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

ForeignKey for one-to-many

📖 Scenario: You are building a simple blog application where each blog post can have many comments. You want to connect comments to their blog posts using Django's ForeignKey to show this one-to-many relationship.

🎯 Goal: Create two Django models: Post and Comment. Use a ForeignKey in Comment to link each comment to a single post. This will let you store multiple comments for each post.

📋 What You'll Learn

Create a Post model with a title field

Create a Comment model with a text field

Add a ForeignKey in Comment to Post with on_delete=models.CASCADE

Use related_name='comments' in the ForeignKey for easy access from Post

Follow Django model syntax and conventions

💡 Why This Matters

🌍 Real World

Blogs, forums, and social media apps often use one-to-many relationships to connect posts with comments or replies.

💼 Career

Understanding ForeignKey relationships is essential for backend developers working with Django to build relational data models.

1

Create the Post model

Create a Django model called Post with a single field title that is a CharField with max length 100.

Django

# Create the Post model with a title field
# Your code here

Need a hint?

Use models.CharField(max_length=100) for the title field inside the Post model.

2

Create the Comment model

Create a Django model called Comment with a single field text that is a TextField.

Django

from django.db import models

class Post(models.Model):
    title = models.CharField(max_length=100)

# Create the Comment model with a text field
# Your code here

Need a hint?

Use models.TextField() for the text field inside the Comment model.

3

Add ForeignKey to Comment

Add a ForeignKey field called post to the Comment model. It should link to the Post model, use on_delete=models.CASCADE, and have related_name='comments'.

Django

from django.db import models

class Post(models.Model):
    title = models.CharField(max_length=100)

class Comment(models.Model):
    text = models.TextField()
    # Add ForeignKey to Post here
    # Your code here

Need a hint?

Use models.ForeignKey(Post, on_delete=models.CASCADE, related_name='comments') for the post field.

4

Add __str__ methods for readability

Add a __str__ method to both Post and Comment models. For Post, return the title. For Comment, return the first 20 characters of text.

Django

from django.db import models

class Post(models.Model):
    title = models.CharField(max_length=100)

    # Add __str__ method here
    # Your code here

class Comment(models.Model):
    text = models.TextField()
    post = models.ForeignKey(Post, on_delete=models.CASCADE, related_name='comments')

    # Add __str__ method here
    # Your code here

Need a hint?

Define __str__ methods to return self.title for Post and self.text[:20] for Comment.