Groovy - Copy Product custom field value to Opportunity revenue field

Summary:

How to copy a Product custom field's value to an Opportunity Revenue line item field?

Content (required):

Hi,

I have a custom field ABC on Product table. When the user adds a revenue line on an opportunity and then selects a Product, I want the value in ABC field for the selected product to be copied in a, say, XYZ field on Opportunity Revenue table.

I have made the field XYZ visible on the Opportunity products table. I tried writing a groovy script on Opportunity Revenue Create trigger but it executes before I select a product. I also tried adding a field trigger on InventoryItemID field but this doesn't seem to trigger when I select a product.