Unable to access url parameter and response is NAN

[John Owolabi Idogun]

I am building a kind of an analytic dashboard and needed to make some valuable data available via WebSocket for a real-time experience. The API was initially built using DRF's ModelViewset with the response data preprocessed using pandas. I basically have the following view:

class FrequencyViewSet(viewsets.ModelViewSet):
    serializer_class = FrequencySerilizer

    def list(self, request, *args, **kwargs):
        print(request.GET.get('meter_id'))
        frequency_data = Meter.history.filter(
            meter_id=request.GET.get('meter_id')).values_list('frequency', flat=True)
        df = read_frame(frequency_data, fieldnames=[
                        'frequency']).mean()
        res = [
            {
                'frequency': df[0]
            }
        ]
        return Response(res)

Using view_as_consumer, I tried to make it available via WebSocket like so:

websocket_urlpatterns = [
    re_path(r'^ws/meter/frequency/',
            view_as_consumer(consumers.FrequencyViewSet.as_view({'get': 'list'}))),
]

I connected to the WebSocket via wscat:

wscat -c "ws://localhost:8000/ws/meter/frequency/?meter_id=OND101"

And tried accessing the list action with the following:

{"action":"list", "request_id": 42}

I however got the following response:

{"errors": [], "data": [{"frequency": NaN}], "action": "list", "response_status": 200, "request_id": 42}

And on the log, the print statement I had there printed None to the console.

If I access the same endpoint via HTTP, without wrapping the viewset with view_as_consumer, I get the following response:

[
  {
    "frequency": 50.1
  }
]

Is there anything I am missing here?

• OS: [e.g. Pop!_OS]
• Version [e.g. 20.10]
• Django (v. 4.0)

[Matthaus Woolard]

Good point, view_as_consumer currently does not pass through query params.

im not sure if it should since you might want to make multiple calls with the same WS connection open.

what I will add is the ability to include a query field in the ws message that will map to GET params.

[John Owolabi Idogun]

How can this parameter be accessed in the view's method?

[Matthaus Woolard]

These values are written to the GET just like a query string so you should be able to use the same view code as you do for regular requests.

eg GET.get('meter_id') will read 42 from {"action":"list", "request_id": 42, 'query': {'meter_id': 42}}

I have one other change I want to finish off then I will do a new release but if you want to try this before the release you can get pip to install from master branch