drf_file_upload.py

class FileUploadSerializer(serializers.Serializer):
    attachment = serializers.FileField()
    
    
class FileUploadView(views.APIView):
    '''
    FileUploadParser - is some sort of retardnes, 
    it takes entier http body and parses it as a file 0_0.
    Very useful! Specially trash headers, prepended to the text file...
    So, just don't use it ;-> Use MultiPartParser instead.
    '''
    parser_classes = [MultiPartParser]
    # in this case, we need that only for standard DRF HTML pages, 
    # which uses a client, when visits an endpoint.
    serializer_class = FileUploadSerializer

    def put(self, request, **kwargs):
        serializer = self.serializer_class(data=request.data)
        serializer.is_valid(raise_exception=True)
        file_obj = request.FILES['attachment']
        reader = csv.reader(file_obj.file)
        # ...
        # do fun with file
        # ...
        return Response({}, status=status.HTTP_201_CREATED)