QueryOptimizer does not work when returning Node interface

[blb-ventures]

QueryOptimizer does not work when returning Node interface

[bellini666]

Hey @yergom !

I think that the issue is because you defined it using gql.field instead of gql.django.field. Could you try that?

Also, it should work with just node: gql.Node = gql.django.node() (please tell me if it doesn't)

But if you have non django types implementing the Node interface, then the resolver would need to workaround that. It should not be complicated 3 to 5 lines of code should do that and I can tell you want exactly needs to be done, but lets see if you really need that first =P

[yergom]

I've tried both options, and none of them optimize the query. The reproduction steps are fairly simple. Given the following model:

class Container(models.Model):
    name = models.TextField()

class Item(models.Model):
    name = models.TextField()
    container = models.ForeignKey(Container, related_name="items", on_delete=models.CASCADE)

@gql.django.type(Item)
class ItemType(gql.Node):
    name: gql.auto
    container: "ContainerType"

@gql.django.type(Container)
class ContainerType(gql.Node):
    name: gql.auto
    items: List[ItemType]

@gql.type
class Query:
    node: gql.Node = gql.django.node()
    
    @gql.django.connection
    def all_containers(self) -> Iterable[ContainerType]:
        return Container.objects.all()

And instantiating 1 container with 10 items, the following query:

query all {
  allContainers{
    edges{
      node{
        id
        name
	items{
          name
        }
      }
    }
  }
}

requires 3 sql queries (1 for counting, 1 for getting the container id/name, and 1 for the prefetch of Items), whereas the following query:

query node{
  node(id:"UD"){
    ... on Container{
      name
      items{
        name
      }
    }
  }
}

is creating 13 sql queries. So no prefetch and no only optimization.

[bellini666]

Hey @yergom ,

Just to ask you if you had any luck working around your issue? I unfortunately didn't have much time those days to check this. Will try to do soon though.

[yergom]

Hey @bellini666, unfortunately I haven't had time either. For now, my (poor's man) solution is to create independent query fields per type, which is obviously not ideal.

[bellini666]

@yergom this should be fixed in the release 1.11 that I'm doing atm. Please reopen if it is not.