RuntimeError: Unable to resolve relationship user for wagtailcore.ModelLogEntry. Django is most likely not initialized, and its apps registry not populated. Ensure Django has finished setup before loading FilterSets

[Elrigor]

Hi!

I've updated to the LTS 4.1 but this error came out:

RuntimeError: Unable to resolve relationship `user` for `wagtailcore.ModelLogEntry`. Django is most likely not initialized, and its apps registry not populated. Ensure Django has finished setup before loading `FilterSet`s.

I have the following versions:

Wagtail 4.1
Django 4.0.8
django-filter 22.1]

My temporal "fix"

I was able to solve this by removing the user on the meta class of SnippetHistoryReportFilterSet :

    class Meta:
        model = ModelLogEntry
        fields = ["action", "**_user_**", "timestamp"]

This is located at wagtail/snippets/views/snippets.py

Is that a logger or something like that? If so, is there a way to disable it in order to use the page?

Thanks!

[gasman]

Thanks for the report @Elrigor! We've had a couple of reports of similar issues (e.g. #9582), although we haven't yet definitively determined what triggers it. It looks quite likely that it's related to custom user models, though - are you using one on your project?

As another workaround, calling register_snippet from a wagtail_hooks.py rather than as a decorator on the model seems to help - as per the last code snippet under https://docs.wagtail.org/en/stable/topics/snippets.html#customising-snippets-admin-views (but leaving out the viewset argument, as that's optional).

[Elrigor]

Hi, Thank you for your fast reply!
I was able to fix it by using the default User model and not the custom one I have. However, I need to use a custom user model :/

[dkirkham]

I'd have to roll back to an earlier commit in my project to confirm this, but I think I had a similar issue last week as I was coding the migration from 2.16 via 3.0 and 4.0 to 4.1rc1. It was resolved by putting the custom user module very early in the INSTALLED_APPS list (in settings), before any other module that referred to the user object.

[Elrigor]

That fixed it! Thank you mate 💯

[gasman]

Reopening this, as we do want to find a proper fix for this that allows previously-working code to continue working on 4.1.

[laymonage]

The filterset on the snippet history view has been there since 4.0, so I believe that's not the (only) cause.

In 4.1, we added this import, which causes the register_snippet function to load the wagtail.snippets.views.snippets module, which in turn imports the filterset before all models (including a custom User model) have been loaded in, raising this error.

[gasman]

Reproduced on a fresh Wagtail project as follows:

wagtail start customusersnippet
cd customusersnippet
./manage.py startapp customuser

Add "customuser" to INSTALLED_APPS after "home", and edit customuser/models.py as follows:

from django.db import models

from django.contrib.auth.models import AbstractUser

class CustomUser(AbstractUser):
    country = models.CharField(verbose_name='country', max_length=255)

Add AUTH_USER_MODEL = 'customuser.CustomUser' to settings.

Edit home/models.py as follows:

from django.db import models

from wagtail.models import Page
from wagtail.snippets.models import register_snippet


class HomePage(Page):
    pass


@register_snippet
class Advert(models.Model):
    text = models.TextField()

Now ./manage.py makemigrations (or any other management command, e.g. ./manage.py check) fails with:

Traceback (most recent call last):
  File "/Users/matthew/.virtualenvs/wagtail/lib/python3.8/site-packages/django_filters/utils.py", line 174, in get_field_parts
    opts = field.remote_field.model._meta
AttributeError: 'str' object has no attribute '_meta'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "./manage.py", line 10, in <module>
    execute_from_command_line(sys.argv)
  File "/Users/matthew/.virtualenvs/wagtail/lib/python3.8/site-packages/django/core/management/__init__.py", line 446, in execute_from_command_line
    utility.execute()
  File "/Users/matthew/.virtualenvs/wagtail/lib/python3.8/site-packages/django/core/management/__init__.py", line 420, in execute
    django.setup()
  File "/Users/matthew/.virtualenvs/wagtail/lib/python3.8/site-packages/django/__init__.py", line 24, in setup
    apps.populate(settings.INSTALLED_APPS)
  File "/Users/matthew/.virtualenvs/wagtail/lib/python3.8/site-packages/django/apps/registry.py", line 116, in populate
    app_config.import_models()
  File "/Users/matthew/.virtualenvs/wagtail/lib/python3.8/site-packages/django/apps/config.py", line 269, in import_models
    self.models_module = import_module(models_module_name)
  File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/importlib/__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1014, in _gcd_import
  File "<frozen importlib._bootstrap>", line 991, in _find_and_load
  File "<frozen importlib._bootstrap>", line 975, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 671, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 783, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "/Users/matthew/Development/tbx/wagtail/debug/customusersnippet/home/models.py", line 12, in <module>
    class Advert(models.Model):
  File "/Users/matthew/Development/tbx/wagtail/devscript/wagtail/wagtail/snippets/models.py", line 47, in register_snippet
    from wagtail.snippets.views.snippets import SnippetViewSet
  File "/Users/matthew/Development/tbx/wagtail/devscript/wagtail/wagtail/snippets/views/snippets.py", line 628, in <module>
    class SnippetHistoryReportFilterSet(WagtailFilterSet):
  File "/Users/matthew/.virtualenvs/wagtail/lib/python3.8/site-packages/django_filters/filterset.py", line 62, in __new__
    new_class.base_filters = new_class.get_filters()
  File "/Users/matthew/.virtualenvs/wagtail/lib/python3.8/site-packages/django_filters/filterset.py", line 325, in get_filters
    field = get_model_field(cls._meta.model, field_name)
  File "/Users/matthew/.virtualenvs/wagtail/lib/python3.8/site-packages/django_filters/utils.py", line 144, in get_model_field
    fields = get_field_parts(model, field_name)
  File "/Users/matthew/.virtualenvs/wagtail/lib/python3.8/site-packages/django_filters/utils.py", line 179, in get_field_parts
    raise RuntimeError(
RuntimeError: Unable to resolve relationship `user` for `wagtailcore.ModelLogEntry`. Django is most likely not initialized, and its apps registry not populated. Ensure Django has finished setup before loading `FilterSet`s.

Placing customuser first in INSTALLED_APPS avoids this.

[gasman]

Bisecting shows that 6e1e024 is the commit that triggered this issue.

[ababic]

Suggestion: Would it be viable to update register_snippet() to simply store the Snippet: Custom ViewSet mappings in another global, then do the actual 'viewset registering' later on?

[gasman]

@ababic That sounds like a good plan, yep! We're being a bit quirky with how we mix model and view code here, and while I think django-filter might be technically in the wrong for how early in the execution it's doing model lookups, making it less quirky wouldn't be a bad thing. :-)

[ababic]

@gasman I think you're right about django-filter. I think my suggestion needs something extra, otherwise users subclassing these viewsets and importing them into models.py to pass to register_snippet() are only going to bump into the same problem.

In addition to the above, maybe we make the 'viewset' argument accept a python path string? That way, we can keep that 'lazy' until we are ready to register views.

[gasman]

@gasman I think you're right about django-filter. I think my suggestion needs something extra, otherwise users subclassing these viewsets and importing them into models.py to pass to register_snippet() are only going to bump into the same problem.

If people are building custom viewsets to pass to register_snippet, they'll probably be doing that in wagtail_hooks (as that's the documented and less messy approach), which means the issue doesn't arise (since wagtail_hooks is only imported later, after models have been loaded) - so I think we're covered.