Odoo -添加或编辑one2many字段时的计算

from odoo import models, fields, api

class SaleOrder(models.Model):
    _name = 'sale.order'
    _description = 'Sale Order'

    name = fields.Char(string='Order Reference', required=True)
    order_line = fields.One2many('sale.order.line', 'order_id', string='Order Lines')

class SaleOrderLine(models.Model):
    _name = 'sale.order.line'
    _description = 'Sale Order Line'

    order_id = fields.Many2one('sale.order', string='Order Reference', required=True)
    product_id = fields.Many2one('product.product', string='Product', required=True)
    quantity = fields.Float(string='Quantity', required=True)
    price_unit = fields.Float(string='Unit Price', required=True)
    subtotal = fields.Float(string='Subtotal', compute='_compute_subtotal')

@api.depends('quantity', 'price_unit')
def _compute_subtotal(self):
    for line in self:
        line.subtotal = line.quantity * line.price_unit

@api.onchange('order_line')
def _onchange_order_line(self):
    total_amount = sum(line.subtotal for line in self.order_line)
    self.total_amount = total_amount

total_amount = fields.Float(string='Total Amount', compute='_compute_total_amount')

@api.depends('order_line.subtotal')
def _compute_total_amount(self):
    for order in self:
        order.total_amount = sum(line.subtotal for line in order.order_line)

<record id="view_order_form" model="ir.ui.view">
    <field name="name">sale.order.form</field>
    <field name="model">sale.order</field>
    <field name="arch" type="xml">
        <form string="Sale Order">
            <sheet>
                <group>
                    <field name="name"/>
                    <field name="total_amount" readonly="1"/>
                </group>
                <notebook>
                    <page string="Order Lines">
                        <field name="order_line">
                            <tree string="Order Lines">
                                <field name="product_id"/>
                                <field name="quantity"/>
                                <field name="price_unit"/>
                                <field name="subtotal" readonly="1"/>
                            </tree>
                        </field>
                    </page>
                </notebook>
            </sheet>
        </form>
    </field>
</record>