site
- id
- location
- address

circuit
- id
- name
- ref

sitecircuits
- site_id
- circuit_id
- active_link

class MonitoringConnectivitySet(viewsets.ModelViewSet):
    queryset = SiteCircuits.objects.all()
    serializer_class = MonitoringSerializerConnectivity
    permission_classes = (IsAdminUser,)
    filter_class = SiteCircuits
    filter_backends = (filters.SearchFilter,)
    search_fields = ('site__id','circuit__id')

class MonitoringSerializerConnectivity(serializers.ModelSerializer):

    class Meta:
        model = SiteCircuits
        fields = ('site_id','circuit_id','active_link',)

router.register(r'conn_set', views.MonitoringConnectivitySet)

path('conn_set/<int:site_id>/<int:circuit_id>/', views.MonitoringConnectivitySet)

class Meta:
    model = SiteCircuits
    fields = ('site_id','circuit_id','active_link',)

def get_queryset(self):
        site_id = self.kwargs['site_id']
        circuit_id = self.kwargs['circuit_id']
        return SiteCircuits.objects.filter(site_id=site_id,circuit_id=circuit_id)

class MonitoringConnectivitySet(viewsets.ModelViewSet):
    queryset = SiteCircuits.objects.all()
    serializer_class = MonitoringSerializerConnectivity
    permission_classes = (IsAdminUser,)