Recursive app dependencies django - django

Question

Django's INSTALLED_APPS is a list in the settings file, which ultimately the devops girl/guy of the wsgi-application is responsible for.
However, when creating an app, I often use templates and templatetags of other apps, for example django-bootstrap4. Consider a simple bootstrap4-with-butter app, that only proivides this template:
bs4wb/templates/bs4wb/base.html
{% extends "bootstrap4/bootstrap4.html" %}
{% block bootstrap4_extra_head %}
<script> confirm('with butter?!'); </script>
{% endblock bootstrap4_extra_head %}
It is not enough for the devops to install and add to INSTALLED_APPS
bs4wb, they also need to do the same for django-bootstrap4, and moreover, he/she also needs to keep track of the version I used whenever I upgrade from django-bootstrap4 to django-bootstrap5` or something. That is, I need to document an extra step which can change.
How can I specify recursive INSTALLED_APPS? Is there something like an app-union? For example (obviously ugly syntax, sorry):
export('bs4wb', app_by_union(['bootstrap4', 'bs4wb']) )
which would insert bootstrap4 and bs4wb next to each other whenever bs4wb is added to INSTALLED_APPS?
Or should I just raise an exception if bootstrap4 was not added to installed apps, stating that it should be added.

Answer 1

As an app developer you usually use django's system check framework to ensure the environment fits your requirements.
In your case you'll check whether another app is included in INSTALLED_APPS and add an error, if not.
It might look like that (untested):
from django.conf import settings
from django.core.checks import Error, register
#register()
def bootstrap4_check(app_configs, **kwargs):
errors = []
if not 'django-bootstrap4' in settings.INSTALLED_APPS:
errors.append(
Error('django-bootstrap4 needs to be in INSTALLED_APPS')
)
return errors
If your requirements change with new versions: adjust the checks.