How in django python, using the middleware, to change the content of the page before it is displayed by render in the view?

Question

Django

https://docs.djangoproject.com/en/2.1/topics/http/...
The reference information indicates which part of the code is executed before and which after view .
But nothing is said about how to change the generated content of the page before it is displayed after view .

class SimpleMiddleware:
    def __init__(self, get_response):
        self.get_response = get_response
        # One-time configuration and initialization.

    def __call__(self, request):
        # Code to be executed for each request before
        # the view (and later middleware) are called.

        response = self.get_response(request)

        # Code to be executed for each request/response after
        # the view is called.

        return response

The question is how to update the content of request or response so that after self.get_response(request) the updated process_template_response data is displayed on the page?

Code snippet:

my_middleware.py

class MyMiddleware(object):

    def __init__(self, get_response=None):
        if get_response is not None:
            self.get_response = get_response

    def __call__(self, request):
        request.test_context = '1. __call__'
        # print(request.test_context)
        self.process_request(request)
        response = self.get_response(request)
        response = self.process_template_response(request, response)
        return response

    def process_request(self, request):
        request.test_context += ' - 2. process_request'
        # print(request.test_context)

    def process_template_response(self, request, response):
        request.test_context += ' - 4. process_template_response'
        # print(request.test_context)
        return response

views.py

def test_context(request):
    request.test_context += ' - 3. view'
    # print(request.test_context)
    return render(request, 'my_app/test_context.html')

test_context.html
{{request.test_context}}

Using print I track the change in the request.test_context variable :
1. __call__
1. __call__ - 2. process_request
1. __call__ - 2. process_request - 3. view
1. __call__ - 2. process_request - 3. view - 4. process_template_response

But the html page displays:
1. __call__ - 2. process_request - 3. view

What needs to be fixed to see

1. __call__ - 2. process_request - 3. view - 4. process_template_response

instead

of 1. __call__ - 2. process_request - 3. view

?

Versions:
Django==2.1
Python==3.7

Answer 1

So far, I have solved it by a workaround:

from django.shortcuts import render

    def render_test_context(request, template_name):
        request.test_context += ' - 4. process_template_response'
        # print(request.test_context)
        return render(request, template_name)

from my_app.my_render import render_test_context

def test_context(request):
    request.test_context += ' - 3. view'
    # print(request.test_context)
    return render_test_context(request, 'my_app/test_context.html')

Answer 2

If you are not satisfied with the result of generating a page from a template in a view, remake the template. Redo the view. For this, templates and views are invented.
The view renders a template based on the data. The rendered template (after the view) no longer has any {{request.test_context}} and other machinery. There is only ready to issue html. Therefore, no "- 4. process_template_response" will appear there.
Either use the tools for their intended purpose or do the post-process with your hands (change the generated html with greps and regexps). But this is a really strange decision. What could be missing BEFORE the view call, but appeared AFTER and you can't use it in the template now because it's too late?