
Replying to [comment:1 aaugustin]:
> The best idea I have is to create an AppConfig for your app and create
the model in its ready() method, then add it to the module.
How would one go about importing this model for use elsewhere (other
models, forms, views, etc.)? These references are often used at compile
time such as model forms and generic views. It seems, importing the proxy
model would never work at compile time. Every function that referenced the
proxy model directly would need to import it at the top of the function so
as to delay the import. Or, I guess, implement another `get_user_model()`
style function and sprinkle it all over.
--
Ticket URL: <https://code.djangoproject.com/ticket/22872#comment:2>
Django
registry isn't ready yet.
Reporter: jdufresne | Owner: nobody
Type: Bug | Status: new
Component: Uncategorized | Version: 1.7-beta-2
Keywords: | Triage Stage: Unreviewed
Has patch: 0 | Needs documentation: 0
Easy pickings: 0 | UI/UX: 0
Comment (by aaugustin):
Indeed, my suggestion doesn't work.
Replying to [comment:2 jdufresne]:
> Or, I guess, implement another `get_user_model()` style function and
sprinkle it all over.
I'm not sure that helps, because you still need to resolve the model at
compile time.
The only thing that works at compile time currently is
settings.AUTH_USER_MODEL. It can be used a an FK target because Django
specifically delays resolution of FKs until the target model is imported
(search for `class_prepared` in the code).
--
Ticket URL: <https://code.djangoproject.com/ticket/22872#comment:3>
Django
registry isn't ready yet.
Reporter: jdufresne | Owner: nobody
Type: | Status: new
Cleanup/optimization | Version:
Component: Documentation | 1.7-beta-2
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Easy pickings: 0 | UI/UX: 0
Changes (by timo):
* cc: app-loading (added)
* component: Uncategorized => Documentation
* type: Bug => Cleanup/optimization
* stage: Unreviewed => Accepted
Comment:
I guess we can accept this as a documentation improvement?
--
Ticket URL: <https://code.djangoproject.com/ticket/22872#comment:4>
Django
registry isn't ready yet.
Reporter: jdufresne | Owner: nobody
Type: | Status: new
Cleanup/optimization | Version:
Component: Documentation | 1.7-beta-2
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Easy pickings: 0 | UI/UX: 0
Comment (by wizpig64):
I also have an app that uses a user proxy (also with `class
MyUser(get_user_model()):`), which i'm porting up to 1.7. Looking through
the docs it seemed like using `apps.get_model('app.model')` (equivalent to
`apps.get_model('app', 'model')`) was they way to go about proxying to the
user model:
{{{
from django.apps import apps
from django.conf import settings
class MyUser(apps.get_model(settings.AUTH_USER_MODEL)):
class Meta:
proxy = True
}}}
but this raises "django.core.exceptions.AppRegistryNotReady: Models aren't
loaded yet."
It looks like this can be worked around by using the longer
`apps.get_app_config('app').get_model('model')`. I'm not sure if this is
intended behavior or a bug:
{{{
user_app, user_model = settings.AUTH_USER_MODEL.split('.')
class MyUser(apps.get_app_config(user_app).get_model(user_model)):
...
}}}
Some caveats: this only works if your model is after the base user model
in `INSTALLED_APPS`, and as long as `AUTH_USER_MODEL` only has one dot.
I suppose circumvents the whole point of the new app system, so that plus
the caveats probably makes it a bad idea to use. Rather than the above, I
think a new `get_user_model()` should be made, or a more clear way of
doing this should be documented.
The above stuff was tested on 1.7c2 and the latest stable/1.7.x as of
writing, http://github.com/django/django/commit/0f44d9f9b1. - I also
haven't checked any of the implications of this with migrations.
Thanks
--
Ticket URL: <https://code.djangoproject.com/ticket/22872#comment:5>
Django
registry isn't ready yet.
Reporter: jdufresne | Owner: nobody
Type: Cleanup/optimization | Status: new
Component: Documentation | Version: 1.7
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Easy pickings: 0 | UI/UX: 0
Changes (by timgraham):
* version: 1.7-beta-2 => 1.7
--
Ticket URL: <https://code.djangoproject.com/ticket/22872#comment:6>
Django
registry isn't ready yet.
Reporter: jdufresne | Owner: nobody
Type: Cleanup/optimization | Status: new
Component: Documentation | Version: 1.7
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Easy pickings: 0 | UI/UX: 0
Comment (by timgraham):
I noticed some ugly code in [https://github.com/divio/django-
cms/pull/3830/files django-cms] to work around this issue. That code is
currently inspecting `apps.all_models` to get the user model before the
apps registry is ready.
