Database query optimization with select_related in Django - Mini Project: Build & Apply

Database query optimization with select_related

📖 Scenario: You are building a simple Django app to display a list of books with their authors. Each book has one author. You want to show the book title and the author's name efficiently.

🎯 Goal: Learn how to optimize database queries in Django by using select_related to fetch related author data along with books in a single query.

📋 What You'll Learn

Create Django models for Author and Book with a foreign key relationship

Write a query to get all books

Add a variable to hold the optimized query using select_related

Use the optimized query in a Django view to fetch books with authors efficiently

💡 Why This Matters

🌍 Real World

Optimizing database queries is important in real apps to make pages load faster and reduce server load.

💼 Career

Knowing how to use select_related is a key skill for Django developers to write efficient, scalable web applications.

1

Create Django models for Author and Book

Create two Django models: Author with a name field, and Book with a title field and a foreign key author to Author.

Django

# Define Author and Book models with the specified fields
# Your code here

Need a hint?

Use models.CharField for text fields and models.ForeignKey for the relationship.

2

Write a query to get all books

Write a Django query to get all Book objects and assign it to a variable called books.

Django

from django.db import models

class Author(models.Model):
    name = models.CharField(max_length=100)

class Book(models.Model):
    title = models.CharField(max_length=200)
    author = models.ForeignKey(Author, on_delete=models.CASCADE)

books = Book.objects.all()  # Your code here

Need a hint?

Use Book.objects.all() to get all book records.

3

Add a variable for optimized query using select_related

Create a variable called optimized_books that uses select_related('author') on Book.objects to fetch books with their authors in one query.

Django

from django.db import models

class Author(models.Model):
    name = models.CharField(max_length=100)

class Book(models.Model):
    title = models.CharField(max_length=200)
    author = models.ForeignKey(Author, on_delete=models.CASCADE)

books = Book.objects.all()

# Your code here

Need a hint?

Use select_related('author') to join author data in the same query.

4

Use optimized_books in a Django view

In a Django view function called book_list, return a render with template 'books.html' and context containing optimized_books as 'books'.

Django

from django.shortcuts import render

# Your code here

Need a hint?

Use render(request, 'books.html', {'books': optimized_books}) to pass data to the template.