Retrieve related models

models.py

from django.db import models

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

    def __str__(self):
        return self.name

class Book(models.Model):
    title = models.CharField(max_length=100)
    author = models.ForeignKey(Author, on_delete=models.CASCADE, related_name='book_set')

    def __str__(self):
        return self.title

Retrieve related models

Here is how you can retrieve related models in Django ORM.

from myapp.models import Author, Book

famous_author = Author.objects.get(name='J.K. Rowling')
famous_books = famous_author.book_set.all()

this will execute the 2 queries to get the author and the books related to the author

Prefetch related models

If you want to reduce the number of queries you can use the prefetch_related method

from myapp.models import Author, Book

famous_author = Author.objects.prefetch_related('book_set').get(name='J.K. Rowling')
famous_books = famous_author.book_set.all()