How to filter by fields of nested objects?

[devinnasar]

Hello,

I have a serializer with multiple fields which are themselves serializers:

class HostSerializer(serializers.HyperlinkedModelSerializer):
    id = serializers.IntegerField(required=False)

    class Meta:
        model = Host
        fields = ('id', 'private_ip', 'public_ip', 'fqdn', 'type', 'load_balancer_fqdn')

class TenantSerializer(WritableNestedModelSerializer):

    tenant_name = serializers.CharField(source='name', read_only=False)
    tenant_environment = EnvironmentSerializer(source='environment', many=False, read_only=False, partial=True)
    app_host = HostSerializer(many=False, read_only=False, partial=True)
    db_host = HostSerializer(many=False, read_only=False, partial=True)
    version = VersionSerializer(many=False, read_only=False, partial=True)
    settings = SettingSerializer(many=True, read_only=False, partial=True)

    class Meta:
        model = Tenant
        fields = ('id', 'tenant_name', 'tenant_environment', 'active', 'description', 'adi_number', 'version', 'app_host', 'db_host', 'settings')

It seems to work well enough to specify 'app_host' as a filterset field in my TenantViewSet, and I can get Tenants with an App Host of a target pk value:

class TenantViewSet(viewsets.ModelViewSet):
    """
    API Endpoint that allows Tenants to be viewed or edited.
    """
    # querysets are collections of objects returned from the Django API
    queryset = Tenant.objects.all().order_by('name')
    serializer_class = TenantSerializer
    permission_classes = [permissions.IsAuthenticated]
    filter_backends = (filters.DjangoFilterBackend,)
    filterset_fields = ('name', 'app_host', 'db_host', 'version')

However, how does one go about filtering Parent objects by their relationship to Child objects with a specific field value, for instance, if I wanted to say "Give me all Tenants who are on an App Host with load_balancer_fqdn = 'X'"?

[palomapiot]

I think this is what you are looking for: db_host__load_balancer_fqdn (https://docs.djangoproject.com/en/dev/topics/db/queries/#lookups-that-span-relationships)