[Django] #33207: django.apps.apps.get_model shortcut does not allow namespaced (PEP 420) apps to get a model
Django
apps to get a model
-----------------------------------------+------------------------
Reporter: Jonas L. | Owner: nobody
Type: Bug | Status: new
Component: Uncategorized | Version: 3.2
Severity: Normal | Keywords:
Triage Stage: Unreviewed | Has patch: 0
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
-----------------------------------------+------------------------
The '''django.contrib.auth''' app use '''django.apps.apps.get_model''' to
load the '''AUTH_USER_MODEL''' from the settings. While doing so it
leverage the shortcut to provide the ''app_name.ModelName'''.
The shortcut does not take into count that app_name can be a namespaced
(PEP 420) app like '''my_namespace.my_app''', and that we might want to
load a model from '''my_namespace.my_app.User'''.
This result in the following error:
{{{
Traceback (most recent call last):
File "/usr/local/lib/python3.7/dist-packages/django/db/models/utils.py",
line 15, in make_model_tuple
app_label, model_name = model.split(".")
ValueError: too many values to unpack (expected 2)
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "/usr/local/bin/libretime-api", line 10, in <module>
sys.exit(main())
File "/usr/local/lib/python3.7/dist-packages/libretime/api/cli.py", line
18, in main
execute_from_command_line(sys.argv)
File "/usr/local/lib/python3.7/dist-
packages/django/core/management/__init__.py", line 419, in
execute_from_command_line
utility.execute()
File "/usr/local/lib/python3.7/dist-
packages/django/core/management/__init__.py", line 395, in execute
django.setup()
File "/usr/local/lib/python3.7/dist-packages/django/__init__.py", line
24, in setup
apps.populate(settings.INSTALLED_APPS)
File "/usr/local/lib/python3.7/dist-packages/django/apps/registry.py",
line 114, in populate
app_config.import_models()
File "/usr/local/lib/python3.7/dist-packages/django/apps/config.py",
line 301, in import_models
self.models_module = import_module(models_module_name)
File "/usr/lib/python3.7/importlib/__init__.py", line 127, in
import_module
return _bootstrap._gcd_import(name[level:], package, level)
File "<frozen importlib._bootstrap>", line 1006, in _gcd_import
File "<frozen importlib._bootstrap>", line 983, in _find_and_load
File "<frozen importlib._bootstrap>", line 967, in
_find_and_load_unlocked
File "<frozen importlib._bootstrap>", line 677, in _load_unlocked
File "<frozen importlib._bootstrap_external>", line 728, in exec_module
File "<frozen importlib._bootstrap>", line 219, in
_call_with_frames_removed
File "/usr/local/lib/python3.7/dist-
packages/django/contrib/admin/models.py", line 39, in <module>
class LogEntry(models.Model):
File "/usr/local/lib/python3.7/dist-packages/django/db/models/base.py",
line 161, in __new__
new_class.add_to_class(obj_name, obj)
File "/usr/local/lib/python3.7/dist-packages/django/db/models/base.py",
line 326, in add_to_class
value.contribute_to_class(cls, name)
File "/usr/local/lib/python3.7/dist-
packages/django/db/models/fields/related.py", line 747, in
contribute_to_class
super().contribute_to_class(cls, name, private_only=private_only,
**kwargs)
File "/usr/local/lib/python3.7/dist-
packages/django/db/models/fields/related.py", line 318, in
contribute_to_class
lazy_related_operation(resolve_related_class, cls,
self.remote_field.model, field=self)
File "/usr/local/lib/python3.7/dist-
packages/django/db/models/fields/related.py", line 80, in
lazy_related_operation
return apps.lazy_model_operation(partial(function, **kwargs),
*model_keys)
File "/usr/local/lib/python3.7/dist-
packages/django/db/models/fields/related.py", line 78, in <genexpr>
model_keys = (make_model_tuple(m) for m in models)
File "/usr/local/lib/python3.7/dist-packages/django/db/models/utils.py",
line 24, in make_model_tuple
"must be of the form 'app_label.ModelName'." % model
ValueError: Invalid model reference 'libretime.api.User'. String model
references must be of the form 'app_label.ModelName'.
}}}
Some links:
https://github.com/django/django/blob/e2f778d57947d168a875159e6df075255eea4bbc/django/contrib/auth/__init__.py#L160
https://docs.djangoproject.com/en/3.2/ref/applications/#django.apps.apps.get_model
--
Ticket URL: <https://code.djangoproject.com/ticket/33207>
Django <https://code.djangoproject.com/>
The Web framework for perfectionists with deadlines.
Django
get a model
------------------------------+--------------------------------------
Reporter: Jonas L. | Owner: nobody
Component: Core (Other) | Version: 3.2
Severity: Normal | Resolution: invalid
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 Mariusz Felisiak):
* status: new => closed
* resolution: => invalid
* component: Uncategorized => Core (Other)
Comment:
Thanks for the ticket, however Django doesn't support namespace packages,
see [https://groups.google.com/g/django-
developers/c/GVHMH2ciAnk/m/vbIPbZuSBQAJ a discussion on the mailing list].
It's also
[https://docs.djangoproject.com/en/stable/topics/auth/customizing/#substituting-a
-custom-user-model documented] that `AUTH_USER_MODEL` is ''"dotted pair
describes the name of the Django app ... and the name of the Django model
that you wish to use as your user model"''.
--
Ticket URL: <https://code.djangoproject.com/ticket/33207#comment:1>
Django
get a model
------------------------------+--------------------------------------
Reporter: Jonas L. | Owner: nobody
Component: Core (Other) | Version: 3.2
Severity: Normal | Resolution: invalid
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
Comment (by Jonas L.):
Replying to [comment:1 Mariusz Felisiak]:
> Thanks for the ticket, however Django doesn't support namespace
packages, see [https://groups.google.com/g/django-
developers/c/GVHMH2ciAnk/m/vbIPbZuSBQAJ a discussion on the mailing list].
