Mutating the output of step.do

[Mael-Abgrall]

Existing documentation URL(s)

• https://developers.cloudflare.com/workflows/build/rules-of-workflows/#do-not-rely-on-state-outside-of-a-step

What changes are you suggesting?

On the workflow documentation, there is a mention that we should not rely on the state outside of a step; however, there is no mention about mutating the state.

Would the state be reset to the first instance, or kept in memory?

Additional information

let myOutput = await step.do('something', async () => {
  return Number(1);
});
while (myOutput < 10) {
  await step.sleep("💤💤💤💤", "3 hours");
  myOutput = await step.do('something', async () => {
    return myOutput + 1;
  });
}

In this example, would myOutput be 1 or 10?

[Caio-Nogueira]

The state returned by a step is persisted and you can rely on it. In fact that's what you should do if you need its computation to complete exactly once. All remaining state that gets declared within your run method will possibly be computed more than once. This is a consequence of how we call into your WorkflowEntrypoint from the Workflows control plane. This doesn't necessarily mean that you must not use state outside of a step. You just need to be careful about idempotency and determinism (i.e.: all state outside of a step must be replayable).

To answer your question, since your example purely relies on state returned from steps, you should see iterations of the something step with monotonically increasing outputs until the last step returns 10.

[Mael-Abgrall]

great thanks

[kodster28]

Looks like this question has been answered, so closing out the issue