How to set a field constant in a django model - django

Question

I have a custom user model and a company model:
class User(AbstractUser):
username = None
email = models.EmailField(_('email address'), unique=True)
USERNAME_FIELD = 'email'
REQUIRED_FIELDS = []
objects = UserManager()
company = models.ForeignKey(
Company, null=True, blank=False, on_delete=models.SET_NULL)
class Company(models.Model):
company_name = models.CharField(
default='', max_length=128, blank=True, null=True)
In settings.py I also have a customer_name constant:
CUSTOMER_NAME = os.environ.get('CUSTOMER_NAME')
How can I add a condition in my user model so that if the user is_staff boolean is TRUE then the company_name is fixed to be the CUSTOMER_NAME constant?

Answer 1

Do you have two options:
1) Option 1: Overriding save ( Overriding predefined model methods )
from django.conf import settings
class User(AbstractUser):
username = None
...
company = models.ForeignKey(
Company, null=True, blank=False, on_delete=models.SET_NULL)
def save(self, *args, **kwargs):
if self.is_staff:
#company_name = os.environ.get('CUSTOMER_NAME')
company_name = settings.CUSTOMER_NAME
target = Company.objects.get_or_create( company_name = company_name )
serf.company = target
super().save(*args, **kwargs) # Call the "real" save() method.
2) Option 2: Using pre-save signal:
from django.db.models.signals import pre_save
from django.dispatch import receiver
from django.conf import settings
#receiver(pre_save, sender=User)
def my_handler(sender, **kwargs):
if self.is_staff:
#company_name = os.environ.get('CUSTOMER_NAME')
company_name = settings.CUSTOMER_NAME
target = Company.objects.get_or_create( company_name = company_name )
serf.company = target

Answer 2

The best approach to do this is to override the save function of your model like this:
class User(AbstractUser):
username = None
email = models.EmailField(_('email address'), unique=True)
USERNAME_FIELD = 'email'
REQUIRED_FIELDS = []
objects = UserManager()
company = models.ForeignKey(
Company, null=True, blank=False, on_delete=models.SET_NULL)
def save(self, force_insert=False, force_update=False, using=None,
update_fields=None):
if self.instance.id is None and self.is_staff is True: # instance.id is None indicates the instance is new and not an existing one
constant_company = Company('company_name'=CUSTOMER_NAME) # You could also search for an existing company with the CUSTOMER_NAME
constant_company.save()
self.company = constant_company
super().save(force_insert, force_update, using, update_fields)
This way will ensure you each time a staff user is saved no matter where a company with your constant name will be linked to it.