Is it possible to send data from a child machine to parent?

[panesofglass]

I am attempting to share data between child machines through the parent's context. However, I'm having a hard time determining how to pass data from a child machine back to the parent machine without using a final state, which I don't want to use. Is there a data option that can be used with sendParent, or do I need to use an EventObject to pass data?

Original:
I'm currently invoking child machines from a parent machine to orchestrate several, related workflows. I would like these to remain available, as it is possible to jump back and forth, and I want to retain the last state of each. However, I also need to share state from the children with one another. I know I can use a final state and pass data through onDone, but I'd like to not do that. I could potentially spawn the machine each time and initialize it with the parent context. Is there another way?

[Andarist]

I'm not sure if I have understood correctly because the content of the issue doesn't match the title as far as I can tell.

But if you just want to send something from a child to a parent then sendParent should be what you are looking for. If you want to send an event to a sibling then you can also do this, but you have to share target's sessionId first - which can be done through events. That sessionId is always set as _event.origin.

[panesofglass]

Thank you, @Andarist. I updated my question. The first option of using sendParent is what I've tried, but for some reason, I get a errors when trying to send an event object. Perhaps I just need to add additional typings to the event object I try to send to make TypeScript happy.

The second option is interesting, but I don't think I've seen either sessionId or _event.origin in any docs or logged objects. Do you have an example to which you could link?

[Andarist]

Thank you, @Andarist. I updated my question. The first option of using sendParent is what I've tried, but for some reason, I get a errors when trying to send an event object. Perhaps I just need to add additional typings to the event object I try to send to make TypeScript happy.

Yeah, u might need to provide an extra type param or smth. If you prepare a runnable repro case then I could help you with that.

The second option is interesting, but I don't think I've seen either sessionId or _event.origin in any docs or logged objects. Do you have an example to which you could link?

You can get it from the third argument given to your actions/conds/others: https://github.com/davidkpiano/xstate/blob/73f5802d86d5689d367281c37c4f0aaee7003450/packages/core/test/event.test.ts#L26-L27