Return Django ORM union result in Django-Graphene - postgresql

Question

I am trying to query two separate objects and return them as a single result set. I've tried using a Union and an Interface, but not sure what I'm doing wrong there.
My model:
class BaseActivity(models.Model):
class Meta:
abstract = True
name = models.CharField(db_column="activity_type_name", unique=True, max_length=250)
created_at = CreationDateTimeField()
modified_at = ModificationDateTimeField()
created_by = models.UUIDField()
modified_by = models.UUIDField()
deleted_at = models.DateTimeField(blank=True, null=True)
deleted_by = models.UUIDField(blank=True, null=True)
class Activity(BaseActivity):
class Meta:
db_table = "activity_type"
ordering = ("sort_order",)
id = models.UUIDField(
db_column="activity_type_id",
primary_key=True,
default=uuid.uuid4,
editable=False,
)
sort_order = models.IntegerField()
def __str__(self):
return self.name
class CustomActivity(BaseActivity):
class Meta:
db_table = "organization_custom_activity_type"
id = models.UUIDField(
db_column="organization_custom_activity_type",
primary_key=True,
default=uuid.uuid4,
editable=False,
)
farm = models.ForeignKey("farm.Farm", db_column="organization_id", on_delete=models.DO_NOTHING, related_name="custom_activity_farm")
My schema:
class FarmActivities(graphene.ObjectType):
id = graphene.String()
name = graphene.String()
class ActivityType(DjangoObjectType):
class Meta:
model = Activity
fields = ("id", "name", "requires_crop", "sort_order")
class CustomActivityType(DjangoObjectType):
class Meta:
model = CustomActivity
fields = ("id", "name", "farm")
And the query:
class Query(graphene.ObjectType):
get_farm_activities = graphene.Field(FarmActivities, farm=graphene.String(required=True))
def resolve_get_farm_activities(self, info, farm):
farm_activities = Activity.objects.values("id", "name").filter(
farmtypeactivityrel__farm_type__farm=farm, deleted_at=None
)
custom_activities = CustomActivity.objects.values("id", "name").filter(farm=farm, deleted_at=None)
return list(chain(farm_activities, custom_activities))
With this, I do get a list back from the query, but it's not going thru the resolver when I call getFarmActivities.
Literally the list returns:
ExecutionResult(data={'getFarmActivities': {'id': None, 'name': None}}, errors=None)

Answer 1

How to resolve graphene.Union Type?
That provided the hint I needed to get this working. I had to build a Union that would parse the model and not the schema type.
class FarmActivities(graphene.Union):
class Meta:
types = (ActivityType, CustomActivityType)
#classmethod
def resolve_type(cls, instance, info):
if isinstance(instance, Activity):
return ActivityType
if isinstance(instance, CustomActivity):
return CustomActivityType
return FarmActivities.resolve_type(instance, info)
Which then allowed me to run the query like so:
def resolve_get_farm_activities(self, info, farm):
farm_activities = Activity.objects.filter(
farmtypeactivityrel__farm_type__farm=farm
)
custom_activities = CustomActivity.objects.filter(farm=farm)
return list(chain(farm_activities, custom_activities))
And the API query:
query farmParam($farm: String!)
{
getFarmActivities(farm: $farm)
{
... on CustomActivityType
{
id
name
}
... on ActivityType
{
id
name
}
}
}