Deep nested objects in django won't work due to async

先从 issue 中的 Subscription、TaskType 和 TaskResultType resolver 示例开始，然后使用 Django 设置复现嵌套的 task → result → profiles subscription。跟踪 async-context 错误发生的位置，并验证完整的嵌套 subscription 能够返回 profile 数据，而无需额外的 resolver 变通方案。

• GraphQL AioWS version: (not using AioWS, only django-channels)
• Python version: 3.8.2
• Operating System: MacOSX

Description

I am trying to get clients to subscribe to my graphql with a nested object in django. The request looks like this:

subscription {
  taskUpdated(id:"04a5e92bc9084ad981481ab4314a1d33", updateInterval: 3) {
    id
    token
    result {
      id,
      profiles {
        id
      }
    }
  } 
}

Tasks contain one result which contain multiple profiles.

What I Did

In my subscription class I used the sync_to_async method which works if used for the first level:

class Subscription(graphene.ObjectType):
    task_updated = graphene.Field(
        TaskType, id=graphene.String(), update_interval=graphene.Int()
    )

    async def resolve_task_updated(root, info, id, update_interval):
        print("TRYING TO RESOLVE")
        while True:
            print("While true")
            task = await sync_to_async(Task.objects.get, thread_sensitive=True)(
                pk=id
            )
            yield task
            await asyncio.sleep(update_interval)

Using the query only targeting task.id everything works perfectly. Once I try to target task.result (which is a new object). I receive the error:

You cannot call this from an async context - use a thread or sync_to_async.

I managed to get a workaround by updating the TaskType and updating the resolver for the result like so:

class TaskType(DjangoObjectType):
    class Meta:
        model = TaskModel
        fields = "__all__"

    result = graphene.Field(TaskResultType)

    async def resolve_result(self, info):
        return await sync_to_async(
            TaskResult.objects.get, thread_sensitive=True
        )(task=self.id)

That way I could get to the next level (task -> result). When I try to subscribe to task -> result -> profiles there is no way to receive the data anymore. The same error from above is thrown. Even if I update the ResultType accordingly to fetch all profiles async:

class TaskResultType(DjangoObjectType):
    class Meta:
        model = TaskResult
        fields = "__all__"

    profiles = graphene.List(ProfileType)

    async def resolve_profiles(self, info):
        return await sync_to_async(
            Profile.objects.filter, thread_sensitive=True
        )(task_result=self.id)

I thought dynamic querying of objects and subscribing to nested objects would be an out of the box functionality but it is really difficult. I can't be the only person using this repo to actually receive ORM data?