how to update ManyToManyField while an instance been created

user_13001893 0
Viewed 216

i want to to update field whenever an instance been created i tried signals but it seems complicate to ManyToManyField 

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)

i want to update active field in Imei model when MobileCustomer created !? i tried this in my CreateView form_valid

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

and it printed 0 ? how to make it work either using signals or update() whenever an instance created inside createview

signals many-to-many django-models django
4 Answers

lookup problem. mobile lookup to MobileStorage, then mobilecustomer lookup to 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)
user_134374510

I think the relationship you are looking for is: Imei > MobileStorage > SelectMobile > MobileCustomer. You can try like this:

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

post_save signal example:

@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)
user_26961650

Using .filter() will return a list. You want to use something like a .get() or the following get or 404 to get a single object. 

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

If you already have the object which is self.object you can use

imei = self.object
imei.active = False
imei.save()
user_69082040

i had to use m2m_changed signal look like this `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)
user_130018930
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