How to emit events from actor logic such as fromObservable

[reramjiawan]

Hi,

I have a question regarding emitting from actorLogic which is invoked such as fromObservable or fromPromise. When I emit using the provided emit method from the actorLogic I don't understand why this event is not bubbling up to the parent when listening for events.

Example:

const subject = new Subject();

const observableLogic = fromObservable<unknown, any, AnyEventObject>(({ emit }) => {
  return subject.pipe(
    tap((v) => {
      emit({ type: 'EMITTED', value: v });
    })
  );
});

const parentMachine = createMachine({
  initial: 'idle',
  states: {
    idle: {
      invoke: {
        src: observableLogic,
        onDone: {
          target: 'done',
        },
      },
      on: {
        EMITTED: {
          actions: emit({
            type: 'test',
          }),
        },
      },
    },
    done: {},
  },
});

const service = createActor(parentMachine);

service.on('*', (emitted) => {
  console.log('emitted?');
});

service.on('EMITTED', (emitted) => {
  console.log('emitted?');
});

service.start();

// Emit a value from the Subject
subject.next('Hello, world!');
subject.complete();

Please let me know if I am doing something wrong here or my expectations are not right.

[reramjiawan]

After playing around with XState I have found better suitable patterns. Thanks!

[GabrielAPineiro]

If you don't mind me asking, what was your solution for this case? I'm having the same issue, and I'm not understanding why the event is not being called. I have another machine with a similar case and the event is being fired with no problems

[reramjiawan]

Hi @GabrielAPineiro,

See this part in the docs https://stately.ai/docs/invoke#invoking-event-observables. Just return events from your observables and the rest is handled by the machine. From there you can do whatever you need, sendTo or whatever else.

[GabrielAPineiro]

That's crazy. I have a machine which worked with fromObservable, same logic of actor returning event and it being called automatically. But my second machine only worked with the fromEventObservable.
Thank you for the help!

[matheo]

@reramjiawan I see Event observables working, but I don't see event.output with fromObservable.

I'm doing an API call with Angular rxjs but the result is not propagated to onDone nor onSnapshot.
The documentation mentions that the data is saved to the fromObservable actor context, but how to access it?
or why onSnapshot event is not delivering the data?