Django Middleware for django-template-partials

middleware.py

class HtmxPartialTemplateMiddleware:
    """Adds support for rendering partials with django-template-partials.
    
    NOTES
    -----
    In order for this middleware to work properly, the following conditions must be met:
    
    1) django-template-partials must be installed
    2) Each template must have a partial defined directly in it with a name that coincides
       with the HTML id of the element being swapped out. Since django-template-partials does
       not support rendering partials defined in parent templates, you must be careful when
       using Django's {% extends %} syntax.
    3) One nice benefit of this method, is if you create partials surrounding your <forms> and
       then set the `HX-Retarget` to e.g., `#form` in a view's `form_invalid()` method, then the
       middleware will render the form errors and `HX-Retarget` will replace the submitted form
       with validated form, showing the errors.

    """

    DEFAULT_PARTIAL_NAME = 'main'

    def __init__(self, get_response) -> None:
      self.get_response = get_response

    def __call__(self, request: HttpRequest) -> HttpResponse:
      response = self.get_response(request)
      if request.htmx and (response.status_code == 302):
        response = HttpResponseClientRedirect(response.url)
      return response

    def process_template_response(self, request, response):
      if request.htmx:
        if retarget_id := response.get('HX-Retarget'):
          partial_name = retarget_id.strip('#')
        else:
          partial_name = request.htmx.target or self.DEFAULT_PARTIAL_NAME

        response.template_name = [
          f'{template_name}#{partial_name}'
          if '#' not in template_name
          else template_name
          for template_name in response.template_name
        ]
      return response

Some notes about django-template-partials and this middleware:

1. This works great if you want to use Django's built in generic class-based views (or subclasses thereof)
2. If not being able to render partials defined in parent templates is a deal breaker for you, consider using django-render-block, although a middleware like this would not work as well since django-render-block does not tie into the template rendering system (so a middleware with process_template_response would not work, since the view would not being returning a TemplateResponse object). It's probably best to use django-render-block if you're using function based views.

I'm by no means an expert at this stuff, simply documenting what I've learned trying to combine HTMX and class-based views. If you have any thoughts, suggestions, questions, or enhancements, I'd love to hear them.