I'm trying to implement a feature that allows the user to duplicate a sales order line. This wouldn't be very hard to implement if the rows were already stored in the database and had IDs, but in this case the user should be able to duplicate a sales order line BEFORE saving the sales order.

Correct me if I'm wrong, but AFAIK the sales order lines are only stored in the database after the sales order has been saved.

Am I going to need some javascript magic here or is the some kind of a mechanism in Odoo that allows me to duplicate unsaved items?