Intermittent "circular import" when starting Django app

Hi,

Thanks for a nice Python/Django package. It works fine, but sometimes I get this error on startup with this Django app installed (as described in the installation details):

pipenv run ./manage.py runserver
Watching for file changes with StatReloader
2021-04-20 13:37:09,008 INFO [django.utils.autoreload] Watching for file changes with StatReloader
Performing system checks...

Traceback (most recent call last):
  File "/home/per/.virtualenvs/centraln-czG2gyNf/lib/python3.9/site-packages/django/template/utils.py", line 66, in __getitem__
    return self._engines[alias]
KeyError: 'django'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/per/.virtualenvs/centraln-czG2gyNf/lib/python3.9/site-packages/django/template/backends/django.py", line 121, in get_package_libraries
    module = import_module(entry[1])
  File "/usr/lib/python3.9/importlib/__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1030, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1007, in _find_and_load
  File "<frozen importlib._bootstrap>", line 986, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 680, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 790, in exec_module
  File "<frozen importlib._bootstrap>", line 228, in _call_with_frames_removed
  File "/home/per/.virtualenvs/centraln-czG2gyNf/lib/python3.9/site-packages/django_simple_bulma/templatetags/django_simple_bulma.py", line 11, in <module>
    from ..utils import (
ImportError: cannot import name 'fontawesome_token' from partially initialized module 'django_simple_bulma.utils' (most likely due to a circular import) (/home/per/.virtualenvs/centraln-czG2gyNf/lib/python3.9/site-packages/django_simple_bulma/utils.py)

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/home/per/git/centraln/./manage.py", line 22, in <module>
    main()
  File "/home/per/git/centraln/./manage.py", line 18, in main
    execute_from_command_line(sys.argv)
  File "/home/per/.virtualenvs/centraln-czG2gyNf/lib/python3.9/site-packages/django/core/management/__init__.py", line 419, in execute_from_command_line
    utility.execute()
  File "/home/per/.virtualenvs/centraln-czG2gyNf/lib/python3.9/site-packages/django/core/management/__init__.py", line 413, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/home/per/.virtualenvs/centraln-czG2gyNf/lib/python3.9/site-packages/django/core/management/base.py", line 354, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/home/per/.virtualenvs/centraln-czG2gyNf/lib/python3.9/site-packages/django/core/management/commands/runserver.py", line 61, in execute
    super().execute(*args, **options)
  File "/home/per/.virtualenvs/centraln-czG2gyNf/lib/python3.9/site-packages/django/core/management/base.py", line 398, in execute
    output = self.handle(*args, **options)
  File "/home/per/.virtualenvs/centraln-czG2gyNf/lib/python3.9/site-packages/django/core/management/commands/runserver.py", line 96, in handle
    self.run(**options)
  File "/home/per/.virtualenvs/centraln-czG2gyNf/lib/python3.9/site-packages/django/core/management/commands/runserver.py", line 103, in run
    autoreload.run_with_reloader(self.inner_run, **options)
  File "/home/per/.virtualenvs/centraln-czG2gyNf/lib/python3.9/site-packages/django/utils/autoreload.py", line 637, in run_with_reloader
    start_django(reloader, main_func, *args, **kwargs)
  File "/home/per/.virtualenvs/centraln-czG2gyNf/lib/python3.9/site-packages/django/utils/autoreload.py", line 622, in start_django
    reloader.run(django_main_thread)
  File "/home/per/.virtualenvs/centraln-czG2gyNf/lib/python3.9/site-packages/django/utils/autoreload.py", line 327, in run
    autoreload_started.send(sender=self)
  File "/home/per/.virtualenvs/centraln-czG2gyNf/lib/python3.9/site-packages/django/dispatch/dispatcher.py", line 180, in send
    return [
  File "/home/per/.virtualenvs/centraln-czG2gyNf/lib/python3.9/site-packages/django/dispatch/dispatcher.py", line 181, in <listcomp>
    (receiver, receiver(signal=self, sender=sender, **named))
  File "/home/per/.virtualenvs/centraln-czG2gyNf/lib/python3.9/site-packages/django/template/autoreload.py", line 41, in watch_for_template_changes
    for directory in get_template_directories():
  File "/home/per/.virtualenvs/centraln-czG2gyNf/lib/python3.9/site-packages/django/template/autoreload.py", line 14, in get_template_directories
    for backend in engines.all():
  File "/home/per/.virtualenvs/centraln-czG2gyNf/lib/python3.9/site-packages/django/template/utils.py", line 90, in all
    return [self[alias] for alias in self]
  File "/home/per/.virtualenvs/centraln-czG2gyNf/lib/python3.9/site-packages/django/template/utils.py", line 90, in <listcomp>
    return [self[alias] for alias in self]
  File "/home/per/.virtualenvs/centraln-czG2gyNf/lib/python3.9/site-packages/django/template/utils.py", line 81, in __getitem__
    engine = engine_cls(params)
  File "/home/per/.virtualenvs/centraln-czG2gyNf/lib/python3.9/site-packages/django/template/backends/django.py", line 25, in __init__
    options['libraries'] = self.get_templatetag_libraries(libraries)
  File "/home/per/.virtualenvs/centraln-czG2gyNf/lib/python3.9/site-packages/django/template/backends/django.py", line 43, in get_templatetag_libraries
    libraries = get_installed_libraries()
  File "/home/per/.virtualenvs/centraln-czG2gyNf/lib/python3.9/site-packages/django/template/backends/django.py", line 108, in get_installed_libraries
    for name in get_package_libraries(pkg):
  File "/home/per/.virtualenvs/centraln-czG2gyNf/lib/python3.9/site-packages/django/template/backends/django.py", line 123, in get_package_libraries
    raise InvalidTemplateLibrary(
django.template.library.InvalidTemplateLibrary: Invalid template library specified. ImportError raised when trying to load 'django_simple_bulma.templatetags.django_simple_bulma': cannot import name 'fontawesome_token' from partially initialized module 'django_simple_bulma.utils' (most likely due to a circular import) (/home/per/.virtualenvs/centraln-czG2gyNf/lib/python3.9/site-packages/django_simple_bulma/utils.py)
make: *** [Makefile:24: serve] Error 1

Note that this only happens sometimes, which is both puzzling and annoying. It can also happen when making a change to any .py file in the project, i.e. when the apps are reloaded. Any ideas? Thanks in advance.

[lemonsaurus]

Haha, no problem. I appreciate your willingness to let us know!

[perlun]

Heh. Please disregard that one. It was a genuine circular dependency in my own app… 🙈 🙈 🙈 😁 I found and fixed it now.