When editing the Django project's settings.py, when calling pylint we get a Django error message saying the config was not properly set, even though we correctly pass the flag --django-settings-module.

The problem is particular to modifications to settings.py, since modifications to any other file are still correctly processed by pylint.

Steps to reproduce:

1. Install pylint and pylint-django
2. Open a Django app (I cannot supply code for mine since it's closed source)
3. Edit the settings app; in our tests, we did

INSTALLED_APPS = [
...
"django_extensions",
]

(installing django-extensions is not required though) 4. Run pylint with pylint-django

pylint --load-plugins=pylint_django --django-settings-module=myapp.settings

Traceback

Traceback (most recent call last):
  File "/mnt/ubuntu_home/tomaz/git/Estágio/Scala/scala_alocacao/venv/lib/python3.10/site-packages/pylint_django/checkers/foreign_key_strings.py", line 92, in open
    django.setup()
  File "/mnt/ubuntu_home/tomaz/git/Estágio/Scala/scala_alocacao/venv/lib/python3.10/site-packages/django/__init__.py", line 19, in setup
    configure_logging(settings.LOGGING_CONFIG, settings.LOGGING)
  File "/mnt/ubuntu_home/tomaz/git/Estágio/Scala/scala_alocacao/venv/lib/python3.10/site-packages/django/conf/__init__.py", line 82, in __getattr__
    self._setup(name)
  File "/mnt/ubuntu_home/tomaz/git/Estágio/Scala/scala_alocacao/venv/lib/python3.10/site-packages/django/conf/__init__.py", line 63, in _setup
    raise ImproperlyConfigured(
django.core.exceptions.ImproperlyConfigured: Requested setting LOGGING_CONFIG, but settings are not configured. You must either define the environment variable DJANGO_SETTINGS_MODULE or call settings.configure() before accessing settings.

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/mnt/ubuntu_home/tomaz/git/Estágio/Scala/scala_alocacao/venv/lib/python3.10/site-packages/pylint_django/checkers/foreign_key_strings.py", line 120, in open
    settings.configure(Settings(self.config.django_settings_module))
  File "/mnt/ubuntu_home/tomaz/git/Estágio/Scala/scala_alocacao/venv/lib/python3.10/site-packages/django/conf/__init__.py", line 170, in __init__
    mod = importlib.import_module(self.SETTINGS_MODULE)
  File "/usr/lib/python3.10/importlib/__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1050, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1027, in _find_and_load
  File "<frozen importlib._bootstrap>", line 992, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 241, in _call_with_frames_removed
  File "<frozen importlib._bootstrap>", line 1050, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1027, in _find_and_load
  File "<frozen importlib._bootstrap>", line 1004, in _find_and_load_unlocked
ModuleNotFoundError: No module named 'scala_alocacao'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/mnt/ubuntu_home/tomaz/git/Estágio/Scala/scala_alocacao/venv/bin/pylint", line 8, in <module>
    sys.exit(run_pylint())
  File "/mnt/ubuntu_home/tomaz/git/Estágio/Scala/scala_alocacao/venv/lib/python3.10/site-packages/pylint/__init__.py", line 22, in run_pylint
    PylintRun(argv or sys.argv[1:])
  File "/mnt/ubuntu_home/tomaz/git/Estágio/Scala/scala_alocacao/venv/lib/python3.10/site-packages/pylint/lint/run.py", line 358, in __init__
    linter.check(args)
  File "/mnt/ubuntu_home/tomaz/git/Estágio/Scala/scala_alocacao/venv/lib/python3.10/site-packages/pylint/lint/pylinter.py", line 1073, in check
    self._check_files(
  File "/mnt/ubuntu_home/tomaz/git/Estágio/Scala/scala_alocacao/venv/lib/python3.10/site-packages/pylint/lint/pylinter.py", line 1108, in _check_files
    with self._astroid_module_checker() as check_astroid_module:
  File "/usr/lib/python3.10/contextlib.py", line 135, in __enter__
    return next(self.gen)
  File "/mnt/ubuntu_home/tomaz/git/Estágio/Scala/scala_alocacao/venv/lib/python3.10/site-packages/pylint/lint/pylinter.py", line 1236, in _astroid_module_checker
    checker.open()
  File "/mnt/ubuntu_home/tomaz/git/Estágio/Scala/scala_alocacao/venv/lib/python3.10/site-packages/pylint_django/checkers/foreign_key_strings.py", line 125, in open
    self.add_message(
  File "/mnt/ubuntu_home/tomaz/git/Estágio/Scala/scala_alocacao/venv/lib/python3.10/site-packages/pylint/checkers/base_checker.py", line 112, in add_message
    self.linter.add_message(
  File "/mnt/ubuntu_home/tomaz/git/Estágio/Scala/scala_alocacao/venv/lib/python3.10/site-packages/pylint/lint/pylinter.py", line 1631, in add_message
    self._add_one_message(
  File "/mnt/ubuntu_home/tomaz/git/Estágio/Scala/scala_alocacao/venv/lib/python3.10/site-packages/pylint/lint/pylinter.py", line 1564, in _add_one_message
    self.stats.increase_single_module_message_count(
  File "/mnt/ubuntu_home/tomaz/git/Estágio/Scala/scala_alocacao/venv/lib/python3.10/site-packages/pylint/utils/linterstats.py", line 300, in increase_single_module_message_count
    self.by_module[modname][type_name] += increase
KeyError: '/mnt/ubuntu_home/tomaz/git/Estágio/Scala/scala_alocacao/pylintrc'

System configuration

pip freeze

asgiref==3.5.1
astroid==2.11.4
black==22.3.0
cfgv==3.3.1
click==8.1.3
dill==0.3.4
distlib==0.3.4
Django==3.2.13
django-phonenumber-field==5.2.0
django-smart-selects==1.5.9
filelock==3.6.0
identify==2.5.0
isort==5.10.1
lazy-object-proxy==1.7.1
mccabe==0.7.0
mypy-extensions==0.4.3
mysqlclient==2.0.3
nodeenv==1.6.0
numpy==1.21.6
pathspec==0.9.0
phonenumbers==8.12.26
Pillow==9.1.0
platformdirs==2.5.2
pre-commit==2.16.0
pylint==2.13.0
pylint-django==2.5.3
pylint-plugin-utils==0.7
python-dateutil==2.8.2
pytz==2022.1
PyYAML==6.0
reportlab==3.6.2
six==1.16.0
sqlparse==0.4.2
toml==0.10.2
tomli==2.0.1
virtualenv==20.14.1
wrapt==1.14.1

pylintrc

[MASTER]

fail-on=E
fail-under=7.0
load-plugins=pylint_django
py-version=3.8

[MESSAGES CONTROL]

disable=missing-module-docstring,
        missing-class-docstring,
        missing-function-docstring

[REPORTS]

output-format=colorized
reports=no
score=yes

[BASIC]

good-names=i,
           j,
           k,
           ex,
           obj,
           Run,
           _

[DJANGO FOREIGN KEYS REFERENCED BY STRINGS]

django-settings-module=scala_alocacao.settings

We stumbled upon this bug when running pylint through pre-commit; in that case, we worked around this issue by running git commit --no-verify when changing settings.py, in case anyone else goes through something similar.