Hello, 

i had to override the create function in sale order line model to create a bonus sale order line depending on a certain condition.

the problem is when i duplicate a sale order it creates two bonus sale order lines not only one.

is there a way to avoid that? or should i find another way to create the bonus line 

here's my code:

class PricelistItem(models.Model):
    _inherit = "product.pricelist.item"

    compute_price = fields.Selection([
        ('fixed', 'Fixed Price'),
        ('percentage', 'Percentage (discount)'),
        ('formula', 'Formula'),
        ('bonus', 'Bonus')], index=True, default='fixed', required=True)

    ordered_quantity = fields.Float('Ordered Quantity', digits='Product Unit of Measure', default=0)
    bonus_quantity = fields.Float('Bonus Quantity', digits='Product Unit of Measure', default=0)


class CustomSaleOrderLine(models.Model):
    _inherit = "sale.order.line"

    active = fields.Boolean(default=True, readonly=True)
    ordered_quantity = fields.Float('Ordered Quantity', digits='Product Unit of Measure', readonly=True, default=0)
    bonus_quantity = fields.Float('Bonus Quantity', digits='Product Unit of Measure', readonly=True, default=0)

    @api.model
    def create(self, vals):
        lines = super(CustomSaleOrderLine, self).create(vals)
        PricelistItem = self.env['product.pricelist.item']
        for line in lines:
            product_context = dict(line.env.context, partner_id=line.order_id.partner_id.id, date=line.order_id.date_order,
                                   uom=line.product_uom.id)
            final_price, rule_id = line.order_id.pricelist_id.with_context(product_context).get_product_price_rule(line.product_id, line.product_uom_qty or 1.0, line.order_id.partner_id)
            if rule_id:
                pricelist_item = PricelistItem.browse(rule_id)
                if pricelist_item.compute_price == 'bonus':
                    if line.product_uom_qty >= pricelist_item.ordered_quantity:
                        line.bonus_quantity = pricelist_item.bonus_quantity
                        sol = self.env['sale.order.line'].create({
                            'name': line.product_id.name,
                            'product_id': line.product_id.id,
                            'product_uom_qty': pricelist_item.bonus_quantity,
                            'product_uom': line.product_id.uom_id.id,
                            'price_unit': 0,
                            'active': False,
                            'order_id': line.order_id.id,
                        })
        return lines

thanks