Find out if a field has changed when an element is changed?

Question

1C-Bitrix

In the element update event handler (OnAfterIBlockElementUpdate), how do you know if a field has changed and which fields have changed at all?
or how to get the fields BEFORE the change so that you can compare

Answer 1

You need to use OnBeforeIBlockElementUpdate for this

Answer 2

Set up Bitrix logs, write the necessary variables in the AddMessage2Log code and look in the logs for what data these variables got
https://dev.1c-bitrix.ru/api_help/main/functions/d...