Clarify documentation about default implementation of `http_method_not_allowed`

[xingyu lin]

​https://docs.djangoproject.com/en/5.2/ref/class-based-views/base/#django.views.generic.base.View.http_method_not_allowed

The quoted description:

If the view was called with an HTTP method it doesn’t support, this method is called instead.

The default implementation returns HttpResponseNotAllowed with a list of allowed methods in plain text.

The original description would make you assume that it returns HttpResponseNotAllowed(http 405) with content containing a list of allowed methods in plain text.

But in fact, the default implementation returns HttpResponseNotAllowed with headers[Allow] containing a list of allowed methods in plain text, not in the content.

class TestView(View):
  def get(self, req):
    return HttpResponse('ok')

class Test(TestCase):
  def test(self):
    resp = self.client.post('/test')

    # The content is empty.
    # Allowed methods are in headers['Allow'].
    self.assertEqual(resp.content, b'')
    self.assertEqual(resp.headers['Allow'], 'GET, HEAD, OPTIONS')

[zubair]

Please assign this ticket to me, i am working on this.

[zubair]

This is the pull request i have created for this ticket.

​https://github.com/django/django/pull/20181

[xingyu lin]

Got it, thanks for your work.

[Youngkwang Yang]

I think it would be good to add an RFC reference.

like:

        The default implementation returns ``HttpResponseNotAllowed`` with the list of allowed methods 
        in the ``Allow`` header. The response body is empty, as required by :rfc:`RFC 7231 <7231#section-6.5.5>`. 

[zubair]

RFC reference added.

[zubair]

Replying to xingyu lin:

Got it, thanks for your work.

You are most welcome.
And thank you for your kind and quick response.

[zubair]

Please merge this PR.

[Youngkwang Yang]

Replying to zubair:

Please merge this PR.

Just a note: this ticket is still in "Unreviewed" stage. A Django core developer
will need to triage and accept it before merging. Let's wait for their review.

See the contribution process here: ​https://docs.djangoproject.com/en/dev/internals/contributing/triaging-tickets/#triage-stages

[Jacob Walls <jacobtylerwalls@…>]

In ff843bc:

Fixed #36734 -- Clarified the behavior of View.http_method_not_allowed.