Config MyPy for Django and pure python project in monorepo structure

[mrvafa]

I'm facing a configuration problem with Pants + mypy in a monorepo.

pure_python/
django_project/
utils/
pyproject.toml
pants.toml

I’m trying to keep a monorepo layout. The problem arises when executing:

pants check ::

I have set mypy to use django-stubs for type checking inside of django_project, but the Django-specific mypy configuration is being applied to all Python targets including pure_python. This causes errors such as:

django_project.settings not found

because pure_python obviously has no Django settings module. I want Django type-checking with django-stubs only for django_project/. However MyPy seems to apply plugin config globally. This makes non-Django packages fail pants check.

Is there a recommended way to scope mypy configuration to only certain targets / source roots so that Django settings aren't required for unrelated packages?

Thanks!

[benjyw]

Can you mock up a repo that demonstrates this? There are potentially many moving parts, and it's hard to know what exactly is going on without seeing them all in action

[mrvafa]

Here is the example project.

example-django-python.zip

in server directory, running pants package ./python: has no issue. but running it in python directory will fail.

ModuleNotFoundError: No module named 'server'

[benjyw]

Hi, I haven't forgotten about this, but I'm on vacation until Jan 6th, will look at this after that.

Meanwhile could you put that example project in a github repo? That way we can iterate on it if necessary.

[mrvafa]

Here’s the GitHub repository:
https://github.com/mrvafa/example-of-python-django-using-pants

Thanks for following up!

[benjyw]

How do you reproduce the mypy issue you're having? pants check :: works for me.

[mrvafa]

I'm running pants check :: in python and server directories.

[benjyw]

OK, this is not surprising. python does not depend on server and so does not pull it in to the sandbox. But your pyproject.toml contains django_settings_module = "server.core.settings" which causes Django to look for that package.

In other words you've configured your repo under the assumption that server is always available.

Note that you can run pants check :: in the root directory, and that works because server is part of that ::.

[benjyw]

Going to close this as answered, but feel free to reopen if necessary!