How to save value on Readonly / editable false fields in odoo Models?

Question

I've a field which I want to compute it's value on change, but I don't want the user can modify it.

If I set the field as readonly=1 or editable=0 the value isn't store.

I'm trying to set a global discount on the invoice

class account_invoice(models.Model):
    _inherit = "account.invoice"

    global_discount_p = fields.Float('Descuento porcentaje')
    global_discount = fields.Float('Descuento')
    neto = fields.Float('Neto')

    @api.one
    @api.depends('invoice_line.price_subtotal', 'tax_line.amount','global_discount_p')
    def _compute_amount(self):
        ret = super(account_invoice,self)._compute_amount()
        if self.type == 'in_invoice':
            self.neto = self.amount_untaxed
            discount = self.global_discount_p/100
            self.global_discount = self.neto * discount
            self.amount_untaxed = self.neto - self.global_discount

            for line in self.tax_line:
                line.base = self.amount_untaxed
                line.amount = line.amount - (line.amount * discount)

            self.amount_tax = sum(line.amount for line in self.tax_line)
            self.amount_total = self.amount_untaxed + self.amount_tax

        return ret

And in the layout:

<xpath expr="//field[@name='amount_untaxed']" position="before">
                <field name="neto" readonly="1"/>
                <field name="global_discount_p" onchange="_compute_amount"/>
                <field name="global_discount" readonly="1"/>
            </xpath>

It work well, if I remove readonly="1" attrs from the fields

Answer 1

In odoo11 you can use force_save="1" in the xml file

Hope it will help you!!