我如何使用Django将其他模型字段添加到默认auth_user模型

Question

I'm new to Django. I need to include an extra model fields in my User Model (auth_user table in the database) as well as i want to include ForeignKey fields also inside auth_user

i have four models classes like Semestertype, Programtype, Programchoice:

import datetime
from django.utils import timezone

from django.db import models
from django.contrib.auth.models import User
from django.db.models.signals import post_save

from django.contrib.auth.models import AbstractUser

class Semestertype(models.Model):
value = models.CharField(max_length=100, null=True, blank=True)

class Meta:
    db_table = 'semestertype'


class Programtype(models.Model):
value = models.CharField(max_length=100, null=True)

class Meta:
    db_table = 'programtype'

class Programchoice(models.Model):
value = models.CharField(max_length=100, null=True, blank=True)

class Meta:
    db_table = 'programchoice'

I included Semestertype , Programtype, Programchoice models in my auth_user models using AbstractUser like below

class User(AbstractUser):
   semestertype = models.ForeignKey(Semestertype, on_delete=models.CASCADE,null=True, blank=True)
   programtype = models.ForeignKey(Programtype, on_delete=models.CASCADE,null=True, blank=True)
   programchoice = models.ForeignKey(Programchoice, on_delete=models.CASCADE,null=True, blank=True)
   filenumber = models.CharField(null=True, max_length=9, blank=True)
   personalemail = models.EmailField(max_length=254, blank=True)
   nameofbachelorsdegree = models.CharField(max_length=200, null=True, blank=True)

And This is my profile model:

class UserProfile(models.Model):
user = models.OneToOneField(User, on_delete=models.CASCADE,null=True, blank=True)
description = models.CharField(max_length=100,  default = '')
city = models.CharField(max_length=100, default = '')
phone = models.IntegerField(default=0)

def __str__(self):
    return self.user.username

def create_profile(sender, **kwargs):
if kwargs['created']:
    user_profile = UserProfile.objects.create(user=kwargs['instance'])
post_save.connect(create_profile, sender=User)

Finally i add my settings.py file like this:

AUTH_USER_MODEL = 'polls.User'# changes built-in user model to ours

I tried to adding ForeignKey fields and normal fields to auth_user and create profile form also but here i am getting error like below

AttributeError at /admin/polls/userprofile/add/
'NoneType' object has no attribute 'username'

I am new to Django i dont know where i did wrong pls help me anyone proper way to add extra fields to auth_user and add profile form

Thanks in advance...

Answer 1

The error is raising because of the __str__() method tries to return self.user.username but, some of the UserProfile instances don't have a related user instance, (because you defined it as null=True in the model)

So, change your __str__() method of UserProfile class as below,

class UserProfile(models.Model):
    # your fields

    def __str__(self):
        if self.user:
            return self.user.username
        return "no user related to this profile"

Or, change your UserProfile model as below and do migration,

class UserProfile(models.Model):
    user = models.OneToOneField(User, on_delete=models.CASCADE)  # <<< change is here
    description = models.CharField(max_length=100, default='')
    city = models.CharField(max_length=100, default='')
    phone = models.IntegerField(default=0)

    def __str__(self):
        return self.user.username