How inject a field into a blocking flow action?

[David_O]

I have a flow with a Filter (blocking) Event hook that triggers on item.Create. I want to add a field to the payload. I can seem to inject or append the new data without overwriting the existing payload. So my records are being created but missing the data from the original payload.
What am I doing wrong? And yes, it has to be a blocking action so the new field is created before the record is written.

Any help very much appreciated!

[Burvs]

I normally do that with a script rather than using transform payload. Just add an additional parameter to the payload like this:

new_payload = data.$trigger.payload
new_payload[“new_parameter”] = “foo”
return (new_payload)

Then make sure in the Trigger Setup, you have response body set to “data of last operation”.