Using signals for two models both inheriting from User in Django - django

Question

Suppose we have two models that have signal to the User model:
from django.db import models
from django.contrib.auth.models import User
from django.db.models import signals
class Company(User):
name = models.CharField(null=True, blank=True, max_length=30)
if created:
Company.objects.create(
user_ptr_id=instance.id,
username=instance.username,
password=instance.password,
email=instance.email,
first_name=instance.first_name,
last_name=instance.last_name,
is_active=instance.is_active,
is_superuser=instance.is_superuser,
is_staff=instance.is_staff,
date_joined=instance.date_joined,
)
signals.post_save.connect(
create_company, sender=User, weak=False, dispatch_uid="create_companies"
)
class Individual(User):
name = models.CharField(null=True, blank=True, max_length=30)
def create_job_seeker(sender, instance, created, **kwargs):
"""
:param instance: Current context User instance
:param created: Boolean value for User creation
:param kwargs: Any
:return: New Seeker instance
"""
if created:
'''
we should add a condition on whether the Company uses the same username
if true, then, we must not create a JobSeeker and we would disable the account using
Firebase Admin
'''
JobSeeker.objects.create(
user_ptr_id=instance.id,
username=instance.username,
password=instance.password,
email=instance.email,
first_name=instance.first_name,
last_name=instance.last_name,
is_active=instance.is_active,
is_superuser=instance.is_superuser,
is_staff=instance.is_staff,
date_joined=instance.date_joined,
)
signals.post_save.connect(
create_job_seeker, sender=User, weak=False, dispatch_uid="create_job_seekers"
)
Now, each time a User is created we should be allowed to extend it through both Individual and Company models. But, I want to prohibit the usage of both objects. User can either have a Company or an Individual object to be edited not both. Should I override the save method such as this:
def save(self, *args, **kwargs):
if not Company.objects.filter(username=self.username).exists():
super(Model, self).save(*args, **kwargs)
else:
raise 'Some error'
Or should I add a condition on the created method such as this:
...
if created and Company.objects.filter(username, self.username).exists() == False:
Company.objects.create(
...
Which approach is better? And is there another approach that you might suggest?

Answer 1

Signals, for most cases, I believe are the best way to handle sharing data between models assuming the CRUD for each related model isn't done together. So post_save, pre_save, post_delete, pre_delete and so are typically the best way to go about handling data that any given model instance relies on. This can be true about manipulating model data after a save. Signals were designed specifically for this reason. The other great thing about signals is you can connect them throughout your project and not necessarily just where the Model is defined. Just import the model and the signal you want to connect to it and bam!
How to use signals? follow django's documentation here. it's very simple
https://docs.djangoproject.com/en/4.0/topics/signals/