根据某些操作更新库存中的产品数量

Question

您好，我在one2many字段中添加了车辆备件的表格，我想根据订购数量修改库存中的产品数量，以便

  

可用数量=可用数量-订购数量

约束与第一个条件匹配，但与其他情况不匹配。

class One2manyProductLine(models.Model):
    _inherit = 'fleet.vehicle.log.services'

    custom_field = fields.One2many("product.line.details", "new_field", string="Test", copy=True, auto_join=True)


class ProductLineDetails(models.Model):
    _name = 'product.line.details'

    product_id = fields.Many2one('product.product', string="Product")
    avail_qty = fields.Float(related='product_id.qty_available', string="Quantity")
    exact_cost = fields.Float(related='product_id.standard_price')
    product_desc = fields.Text()
    ordered_qty = fields.Float(store=True)
    total = fields.Float(compute='_compute_total')
    new_field = fields.Many2one('fleet.vehicle.log.services')

     @api.constrains('ordered_qty')
    def _check_ordered_qty(self):
        for rec in self:
            if rec.ordered_qty > rec.avail_qty:
                raise ValidationError("There is no enough amount in stock")
            else:
                self.avail_qty = rec.avail_qty - rec.ordered_qty