Global Transition to a "catch-all-do-cleanup-exit-nicely" state

Question

I have a catch all error state that does some cleanup for my application and exits nicely.

currently I have to create a specific event {type: "unexpected_error"} and add a transition to every single state of my machine to achieve that.

Is there a simpler way that I can specify a transition for all states so I don't have to add this transition to every single state?

score 4 · Accepted Answer · answered Jul 15 '19 at 03:30

Yes! You can place transitions on the top-level machine.

const machine = Machine({
  // ...
  states: { /*...*/ },
  // top-level transition
  on: {
    "unexpected-error": { actions: /*...*/ }
  }
});

Alternatively, since it's just a JavaScript object, so you can make a helper function:

function transitionsWithErrorHandler(transitions) {
  return {
    ...transitions,
    "unexpected-error": { actions: /*...*/ }
  }
}

// ...
states: {
  foo: {
    on: transitionsWithErrorHandler({
      EVENT: 'bar',
      ANOTHER_EVENT: 'baz'
    })
  }
}

Global Transition to a "catch-all-do-cleanup-exit-nicely" state

1 Answers1