Update guide and support native Template Partials in Django 6.0

[wrabit]

Looking at migration guide https://github.com/carltongibson/django-template-partials/blob/main/Migration.md

Django Cotton guide at https://django-cotton.com/docs/django-template-partials would need the reference to "template_partials.apps.SimpleAppConfig" in INSTALLED_APPS to be removed.

Also the part regarding TEMPLATES customization probably need some experimentation regarding template_partials.loader which will be a Django built-in instead.

Maybe it would be best to have a separate docs page for "Django 6 built-in template partials" when this setup has been figured out as the Django 5.2 LTS version users will probably keep using the django-template-partials package for a while.

Originally posted by @jasalt in #302

[alorence]

Hi @wrabit.

I currently work on a project using django-template-partials and django-cotton. I plan to upgrade to django 6 soon, removing the dependency to partials and use the builtin feature instead.

If you need, I may help to test various use case and redact proper doc for this support.

Regards

[wrabit]

@alorence would be great - thank you

[georgeleege]

I was just about to make another issue but saw that maybe it would sense here.
In the current guide for integrating with template partials, there is a notice

Because we're specifying loaders manually, Django prevents us from using the APPS_DIRS setting. This means we need to specify the path to the templates directory(s) manually.

I'm not entirely sure what it is intended to mean, but I interpreted it as if I have my templates following the <app_name>/templates/<app_name> pattern, that I would have to put them all into DIRS.

I was annoyed at this idea, so I did some testing and read through #153

I used the following settings config:

INSTALLED_APPS = [
    # ...
    "django_cotton.apps.SimpleAppConfig",
    "template_partials.apps.SimpleAppConfig",
    # ...
]

TEMPLATES = [
    {
        "BACKEND": "django.template.backends.django.DjangoTemplates",
        "DIRS": [],
        "OPTIONS": {
            "loaders": [
                (
                    "template_partials.loader.Loader",
                    [
                        (
                            "django.template.loaders.cached.Loader",
                            [
                                "django_cotton.cotton_loader.Loader",
                                "django.template.loaders.filesystem.Loader",
                                "django.template.loaders.app_directories.Loader",
                            ],
                        )
                    ],
                )
            ],
            "context_processors": [
                # ...
            ],
            "builtins": [
                "django_cotton.templatetags.cotton",
                "template_partials.templatetags.partials",
            ],
        },
    },
]

All of my existing templates in <app_name>/templates/<app_name> still worked.
Then I created <app_a>/templates/cotton/a.html and <app_b>/templates/cotton/b.html and was able to use both the <c-a> and <c-b> cotton components in another template.

So I'm really not sure if I'm missing the point of the notice or if it can be removed.

Also I think django-cotton is a great project and would be happy to help with testing also.