Django Rest Framework: Get singular object using the root API

Question

I am trying to set up an API endpoint that returns a singular object.

Right now I have:

class ShoppingCartViewSet(viewsets.GenericViewSet, mixins.ListModelMixin):
    """
    API endpoint that allows users to be viewed or edited.
    """
    serializer_class = ShoppingCartSerializer
    authentication_classes = (TokenAuthentication,)
    permission_classes = (IsAuthenticated,)

    def get_paginated_response(self, data):
        return Response(data)

    def get_queryset(self):
        return ShoppingCart.objects.filter(user=self.request.user)

Which uses the ListModelMixin and a filter to return one item, becasue each user has 1 shopping cart.

The issue is the filter function returns a queryset, but I only want a single item.

I attempted to use the RetrieveModelMixin but that doesn't run on the endpoint that I want. Retrieve runs on .../api/shopping-cart/id but I want to retrieve on .../api/shopping-cart because the filtering is done via the person who is logged in.

Any solutions?

Answer 1

The way I ended up solving it was still using the ListModelMixin, as I needed to benefits of the viewset.

I overwrote the list() method with:

class ShoppingCartViewSet(viewsets.GenericViewSet, mixins.ListModelMixin):
    """
    API endpoint that allows users to be viewed or edited.
    """
    serializer_class = ShoppingCartSerializer
    # authentication_classes = (TokenAuthentication,)
    # permission_classes = (IsAuthenticated,)

    def get_paginated_response(self, data):
        return Response(data)

    def list(self, request, *args, **kwargs):
        instance = ShoppingCart.objects.get(user=self.request.user)
        serializer = self.get_serializer(instance)
        return Response(serializer.data)

which returns me a singular item on the root url .../api/shopping-cart without having to pass parameters because it filters based on user.