General statechart chat (https://statecharts.dev / https://github.com/statecharts/statecharts/discussions) — for XState Q&A → https://github.com/davidkpiano/xstate/discussions
We recently started using xstate for our statemanagement in react. So, we have a Xstate machine which contains all the context and necessary rules for transitions. And we have a nested functional, which is a typical parent component containing many child components. So is there anyway to access parent machine state (or the context to be precise) from child component without passing them as props to child component?
spawn()a machine with a state which has been "rehydrated" like this orderMachine.resolveState(previousState)? My use case is to store the state of an OrderMachine and then load it into a PurchaseMachine at a later date. Does that make sense?
const exampleMachine = {
states: {
type: "parallel",
states: {
load: {
doWork: {},
success: { type: "final" },
failed: { type: "final" },
},
},
onDone: {
// navigate to next state according to final state
},
},
};
spawn-ing child machine. I set it's instance on context as per docs. Child machine does some (async-ish) job and sendParent() the result. All works great.Could you please advise if I can suspend (to localStorage or DB) the state of a child machine from parent one using e.g.
invoke?And then restore child machine (if necessary) on future runs?
Thank you.
PS: Just saw a reply to similar question a few messages earlier. No worries.
In v4, you can use
pure() to ensure correct action orderAnd v5 already supports the correct order of actions with
assign; you can NPM install the next branch from GitHub locally: https://remarkablemark.org/blog/2016/09/19/npm-install-from-github/
Next after actions are not been assigned to actions
5 replies
Hi,
Playing with XState actions+guards.....
From my experiments today, an action wont get executed if its guard evaluates to false
The docs don't refer to such use-case
Anyone experienced the same? or different?
"processResults": {
"on": {
"Result": [
{
"internal": true,
"actions": "updateCounter",
"cond": {
"type": "someGuard"
}
}
]
}
}"processResults": {
"on": {
"Result": {
"internal": true,
"actions": [
"updateCounter",
{
"type": "xstate.send",
"event": {
"type": "checkCounter"
}
}
]
},
"checkCounter": [
{
"target": "success",
"cond": {
"type": "someGuard <=== This transition will get selected if this condition passes (after the updateCounter took place)
}
},
{
"internal": true <=== This transition will get selected if the above someGuard will return false.
}
]
}
},
1 reply
i love your xstate library.
one question: i couldn't figure out from the documentation is when i invoke a spawning of a new machine and give it a custom name, how exactly do i stop the machine?
- maybe i missed it, but none of the objects seemed to have a
.stop()method.
another question: i have my state machines running, but sometimes the process crashes or i do not expect a specific network event any time soon (which would trigger the next transition)- so i'd like to either temporary shut down or in case of crash, restart a machine, but it needs to be in a specific state with a specific context.
- i can call
.withContext(...), but probably again a bignner problem - couldn't figure out how to make it start out in one or multiple states (in case its a parallel machine or something)
2 replies
Felt challenged by a tweet from @davidkpiano. https://twitter.com/DavidKPiano/status/1374752085938466816
A circuit breaker machine https://stackblitz.com/edit/circuit-breaker — any feedback will be appreciated.
In case someone is interested, I decoupled first version of Visualiser into npm-package
Is there a standard pattern for actors who have a dependency on data managed by another actor?
Let's say I have a CheckoutMachine and a CartMachine, and the CheckoutMachine needs to create or update a payment intent any time the items change in the cart.
Which of these is more idiomatic?
- Use the data from the broadcasted
CartMachineevent to fetch/update the payment intent - Store the data from the event on context, and then use context data to perform the fetch
1 reply
Hi all, I was impressed once again with the simplicity and yet powerful concepts of statecharts. I was able to really improve my code with the concepts together with the reducer hook.
I was wondering if anyone knows articles/papers comparing statecharts to category theory it seems to me that statescharts and the actor model can be expressed as categories (or not, idk). But if you know any articles related to that please do share. Thanks.
I have an example and can show the issue - here it is
2 replies