Need help in django model - django

Question

I have written a model for my django project.
This is my model
from django.utils.translation import ugettext_lazy as _
from django.db import models
from django.utils.crypto import get_random_string
from django.db import models
from django.contrib.auth.models import(
BaseUserManager,
AbstractBaseUser,
PermissionsMixin,
)
def generate_vid():
"""Generates a vid for the users"""
not_unique = True
while not_unique:
vid = get_random_string(10, 'abcdefg0123456789')
if not User.objects.filter(v_id = vid).exists():
not_unique=False
return vid
class UserManager(BaseUserManager):
"""Model for user manager"""
def create_user(self, username, password, **params):
"""Create and return a user"""
u_type = params.pop('usertype','v')
params.update({'usertype':u_type})
p_username = params.pop('parent_username', 0)
if(u_type=='v'):
pass
else:
parent_id = User.objects.filter(username = p_username).values_list('v_id')
params.update({'parent_id': parent_id})
user = self.model(username=username, **params)
user.set_password(password)
user.save(using=self._db)
return user
def create_superuser(self, username, password, **params):
"""Create and return a user"""
params.setdefault('is_staff',True)
params.setdefault('is_superuser',True)
params.setdefault('is_active',True)
if params.get('is_staff') is not True:
raise ValueError(_('Superuser must have is_staff=True.'))
if params.get('is_superuser') is not True:
raise ValueError(_('Superuser must have is_superuser=True.'))
return self.create_user(username, password, **params)
class User(AbstractBaseUser, PermissionsMixin):
"""Models for user"""
v_id = models.CharField(
max_length=10,
default=generate_vid,
primary_key = True,
)
username = models.CharField(max_length=20, unique=True)
email = models.EmailField(blank=True, unique = True)
parent_id = models.ForeignKey('User', on_delete=models.SET_DEFAULT, default=0)
usertype = models.CharField(max_length=1, choices=[('f', 'family'), ('v', 'veteran')])
REQUIRED_FIELDS = ['usertype']
is_staff = models.BooleanField(default=False)
is_active = models.BooleanField(default=True)
USERNAME_FIELD = 'username'
objects = UserManager()
def __str__(self):
return self.username
Now I want to impose the condition while creating a user such that every time I provide usertype=f, and I provide a username(say username='Test")
the parent_id of that particular entry is automatically set as the v_id of the username provided.
The parent_id is a self referential foreignkey.
This is the error showing while testing the feature
File "/py/lib/python3.9/site-packages/rest_framework/serializers.py", line 205, in save
self.instance = self.create(validated_data)
File "/app/user/serializers.py", line 17, in create
return get_user_model().objects.create_user(**validated_data)
File "/app/base/models.py", line 39, in create_user
user = self.model(username=username, **params)
File "/py/lib/python3.9/site-packages/django/db/models/base.py", line 485, in __init__
_setattr(self, field.name, rel_obj)
File "/py/lib/python3.9/site-packages/django/db/models/fields/related_descriptors.py", line 215, in __set__
raise ValueError(
ValueError: Cannot assign "<QuerySet []>": "User.parent_id" must be a "User" instance.

Answer 1

I think you can try signals to set data after creating a user account. You can choose from several types, but I would recommend you focus on pre_save and post_save.
UPDATE
I wrote examples, but the website will probably better illustrate it. In general, there are quite a few signals, but the most commonly used are pre_save and post_save.
#2 UPDATE
Try use a first or latest. Details in documentation.
parent_id = User.objects.filter(username = p_username).first()