I'm adding a new one2many field to notebook page sale_order called "On Site" that referencing old order of the same customer. I've got the sale_order_line and already compute the total qty. 

The problem is when the data is new, I can click the sale_order_line of old order inside page "On Site" then pop up of sale_order_line appear then I can edit the sale_order_line of old order inside page "On Site". 

This should not be possible because the data is compute. The product qty, price, etc is already computed and cannot be changed by user because this data is based on previous order of the same customer.

If the data is saved, the pop up field properly readonly

currently the on_site_ids is compute using @api.depends. I want the compute execute after the record is saved. Not before. So even the one2many data is appear, the popup field already readonly. How can I achieve this? ​