what should i do for minus(-) x_discount_rate from amount_total

class PurchaseOrder(models.Model): 
_name = "purchase.order"
_inherit = ['mail.thread', 'ir.needaction_mixin']
_description = "Purchase Order"
_order = 'date_order desc, id desc'


@api.depends('order_line.price_total')
def _amount_all(self):
for order in self:
amount_untaxed = amount_tax = 0.0
for line in order.order_line:
amount_untaxed += line.price_subtotal
# FORWARDPORT UP TO 10.0
if order.company_id.tax_calculation_rounding_method == 'round_globally':
taxes = line.taxes_id.compute_all(line.price_unit, line.order_id.currency_id, line.product_qty, product=line.product_id, partner=line.order_id.partner_id)
amount_tax += sum(t.get('amount', 0.0) for t in taxes.get('taxes', []))
else:
amount_tax += line.price_tax
order.update({
'amount_untaxed': order.currency_id.round(amount_untaxed),
'amount_tax': order.currency_id.round(amount_tax),
'amount_total': amount_untaxed + amount_tax
})

Hi,

You have to call the field like self.field_name or as per the context. If you simply give x_discount_rate it will be considered as a variable and system will look for defined variable. So just update the code with self.x_discount_rate and see.

Not sure it has to be given self. you can check the rest of the function and see how the other fields are called and do accordingly

Thanks