Junior — Senior
How to get rid of N+1 queries in Django ORM
livecode
Task condition
It is necessary to improve the efficiency of database queries by avoiding unnecessary access to related models. The example below shows a simple schema with Author and Book models. The logic should be changed so that when displaying the author's name for a book, a separate query is not performed for each record.
from django.db import models
class Author(models.Model):
name = models.CharField(max_length=255)
class Book(models.Model):
name = models.CharField(max_length=255)
author = models.ForeignKey(Author, on_delete=models.CASCADE, related_name='books')
price = models.IntegerField(default=100)
all_books = Book.objects.all()
# Filtering books by authors
author_1_books = all_books.filter(author_id=1)
author_2_books = all_books.filter(author_id=2)
for book in all_books:
print(book.author.name)