Creating django models in the right way - django

Question

I have django models as follows :
class Type(models.Model):
limit = models.IntegerField()
name = models.CharField(max_length=50)
default = models.BooleanField()
def __str__(self):
return self.name
class Subscription(models.Model):
started = models.DateField()
type = models.OneToOneField(Type)
def __str__(self):
return self.type.name
class Member(models.Model):
user = models.ForeignKey(to=User)
number = models.CharField(max_length=10)
address = models.CharField(max_length=255)
postcode = models.CharField(max_length=10)
city = models.CharField(max_length=100)
active = models.BooleanField()
subscription = models.OneToOneField(Subscription, on_delete=models.CASCADE)
def __str__(self):
return self.name
Thus, member and subscription need to be OneToOneField relation, and subscription and type also OneToOneField relation.
But I want that member gets subscription of type default=true, if he creates a new account.
This is maybe not the question as it should be, but however, I would like to hear advice.
Thanks.

Answer 1

There are generally two options:
Attach some function to Member post_save signal, in function create appropriate instances if it was called with created=True:
from django.db.models.signals import post_save
from django.dispatch.dispatcher import receiver
#receiver(post_save, sender='myapp.Member')
def create_default_subscription(sender, instance, created, raw, using, update_fields):
if created:
<here create your subscription>
Override Member.save() method and create appropriate instances if self.pk is None.
def save(self, *args, **kwargs):
if self.pk is None:
<here create your subscription>
super().save(*args, **kwargs)
In both cases, you need to remember to associate created Subscription with your new Member.