Request does not raise UnsupportedMediaType exception

[Feverfew]

Checklist

• I have reduced the issue to the simplest possible case.

With the following view:

@api_view(['POST'])
@parser_classes([JSONParser])
def my_view(request):
    request.data['change_me'] = 'MyValue'

By sending a request with Content-Type: multipart/form-data (with at least one key/value pair, if it's empty it still goes through but doesn't trip up weirdly enough) one will observe the following behaviour:
AttributeError at $myViewsURL This QueryDict instance is immutable

What surprises me is that as I've specified the use of only the JSONParser, I should expect request.data to be a dict. I've tried other content-types and they are correctly rejected before parsing, but this one goes through.

[lovelydinosaur]

Guiding you kindly towards discussions... :)

I'm not able to replicate this...

urls.py

from django.urls import path
from rest_framework.decorators import api_view, parser_classes
from rest_framework.parsers import JSONParser


@api_view(['POST'])
@parser_classes([JSONParser])
def homepage(request):
    request.data['change_me'] = 'MyValue'


urlpatterns = [
    path('', homepage),
]

client.py:

import httpx

r = httpx.post("http://127.0.0.1:8000", data={"a":"b"})
print(r)

shell:

$ python client.py 
<Response [415 Unsupported Media Type]>