Propagating information. with cancellation

Community Support
1

Hi! I’m using Temporal with the Typescript SDK. In my use case I have an parent workflow who is listening for a signal that comes with an id of the user who cancelled the workflow.

That parent workflow also has a child workflow who creates some records in my DB. If there’s a cancellation, I’d like to be able to have it mark the records as cancelled and attach the id of who cancelled them.

From the docs I can’t figure out the best way to do this as I don’t see how you could attach any information when I call cancel on the cancellation scope in the parent workflow that the child workflow would be able to get access to. What’s the best way to do this?

1 Like
2

You could catch the cancelation and send a signal to the child (untested).

export async function parentWorkflow() {
  let cancelIdentity = "";
  workflow.setHandler(someSignal, ({ identity }) => {
    cancelIdentity = identity;
  });
  // Prevent workflow cancelation from propagating.
  await workflow.CancellationScope.nonCancellable(async () => {
    // Create another scope that we can control cancelling.
    await workflow.CancelationScope.cancellable(async () => { 
      const handle = workflow.startChild(....);
      return await Promise.race([
        (async () => {
          await workflow.condition(() => cancelIdentity !== "");
          await handle.signal(someOtherSignal, cancelIdentity);
          workflow.CancellationScope.current().cancel();
          return await handle.result();
        })(),
        handle.result(),
      ]);
    });

    
  })
}
3

I am also having this issue. I would love to have support for passing args to cancel(). It would make things a lot easier. The args would be available on the error object.