from odoo import models, api class EventRegistration(models.Model): _inherit = "event.registration" def action_set_done(self): super().action_set_done() for regis in self: tic_prod = regis.event_ticket_id.product_id bal_prod = tic_prod.balance_variant_id if tic_prod.is_event_deposit and bal_prod: order = regis.sale_order_id lines = order.order_line line = lines.filtered(lambda sol: sol.product_id == bal_prod, limit=1) if line: # Update existing line update_values = order._prepare_order_line_update_values( line, line.product_uom_qty + 1 ) if update_values: order._update_cart_line_values(line, update_values) else: # Create new line line_values = order._prepare_order_line_values(bal_prod, 1) line.sudo().create(line_values)