OneToOneField for one-to-one in Django - Mini Project: Build & Apply

OneToOneField for one-to-one

📖 Scenario: You are building a simple Django app to store user profiles. Each user has exactly one profile with extra information.

🎯 Goal: Create two Django models: User and Profile. Link them with a one-to-one relationship using OneToOneField.

📋 What You'll Learn

Create a User model with a username field

Create a Profile model with a bio field

Add a OneToOneField in Profile linking to User

Set on_delete=models.CASCADE for the OneToOneField

Use exact field and model names as specified

💡 Why This Matters

🌍 Real World

One-to-one relationships are common when you want to extend user information without changing the original user model.

💼 Career

Understanding OneToOneField is essential for Django developers building user profiles, settings, or linked data models.

1

Create the User model

Create a Django model called User with a single field username that is a CharField with max_length=30.

Django

# Create the User model with username field
from django.db import models

# Your code here

Need a hint?

Use class User(models.Model): and define username = models.CharField(max_length=30).

2

Create the Profile model with bio field

Add a Django model called Profile with a bio field that is a TextField.

Django

from django.db import models

class User(models.Model):
    username = models.CharField(max_length=30)

# Create the Profile model with bio field

# Your code here

Need a hint?

Define class Profile(models.Model): and add bio = models.TextField().

3

Add OneToOneField linking Profile to User

In the Profile model, add a OneToOneField called user that links to the User model with on_delete=models.CASCADE.

Django

from django.db import models

class User(models.Model):
    username = models.CharField(max_length=30)

class Profile(models.Model):
    bio = models.TextField()
    # Add OneToOneField user linking to User
    # Your code here

Need a hint?

Use user = models.OneToOneField(User, on_delete=models.CASCADE) inside Profile.

4

Add __str__ methods for better display

Add a __str__ method to both User and Profile models. For User, return self.username. For Profile, return f"Profile of {self.user.username}".

Django

from django.db import models

class User(models.Model):
    username = models.CharField(max_length=30)

    # Add __str__ method
    # Your code here

class Profile(models.Model):
    bio = models.TextField()
    user = models.OneToOneField(User, on_delete=models.CASCADE)

    # Add __str__ method
    # Your code here

Need a hint?

Define def __str__(self): in both models returning the specified strings.