Autofill custom event attribute

you can try something like #_ATT{Field}{Default Value}

https://wp-events-plugin.com/documentation/event-attributes/

That won’t work because the default value is another custom attribute which a user will enter manually. Can’t do: #_ATT{Parent_Code}{#_ATT{Child_Code}}

It seems like i would need run a query that triggers on saving the event that would get a sub-string of #_ATT{Child_Code}, assign it to #_ATT{Parent_Code) then save it to the db.

Maybe you could direct on how to hook to the Save Event action? Or, an example.

Thank you Angelo.

The saving process and functions used can be found in this file:

/events-manager/classes/em-event-post-admin.php

Thanks for pointing the file.