Custom user model with AbstractUser in Django - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What is the output of accessing the custom field?

Given this custom user model extending AbstractUser, what will be the output of printing user.phone_number after creating a user with phone number '123-456-7890'?

Django

from django.contrib.auth.models import AbstractUser
from django.db import models

class CustomUser(AbstractUser):
    phone_number = models.CharField(max_length=15, blank=True)

# Assume user is created as:
user = CustomUser.objects.create(username='testuser', phone_number='123-456-7890')
print(user.phone_number)

A 123-456-7890

B '' (empty string)

C null

D Raises AttributeError

💡 Hint

Think about how model fields store data and how you access them.

The custom field phone_number is a CharField and stores the string '123-456-7890'. Accessing user.phone_number returns this string.

📝 Syntax

intermediate

Which option correctly defines a custom user model with AbstractUser?

Select the code snippet that correctly defines a custom user model by extending AbstractUser and adding a required 'birth_date' field.

A

class CustomUser(AbstractUser):
    birth_date = models.DateField(null=True, blank=True)

B

class CustomUser(AbstractUser):
    birth_date = models.DateField(null=False, blank=False)

C

class CustomUser(AbstractUser):
    birth_date = models.DateTimeField()

D

class CustomUser(AbstractUser):
    birth_date = models.CharField(max_length=10)

💡 Hint

A required date field should not allow null or blank values.

Option B correctly uses DateField with null=False and blank=False to make birth_date required. Other options either allow null/blank or use wrong field types.

🔧 Debug

advanced

Why does the custom user model cause a migration error?

Given this custom user model code, why does running python manage.py makemigrations raise an error about 'AUTH_USER_MODEL'?

Django

from django.contrib.auth.models import AbstractUser
from django.db import models

class CustomUser(AbstractUser):
    nickname = models.CharField(max_length=30, blank=True)

# settings.py missing AUTH_USER_MODEL = 'app.CustomUser'

A Because 'AUTH_USER_MODEL' is not set in settings.py to 'app.CustomUser', Django can't detect the custom user model.

B Because AbstractUser cannot be extended with new fields.

C Because the nickname field is missing a default value.

D Because the CustomUser class must inherit from AbstractBaseUser, not AbstractUser.

💡 Hint

Check your settings.py configuration for custom user models.

Django requires setting AUTH_USER_MODEL in settings.py to the custom user model path. Without it, migrations fail.

❓ state_output

advanced

What is the value of user.is_staff after creation?

Consider this custom user model extending AbstractUser. After creating a user with is_staff=false, what is the value of user.is_staff?

Django

from django.contrib.auth.models import AbstractUser

class CustomUser(AbstractUser):
    pass

user = CustomUser.objects.create(username='stafftest', is_staff=False)
print(user.is_staff)

A Raises ValueError

B True

C None

D False

💡 Hint

AbstractUser has is_staff field defaulting to False.

The is_staff field defaults to False and setting it explicitly to False keeps it False.

🧠 Conceptual

expert

Which statement about custom user models with AbstractUser is true?

Select the true statement about extending AbstractUser for a custom user model in Django.

A Django automatically detects custom user models without any settings changes.

B You must override the USERNAME_FIELD attribute when extending AbstractUser.

C Extending AbstractUser allows adding fields without redefining authentication methods.

D You cannot use AbstractUser if you want to add any new fields to the user model.

💡 Hint

Think about what AbstractUser provides compared to AbstractBaseUser.

AbstractUser includes default authentication methods and fields. Extending it lets you add fields easily without redefining authentication.