Type[SomeConcreteModel] has no attribute "objects" -- but it does at runtime

[asottile-sentry]

Bug report

unfortunately having a really hard time tracking this down -- I've seen #1684 already however this is a concrete model and not an abstract one

What's wrong

I haven't been able to narrow this to a minimal case so I suspect it's something wrong with our setup -- here's at least a maximal reproduction:

set -euxo pipefail

rm -rf sentry

git clone -qq --depth=1 https://github.com/getsentry/sentry -b 23.9.1 >& /dev/null
cd sentry
python3.8 -m venv venv >& /dev/null
# cheaty editable install so you don't need node
echo "$PWD/src" > venv/lib/python3.8/site-packages/easy-install.pth
venv/bin/pip install -qq --no-deps -r requirements-dev-frozen.txt
venv/bin/pip install -qq --upgrade mypy django-stubs django-stubs-ext
venv/bin/mypy tests/sentry/db/models/fields/test_jsonfield.py

output:

$ bash t.sh 
+ rm -rf sentry
+ git clone -qq --depth=1 https://github.com/getsentry/sentry -b 23.9.1
+ cd sentry
+ python3.8 -m venv venv
+ echo /tmp/y/sentry/src
+ venv/bin/pip install -qq --no-deps -r requirements-dev-frozen.txt
+ venv/bin/pip install -qq --upgrade mypy django-stubs django-stubs-ext
+ venv/bin/mypy tests/sentry/db/models/fields/test_jsonfield.py
tests/sentry/db/models/fields/test_jsonfield.py:58: error: "Type[JSONFieldTestModel]" has no attribute "objects"  [attr-defined]
tests/sentry/db/models/fields/test_jsonfield.py:64: error: "Type[JSONFieldTestModel]" has no attribute "objects"  [attr-defined]
tests/sentry/db/models/fields/test_jsonfield.py:68: error: "Type[JSONFieldTestModel]" has no attribute "objects"  [attr-defined]
tests/sentry/db/models/fields/test_jsonfield.py:69: error: "Type[JSONFieldTestModel]" has no attribute "objects"  [attr-defined]
tests/sentry/db/models/fields/test_jsonfield.py:119: error: "Type[JSONFieldWithDefaultTestModel]" has no attribute "objects"  [attr-defined]
tests/sentry/db/models/fields/test_jsonfield.py:120: error: "Type[JSONFieldWithDefaultTestModel]" has no attribute "objects"  [attr-defined]
tests/sentry/db/models/fields/test_jsonfield.py:124: error: "Type[JSONFieldTestModel]" has no attribute "objects"  [attr-defined]
tests/sentry/db/models/fields/test_jsonfield.py:125: error: "Type[JSONFieldTestModel]" has no attribute "objects"  [attr-defined]
tests/sentry/db/models/fields/test_jsonfield.py:126: error: "Type[JSONFieldTestModel]" has no attribute "objects"  [attr-defined]
tests/sentry/db/models/fields/test_jsonfield.py:127: error: "Type[JSONFieldTestModel]" has no attribute "objects"  [attr-defined]
tests/sentry/db/models/fields/test_jsonfield.py:128: error: "Type[JSONFieldTestModel]" has no attribute "objects"  [attr-defined]
tests/sentry/db/models/fields/test_jsonfield.py:129: error: "Type[JSONFieldTestModel]" has no attribute "objects"  [attr-defined]
tests/sentry/db/models/fields/test_jsonfield.py:131: error: "Type[JSONFieldTestModel]" has no attribute "objects"  [attr-defined]
tests/sentry/db/models/fields/test_jsonfield.py:133: error: "Type[JSONFieldTestModel]" has no attribute "objects"  [attr-defined]
tests/sentry/db/models/fields/test_jsonfield.py:135: error: "Type[JSONFieldTestModel]" has no attribute "objects"  [attr-defined]
tests/sentry/db/models/fields/test_jsonfield.py:139: error: "Type[JSONFieldTestModel]" has no attribute "objects"  [attr-defined]
tests/sentry/db/models/fields/test_jsonfield.py:142: error: "Type[JSONFieldTestModel]" has no attribute "objects"  [attr-defined]
tests/sentry/db/models/fields/test_jsonfield.py:146: error: "Type[JSONFieldTestModel]" has no attribute "objects"  [attr-defined]
tests/sentry/db/models/fields/test_jsonfield.py:147: error: "Type[JSONFieldTestModel]" has no attribute "objects"  [attr-defined]
tests/sentry/db/models/fields/test_jsonfield.py:148: error: "Type[JSONFieldTestModel]" has no attribute "objects"  [attr-defined]
tests/sentry/db/models/fields/test_jsonfield.py:150: error: "Type[JSONFieldTestModel]" has no attribute "objects"  [attr-defined]
tests/sentry/db/models/fields/test_jsonfield.py:151: error: "Type[JSONFieldTestModel]" has no attribute "objects"  [attr-defined]
tests/sentry/db/models/fields/test_jsonfield.py:154: error: "Type[BlankJSONFieldTestModel]" has no attribute "objects"  [attr-defined]
tests/sentry/db/models/fields/test_jsonfield.py:155: error: "Type[BlankJSONFieldTestModel]" has no attribute "objects"  [attr-defined]
tests/sentry/db/models/fields/test_jsonfield.py:159: error: "Type[BlankJSONFieldTestModel]" has no attribute "objects"  [attr-defined]
tests/sentry/db/models/fields/test_jsonfield.py:164: error: "Type[CallableDefaultModel]" has no attribute "objects"  [attr-defined]
tests/sentry/db/models/fields/test_jsonfield.py:165: error: "Type[CallableDefaultModel]" has no attribute "objects"  [attr-defined]
tests/sentry/db/models/fields/test_jsonfield.py:169: error: "Type[CallableDefaultModel]" has no attribute "objects"  [attr-defined]
tests/sentry/db/models/fields/test_jsonfield.py:170: error: "Type[CallableDefaultModel]" has no attribute "objects"  [attr-defined]
tests/sentry/db/models/fields/test_jsonfield.py:194: error: "Type[BlankJSONFieldTestModel]" has no attribute "objects"  [attr-defined]
Found 30 errors in 1 file (checked 1 source file)