It seems to me as long as the application declaring the custom user model
appears in `INSTALLED_APPS` before the application that calls
`get_user_model()` there shouldn't be a problem with this technique. Am I
wrong?
--
Ticket URL: <https://code.djangoproject.com/ticket/22872#comment:7>
Django
registry isn't ready yet.
Reporter: jdufresne | Owner: nobody
Type: Cleanup/optimization | Status: new
Component: Documentation | Version: 1.7
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Easy pickings: 0 | UI/UX: 0
Comment (by aaugustin):
During the app-loading refactor, we agreed that we didn't want to
introduce constraints on the ordering of `INSTALLED_APPS` other than
precedence for finding templates, translations, etc. Otherwise you could
very quickly end up with a set of incompatible contraints.
I'm -1 on making the ability to import models conditional on a properly
ordered INSTALLED_APPS. Debugging import loops during models loading is
bad enough already (albeit better since 1.7).
If you want to get the user model anyway, `apps.all_models` or
`apps.get_registered_model` both "work", in the sense that they'll find
the model if it was already registered. The latter looks more like an API
than the former but there's a ticket about removing it.
--
Ticket URL: <https://code.djangoproject.com/ticket/22872#comment:8>
Django
registry isn't ready yet.
Reporter: jdufresne | Owner: nobody
Type: Cleanup/optimization | Status: new
Component: Documentation | Version: 1.7
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Easy pickings: 0 | UI/UX: 0
Comment (by aaugustin):
One solution may be to introduce the equivalent of [https://github.com
/django-oscar/django-oscar/blob/1.0/oscar/core/loading.py#L310-L340
django-oscar's get_model() function] and change get_user_model() to use
it.
I don't think it reintroduces any of the problems app-loading eliminated,
although that's hard to prove.
--
Ticket URL: <https://code.djangoproject.com/ticket/22872#comment:9>
Django
registry isn't ready yet.
Reporter: jdufresne | Owner: nobody
Type: Cleanup/optimization | Status: new
Component: Documentation | Version: 1.7
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Easy pickings: 0 | UI/UX: 0
Comment (by charettes):
The introduction of an equivalent shim look reasonable. Do you have an API
in mind?
--
Ticket URL: <https://code.djangoproject.com/ticket/22872#comment:10>
Django
registry isn't ready yet.
Reporter: jdufresne | Owner: nobody
Type: Cleanup/optimization | Status: new
Component: Documentation | Version: 1.7
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Easy pickings: 0 | UI/UX: 0
Comment (by ivanvenosdel):
I feel like this breaking change should have been added to the Django 1.7,
1.8 and 1.9 breaking changes section. Is it too late for that?
--
Ticket URL: <https://code.djangoproject.com/ticket/22872#comment:11>
Django
registry isn't ready yet.
Reporter: jdufresne | Owner: nobody
Type: Cleanup/optimization | Status: new
Component: Documentation | Version: 1.7
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Easy pickings: 0 | UI/UX: 0
Comment (by timgraham):
No, feel free to submit a patch. It would only be added to the 1.7 release
notes, not all subsequent versions.
--
Ticket URL: <https://code.djangoproject.com/ticket/22872#comment:12>
Django
registry isn't ready yet.
Reporter: jdufresne | Owner: nobody
Type: Cleanup/optimization | Status: new
Component: Documentation | Version: 1.7
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Easy pickings: 0 | UI/UX: 0
Comment (by ivanvenosdel):
Replying to [comment:12 timgraham]:
> No, feel free to submit a patch. It would only be added to the 1.7
release notes, not all subsequent versions.
Done
--
Ticket URL: <https://code.djangoproject.com/ticket/22872#comment:13>
Django
registry isn't ready yet.
Reporter: Jon Dufresne | Owner: nobody
Type: Cleanup/optimization | Status: closed
Component: Documentation | Version: 1.7
Severity: Normal | Resolution: wontfix
Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Easy pickings: 0 | UI/UX: 0
Changes (by Tim Graham):
* status: new => closed
* resolution: => wontfix
Comment:
Closing since 1.7 is old and no one has bothered to write a patch for the
release notes. #25966 is for allowing using `get_user_model()` at the
module level.
--
Ticket URL: <https://code.djangoproject.com/ticket/22872#comment:14>