Bug[v5] An inline child actor cannot be persisted.

[zavx0z]

Description

<script>
	import { createMachine, assign, createActor } from "xstate"

const rootMachine = createMachine({
  context: {
    atoms: {},
  },
  on: {
    "actor.put": {
      actions: assign(({ context, event, spawn }) => {
        const { atoms } = context
        atoms["atom"] = spawn(event.params.atom, event.params.options)
        return { ...context, atoms: { ...atoms } }
      }),
    },
  },
  initial: "idle",
  states: {
    idle: {},
  },
})

const actor = createActor(rootMachine, { systemId: "root-actor" })
actor.subscribe((state) => {
  console.log(actor.getPersistedState())
})
actor.start()

const childMachine = createMachine({
  initial: "idle",
  states: {
    idle: {},
  },
})

actor.send({ type: "actor.put", params: { atom: childMachine, options: { systemId: "child-id", id: "child" } } })

</script>
<h1>xstate</h1>

Expected result

  VITE v4.5.0  ready in 3801 ms

  ➜  Local:   http://localhost:5173/
  ➜  Network: use --host to expose
  ➜  press h to show help
{
  value: 'idle',
  status: 'active',
  error: undefined,
  historyValue: {},
  matches: [Function: bound matches],
  toStrings: [Function: bound toStrings],
  output: undefined,
  context: { atoms: {} },
  children: {}
}
Error: An inline child actor cannot be persisted.
    at Object.getPersistedState (/home/projects/sveltejs-kit-template-default-je7z77/node_modules/xstate/dist/raise-b69a3d16.development.cjs.js:1441:13)
    at StateMachine.getPersistedState (/home/projects/sveltejs-kit-template-default-je7z77/node_modules/xstate/dist/xstate.development.cjs.js:586:37)
    at Actor.getPersistedState (/home/projects/sveltejs-kit-template-default-je7z77/node_modules/xstate/dist/interpreter-ed3f81f7.development.cjs.js:756:23)
    at eval (/home/projects/sveltejs-kit-template-default-je7z77/src/routes/+page.svelte:29:21)
    at Actor.update (/home/projects/sveltejs-kit-template-default-je7z77/node_modules/xstate/dist/interpreter-ed3f81f7.development.cjs.js:486:24)
    at Actor._process (/home/projects/sveltejs-kit-template-default-je7z77/node_modules/xstate/dist/interpreter-ed3f81f7.development.cjs.js:606:10)
    at Mailbox.flush (/home/projects/sveltejs-kit-template-default-je7z77/node_modules/xstate/dist/interpreter-ed3f81f7.development.cjs.js:54:12)
    at Mailbox.enqueue (/home/projects/sveltejs-kit-template-default-je7z77/node_modules/xstate/dist/interpreter-ed3f81f7.development.cjs.js:46:12)
    at Actor._send (/home/projects/sveltejs-kit-template-default-je7z77/node_modules/xstate/dist/interpreter-ed3f81f7.development.cjs.js:703:18)
    at Object._relay (/home/projects/sveltejs-kit-template-default-je7z77/node_modules/xstate/dist/interpreter-ed3f81f7.development.cjs.js:180:14)

Actual result

{"value":"idle","status":"active","historyValue":{},"context":{"atoms":{"atom":{"xstate$$type":1,"id":"child"}}},"children":{"child":{"state":{"value":"idle","status":"active","historyValue":{},"context":{},"children":{}},"systemId":"child-id"}}}

Reproduction

https://stackblitz.com/edit/sveltejs-kit-xstate?file=src%2Froutes%2F%2Bpage.svelte

Additional context

ts without sveltekit worked
https://stackblitz.com/edit/xstate-ts?file=index.ts

[davidkpiano]

This is working as expected; we currently cannot serialize arbitrary actor logic, nor do we plan to do this since it would require essentially serializing fully executable code. The machine needs to have the actor already defined (named src) to properly rehydrate it.

[Andarist]

We might be able to improve the situation for the new spawn action (as in entry: spawn(inlineLogic)) but that's it. This one we can always try to "recover" from the same config position (if it stays there)

[zavx0z]

Why does the same code work in vanilla, but give an error in Sveltekit?
sveltekit
vanila ts

[zavx0z]

This is working as expected; we currently cannot serialize arbitrary actor logic, nor do we plan to do this since it would require essentially serializing fully executable code. The machine needs to have the actor already defined (named src) to properly rehydrate it.

If I have a generated actor, then I cannot get PersistedState?
Could you take a closer look at the code examples and the output?
It seems to me that there is still a mistake here.
Everything is very unclear.

Sorry for Google translator.

[davidkpiano]

This is working as expected; we currently cannot serialize arbitrary actor logic, nor do we plan to do this since it would require essentially serializing fully executable code. The machine needs to have the actor already defined (named src) to properly rehydrate it.

If I have a generated actor, then I cannot get PersistedState? Could you take a closer look at the code examples and the output? It seems to me that there is still a mistake here. Everything is very unclear.

Sorry for Google translator.

No worries; in your code, you are passing an entire machine definition in the event. I would recommend another way of modeling it so that the machine knows about the other kinds of machines it can spawn already, instead of having that passed through an event.

[zavx0z]

No worries; in your code, you are passing an entire machine definition in the event. I would recommend another way of modeling it so that the machine knows about the other kinds of machines it can spawn already, instead of having that passed through an event.

Thanks for your reaction.
The modeling method you suggested does not suit me.
I am developing 3D, where an individual actor is created for each object. The parent state machine is mainly needed as a message passing system. How can I restore the states of dynamic objects? How to create a previously unknown number of actors?

[zavx0z]

is it possible to use actors without a parent actor in a single system?
How to share addresses between users if they are not on the same system?
If the actors can communicate directly, then I could write the logic of the system myself so that the actors can restore their state. It will also be possible to create a dynamic number of actors who can communicate with each other.
Please give me direction on where to go to fulfill my needs.

[burakakca]

Are there any changes in this regard?

[Andarist]

What kind of an inline child actor you'd like to persist? Could you show how your machine looks like?