Django model “doesn't declare an explicit app_label”

Question

I\'m at wit\'s end. After a dozen hours of troubleshooting, probably more, I thought I was finally in business, but then I got:

Model class django.contrib.co         


        

Answer 1

In my case, this was happening because I used a relative module path in project-level urls.py, INSTALLED_APPS and apps.py instead of being rooted in the project root. i.e. absolute module paths throughout, rather than relative modules paths + hacks.

No matter how much I messed with the paths in INSTALLED_APPS and apps.py in my app, I couldn't get both runserver and pytest to work til all three of those were rooted in the project root.

Folder structure:

|-- manage.py
|-- config
    |-- settings.py
    |-- urls.py
|-- biz_portal
    |-- apps
        |-- portal
            |-- models.py
            |-- urls.py
            |-- views.py
            |-- apps.py

With the following, I could run manage.py runserver and gunicorn with wsgi and use portal app views without trouble, but pytest would error with ModuleNotFoundError: No module named 'apps' despite DJANGO_SETTINGS_MODULE being configured correctly.

config/settings.py:

INSTALLED_APPS = [
    ...
    "apps.portal.apps.PortalConfig",
]

biz_portal/apps/portal/apps.py:

class PortalConfig(AppConfig):
    name = 'apps.portal'

config/urls.py:

urlpatterns = [
    path('', include('apps.portal.urls')),
    ...
]

Changing the app reference in config/settings.py to biz_portal.apps.portal.apps.PortalConfig and PortalConfig.name to biz_portal.apps.portal allowed pytest to run (I don't have tests for portal views yet) but runserver would error with

RuntimeError: Model class apps.portal.models.Business doesn't declare an explicit app_label and isn't in an application in INSTALLED_APPS

Finally I grepped for apps.portal to see what's still using a relative path, and found that config/urls.py should also use biz_portal.apps.portal.urls.