will try and narrow it down to a minimal case but I've failed to do that so far

How is that should be

I expect no errors in that file

System information

• OS:
• python version: 3.8.16
• django version: 3.2.20
• mypy version: 1.5.1
• django-stubs version: 4.2.4
• django-stubs-ext version: 4.2.2

[asottile-sentry]

partially reverting #1672 fixes this so I suspect the removal of objects there isn't correct CC @flaeppe

--- a/mypy_django_plugin/transformers/models.py
+++ b/mypy_django_plugin/transformers/models.py
@@ -833,9 +833,9 @@ class MetaclassAdjustments(ModelClassInitializer):
         ):
             del ctx.cls.info.names["MultipleObjectsReturned"]

-        objects = ctx.cls.info.names.get("objects")
-        if objects is not None and isinstance(objects.node, Var) and not objects.plugin_generated:
-            del ctx.cls.info.names["objects"]
+        # objects = ctx.cls.info.names.get("objects")
+        # if objects is not None and isinstance(objects.node, Var) and not objects.plugin_generated:
+        #     del ctx.cls.info.names["objects"]

         return

[flaeppe]

I was looking at this a little earlier and I'm suspecting there's a configuration mismatch involved. I wasn't able to start up sentry though, but I admin I didn't try too hard either.

Anyways, I think all models within that file are test models but the django-stubs plugin relies heavily (unfortunately) on the runtime. So unless I'm reading stuff wrong, I'm suspecting that the runtime that django-stubs loads doesn't include the models specified in tests/sentry/db/models/fields/test_jsonfield.py? (Essentially since their app isn't in INSTALLED_APPS)

If they don't, the plugin will now delete objects but never add it back.. So perhaps the plugin should be more careful before deleting the objects attribute from what it sees as non-registered models..

I haven't verified this, but I think if one would set up an editable install of django-stubs and place a strategic print or so in here:

https://github.com/typeddjango/django-stubs/blob/939f91c4aba830bfa3341103dbf4b98bc86500b7/mypy_django_plugin/django/context.py#L102-L112

    @cached_property
    def model_modules(self) -> Dict[str, Dict[str, Type[Model]]]:
        """All modules that contain Django models."""
        modules: Dict[str, Dict[str, Type[Model]]] = defaultdict(dict)
        for concrete_model_cls in self.apps_registry.get_models():
            modules[concrete_model_cls.__module__][concrete_model_cls.__name__] = concrete_model_cls
            # collect abstract=True models
            for model_cls in concrete_model_cls.mro()[1:]:
                if issubclass(model_cls, Model) and hasattr(model_cls, "_meta") and model_cls._meta.abstract:
                    modules[model_cls.__module__][model_cls.__name__] = model_cls
+       print(modules)
        return modules

You could see which models django-stubs collects from the runtime.. I'm suspecting e.g. JSONFieldTestModel isn't included..

Another way might be to add in e.g. tests.sentry.db, if that's the app, to INSTALLED_APPS, run mypy again and see if any errors goes away.

[flaeppe]

Additionally I just want to point out that the real solution here is to have the plugin not add managers from the runtime model, but instead analyze the declared model(and its parents) and figure which manager attributes are implicitly added..

[asottile-sentry]

was removing objects solving something specific? it seems to be breaking a lot given the pinned issue and this and I'm not sure it's worth it at this point if we can't get it correct even with runtime analysis

[flaeppe]

was removing objects solving something specific? [...]

Not more than an attempt of better alignment with the runtime..

We probably need to relax that deletion until analysis of models is more sophisticated and independent of runtime models, if that'll ever happen

[ntessman-capsule]

You could see which models django-stubs collects from the runtime.. I'm suspecting e.g. JSONFieldTestModel isn't included..

Thanks for this @flaeppe, this solved my issue! The model in question hadn't been exported properly and wasn't visible to the app config. Very oblique error message and root cause, would not have guessed the issue.

[Tatsh]

Confused on this issue. I've pretty much switched to ._default_manager in my projects. You can add this to the exceptions in your linter like Ruff. It's odd but it's better than the workarounds IMO.