Python/Django warnings

I recently updated a Django project from 1.8 to 1.11. In the process, I started turning warnings into errors. Django docs recommend resolving any deprecation warnings with current version, before upgrading to a new version of Django. In this case, I didn’t start my upgrade work by resolving warnings, but I did run the tests with warnings enabled for part of the process.

Here’s how to enable all warnings when you’re running your tests:

1. From the CLI
   • use -Werror to raise Exceptions for all warnings
   • use -Wall to print all warnings
2. In the code
   • import warnings; warnings.filterwarnings(‘error’) – raise Exceptions on all warnings
   • import warnings; warnings.filterwarnings(‘always’) – print all warnings

If a project runs with no warnings on a Django LTS release, it’ll (generally) run on the next LTS release as well. This is because Django intentionally tries to keep compatibility shims until after a LTS release, so that third-party applications can more easily support multiple LTS releases.

Enabling warnings is nice because you see warnings from python or other packages, so you can address whatever problems they’re warning about, or at least know that they will be an issue in the future.