It's also
[https://docs.djangoproject.com/en/stable/topics/auth/customizing/#substituting-a
-custom-user-model documented] that `AUTH_USER_MODEL` is ''"dotted pair
describes the name of the Django app ... and the name of the Django model
that you wish to use as your user model"''.
In that case the following documentation is misleading
https://docs.djangoproject.com/en/3.2/ref/applications/#namespace-package
I understood that if I meet the requirements, using a namespace is
possible. Or maybe I didn't understand it right ?
--
Ticket URL: <https://code.djangoproject.com/ticket/33207#comment:2>
Django
get a model
------------------------------+--------------------------------------
Reporter: Jonas L. | Owner: nobody
Component: Core (Other) | Version: 3.2
Severity: Normal | Resolution: invalid
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
Comment (by Carlton Gibson):
PEP 420 is about being able to ''compose'' a package from code situated at
different locations on the filesystem. These are known as ''namespace
packages''.
There's a [https://www.python.org/dev/peps/pep-0420/#nested-namespace-
packages Nested namespace packages example] but it's not really about
''namespaces',' as in nesting that you get from folders, that we're
familiar with from ''Namespaces are one honking great idea -- let's do
more of those!''
--
Ticket URL: <https://code.djangoproject.com/ticket/33207#comment:3>
Django
get a model
------------------------------+--------------------------------------
Reporter: Jonas L. | Owner: nobody
Component: Core (Other) | Version: 3.2
Severity: Normal | Resolution: invalid
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
Comment (by Jonas L.):
> There's a Nested namespace packages example but it's not really about
namespaces',' as in nesting that you get from folders, that we're familiar
with from Namespaces are one honking great idea -- let's do more of
those''
Sorry, I am not sure I understand your comment here.
I probably didn't explain enough my use case.
We have few services, '''playout''', '''analyzer''', '''api''', and more.
Only one of them is actually based on Django the '''api'''.
Our goal is to put them into the libretime namespace so we don't collide
with other packages/modules. This would result in '''libretime.playout''',
'''libretime.analyzer''', '''libretime.api'''.
The django app is still full of __init__.py files, we just wanted to wrap
it into the namespace so we can separate the different services.
I understood the documentation like this: "Since our django app does not
have anything anything outside the '''libretime/api''' folder, we can put
it in the libretime namespace.
So based on my explanation, is it doable ? And how can we make the
documentation less misleading, as it seem to perfectly fit my uses case ?
Thanks for your time, and sorry if I have trouble to understand your
answers, the question was probably too short.
--
Ticket URL: <https://code.djangoproject.com/ticket/33207#comment:4>
Django
get a model
------------------------------+--------------------------------------
Reporter: Jonas L. | Owner: nobody
Component: Core (Other) | Version: 3.2
Severity: Normal | Resolution: invalid
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
Comment (by Jonas L.):
Oooh, first let me apologize for not noticing the different between an
App.name and an App.label.
I guess I could fix my issue by using a custom App.label, without dot.
My app now looks like this:
{{{
from pathlib import Path
from django.apps import AppConfig
here = Path(__file__).parent
class LibreTimeAPIConfig(AppConfig):
name = "libretime.api"
label = "libretime_api"
path = here
verbose_name = "LibreTime API"
default_auto_field = "django.db.models.AutoField"
}}}
And it seem to be working.
Sorry again for this new comer error.
--
Ticket URL: <https://code.djangoproject.com/ticket/33207#comment:5>
Django
get a model
------------------------------+--------------------------------------
Reporter: Jonas L. | Owner: nobody
Component: Core (Other) | Version: 3.2
Severity: Normal | Resolution: invalid
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
Comment (by Mariusz Felisiak):
Replying to [comment:5 Jonas L.]:
> Oooh, first let me apologize for not noticing the different between an
App.name and an App.label.
>
> I guess I could fix my issue by using a custom App.label, without dot.
Yes, I proposed a small clarification, see
[https://github.com/django/django/pull/15006 PR].
--
Ticket URL: <https://code.djangoproject.com/ticket/33207#comment:6>
Django
get a model
------------------------------+--------------------------------------
Reporter: Jonas L. | Owner: nobody
Component: Core (Other) | Version: 3.2
Severity: Normal | Resolution: invalid
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
Comment (by GitHub <noreply@…>):
In [changeset:"fd881e8cd9b7686ab8fcd32332100710a8ffaa10" fd881e8c]:
{{{
#!CommitTicketReference repository=""
revision="fd881e8cd9b7686ab8fcd32332100710a8ffaa10"
Refs #33207 -- Clarified that AUTH_USER_MODEL expects an app label.
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/33207#comment:7>
Django
get a model
------------------------------+--------------------------------------
Reporter: Jonas L. | Owner: nobody
Component: Core (Other) | Version: 3.2
Severity: Normal | Resolution: invalid
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
Comment (by Mariusz Felisiak <felisiak.mariusz@…>):
In [changeset:"ea66d1f2ae0053ddbb0c9e0f725dd78cbf70a249" ea66d1f2]:
{{{
#!CommitTicketReference repository=""
revision="ea66d1f2ae0053ddbb0c9e0f725dd78cbf70a249"
[4.0.x] Refs #33207 -- Clarified that AUTH_USER_MODEL expects an app
label.
Backport of fd881e8cd9b7686ab8fcd32332100710a8ffaa10 from main
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/33207#comment:8>