leaders_function.py

    # Add this to the UserViewSet

    @action(detail=False, methods=("GET", "POST",))
    def leaders(self, request):
        if request.method == "GET":
            leaders_ids = CustomUser.objects.filter(
                leader_id__isnull=False
            ).distinct().values_list("leader_id", flat=True)
            leaders_queryset = CustomUser.objects.filter(id__in=leaders_ids)
            return_serializer = UserListSerializer(leaders_queryset, many=True)
            return Response(return_serializer.data, status.HTTP_200_OK)

        elif request.method == "POST":
            ids_serializer = SetLeaderSerializer(data=request.data)
            if ids_serializer.is_valid(raise_exception=True):
                user = ids_serializer.validated_data.get("user")
                leader = ids_serializer.validated_data.get("leader")
                
                user.leader = leader
                user.save()
                
                return Response(ids_serializer.data, status.HTTP_200_OK)