如何在创建实例时更新 ManyToManyField

Question

我想在创建实例时更新字段我尝试了 signals 但它似乎对 ManyToManyField

来说很复杂

class MobileCustomer(models.Model):
    customer = models.CharField(max_length=30)
    phone = models.CharField(max_length=13)
    mobile = models.ManyToManyField(MobileStorage,through='SelectMobile')

class SelectMobile(models.Model):
    mobile = models.ForeignKey(MobileStorage,on_delete=models.CASCADE)
    item = models.ForeignKey(MobileCustomer,on_delete=models.CASCADE)
    quantity = models.PositiveIntegerField(default=1)
    imei = models.ManyToManyField(Imei)

class MobileStorage(models.Model):
    mobile = models.ForeignKey(Mobile,on_delete=models.CASCADE)
    quantity = models.PositiveIntegerField()

class Mobile(models.Model):
    mobile_name = models.CharField(max_length=40,unique=True)

class Imei(models.Model):
    imei = models.CharField(max_length=15,verbose_name='IMEI',unique=True)
    mobile = models.ForeignKey(MobileStorage,on_delete=models.CASCADE)
    active = models.BooleanField(default=True)

我想在 MobileCustomer 创建时更新 Imei 模型中的活动字段！？我在 CreateView form_valid

中试过了

imei = Imei.objects.filter(selectmobile__item=self.object).update(active=False)
print(imei)

它打印了 0 ? 每当在 createview

中创建实例时，如何使用信号或 update() 使其工作

Answer 1

使用 .filter() 将 return 一个列表。您想使用 .get() 或以下 get 或 404 之类的东西来获取单个对象。

imei = get_object_or_404(Imei, pk=imei_id)
imei.active = False
imei.save()

如果您已经有了 self.object 的对象，您可以使用

imei = self.object
imei.active = False
imei.save()

Answer 2

查找问题。移动查找到 MobileStorage，然后移动查找到 MobileCustomer。

def form_valid(self, form):
  # self.object = None
  super().form_valid(form)
  # self.object = a instance of MobileCustomer
  imei = Imei.objects.filter(mobile__mobilecustomer=self.object).update(active=False)
  print(imei)

Answer 3

我想你要找的关系是：Imei > MobileStorage > SelectMobile > MobileCustomer。你可以这样尝试：

imei = Imei.objects.filter(mobile__selectmobile__item=self.object).update(active=False)
print(imei)

post_save 信号示例：

@receiver(post_save, sender=MobileCustomer)
def do_something(sender, instance, created, **kwargs):
    if created:
        imei = Imei.objects.filter(mobile__selectmobile__item=instance).update(active=False)
    print(imei)

Answer 4

我不得不使用像这样的 m2m_changed 信号 `def

def update_m2m(sender,instance,*args,**kwargs):
     Imei.objects.filter(pk__in=kwargs.get("pk_set")).update(active=False)
m2m_changed.connect(update_m2m,sender=SelectMobile.imei.through)

如何在创建实例时更新 ManyToManyField

how to update ManyToManyField while an instance been created

django

many-to-many

signals

django-models

查找问题。移动查找到 MobileStorage，然后移动查找到 MobileCustomer。