AWS Amplify AppSync Subscription not working correctly

Question

I wrote a small application that subscribes to DB changes using AWS Amplify CLI / AppSync. All amplify api calls work perfectly (mutations, queries) but unfortunately the observer does not receive events. I can see that the MQTT socket receives periodically binaries but I can't obtain changed objects.

I configured Amplify for amplify use. I can see in the debugger that the AppSyncProvider has been initisalised. Also tried API and PubSub but makes no difference.

        const awsmobile = {
            "aws_appsync_graphqlEndpoint": "https://[...].appsync-api.[...]/graphql",
            "aws_appsync_region": "[...]",
            "aws_appsync_authenticationType": "AMAZON_COGNITO_USER_POOLS",
        };

        Amplify.configure(awsmobile);

        ngOnInit() 
            {
                try {

                  this.apiService.OnUpdateA.subscribe(
                    {
                        next: (x) => {[...]},
                        error: (e) => {[...]},
                        complete: () => {[...]}
                    });
                } 
                catch (error) {[...]    }
            }

        ***Schema***
        type A
        @model 
        @auth(rules: [
              {allow: owner},
              {allow: groups, groups: ["A"], operations: [create, update, read]},
              {allow: groups, groups: ["B"], operations: [read]},
          ]) 
        {
          id: ID!
          entry: AnotherType! @connection(name: "AnotherConnection")
    [...]
        }

 OnUpdateAListener: Observable<
    OnUpdateASubscription
  > = API.graphql(
    graphqlOperation(
      `subscription OnUpdateA($owner: String) {
        onUpdateA(owner: $owner) {
          __typename
          id
          owner
       [...]
        }
      }`
    )
  ) as Observable<OnUpdateASubscription>;

Anyone for any ideas?

**Logs:**
{mqttConnections: Array(1), newSubscriptions: {…}, provider: Symbol(INTERNAL_AWS_APPSYNC_PUBSUB_PROVIDER)}
mqttConnections: Array(1)
0: {url: "wss://[...]-ats.iot.[...].amazonaws…[...]%3D%3D", topics: Array(2), client: "[...]"}
length: 1
__proto__: Array(0)
newSubscriptions:
onUpdate:
expireTime: 1573313050000
topic: "[....]/22tmaezjv5555h4o7yreu24f7u/onUpdate/1cd033bad555ba55555a20690d3e04e901145776d3b8d8ac95a0aea447b273c3"
__proto__: Object
__proto__: Object
provider: Symbol(INTERNAL_AWS_APPSYNC_PUBSUB_PROVIDER)
__proto__: Object

However, not sure whether it is suspicious that the subscription Object has no queue?

Subscription {_observer: {…}, _queue: undefined, _state: "ready", _cleanup: ƒ}
_cleanup: ƒ ()
_observer:
next: (x) => {…}
__proto__: Object
_queue: ***undefined***
_state: "ready"
closed: (...)
__proto__: Object

Many thanks in advance.

Answer 1

I had the same problem with GraphQL. Thing is: we have to return Owner in mutation response in order to let Subscription know to whom to send this event.

removing {allow: owner} did worked for me but thats not the right way since we require it in order to have owner based access to data.

so the correct way i found is:

if subscription is:

    subscription MySubscription {
  onCreateuser(owner: "$userName") {
    id
    name
    number
  }
}

mutation should be:

mutation MyMutation {
  createUser(input: {name: "xyz", id: "user123", number: "1234567890"}) {
    id
    name
    number
    owner
  }
}

we must return owner in mutation's response in order to get the subscription to that event and all other properties as same as mutation response.