Question

我启动了车队应用程序，并在模型相关文件中创建了一些模型，我进行了模型层次结构，上面是我拥有汽车品牌，下面是与每个品牌相关的ForeignKey相关汽车模型，以及每个最终构成ID的汽车ID的ForeignKey汽车库存，称为“ CarPool类”，在此模型中，我的值是“ car_sale_status = models.BooleanField（default = False）”，我想实现的是每次我根据卖方的关联ForeignKey创建一个实例时自动将“ car_sale_status = models.BooleanField（default = False）”更新为True

请咨询

谢谢

class CarPool(models.Model):

    # Relationship Fields
    car_inventory = models.ForeignKey(
        'cardealer.CarTypes',
        on_delete=models.CASCADE, related_name="carpools", 
    )
    car_id = models.CharField(max_length=30,default="")
    car_location = GeopositionField()
    car_sale_status = models.BooleanField(default=False)


    YEAR_CHOICES = []


    for r in range(1980, (datetime.datetime.now().year+1)):
        YEAR_CHOICES.append((r,r))


    year_manufacture = models.IntegerField(('year_manufacture'), choices=YEAR_CHOICES, default=datetime.datetime.now().year)


    def __str__(self):
        return self.car_id

    def __unicode__(self):
        return self.car_inventory

class CustomerBuyer(models.Model):

    buyer_car_buy = models.ForeignKey(
        'cardealer.CarPool',
        on_delete=models.CASCADE, related_name="customer_buyer",default='0'
    )
    buyer_private_name = models.CharField(max_length=80,default='')
    buyer_family_name = models.CharField(max_length=80,default='')
    buyer_private_id = models.IntegerField(default=0)
    transaction_date = models.DateTimeField(default=datetime.datetime.now())
    transaction_amount = models.IntegerField(default=0)




    def __str__(self):
        return self.buyer_private_name + ' '+ self.buyer_family_name

    def __unicode__(self):
        return self.buyer_private_name + ' '+ self.buyer_family_name

Answer 1

如果我对您的理解正确，只需扩展“保存”方法

class CustomerBuyer(models.Model):

    buyer_car_buy = models.ForeignKey(
        'cardealer.CarPool',
        on_delete=models.CASCADE, related_name="customer_buyer",default='0'
    )
    buyer_private_name = models.CharField(max_length=80,default='')
    buyer_family_name = models.CharField(max_length=80,default='')
    buyer_private_id = models.IntegerField(default=0)
    transaction_date = models.DateTimeField(default=datetime.datetime.now())
    transaction_amount = models.IntegerField(default=0)

    def __str__(self):
        return self.buyer_private_name + ' '+ self.buyer_family_name

    def __unicode__(self):
        return self.buyer_private_name + ' '+ self.buyer_family_name

    def save(self, *arg, **kwargs):
        super(CustomerBuyer, self).save(*args, **kwargs)
        self.buyer_car_buy.car_sale_status = True
        self.buyer_car_buy.save()

从与外键相关的另一个模型实例创建时更新模型字段

1 个答案: