👀 Views: 412 💬 Answers: 1 📅 Created: 2025-06-05

django orm prefetch_related Python

I've hit a wall trying to I've looked through the documentation and I'm still confused about I'm sure I'm missing something obvious here, but I'm working on a project and hit a roadblock. I'm working with an scenario with Django's ORM where the prefetch related queries seem to have unexpected results. I have a model structure like this: ```python class Author(models.Model): name = models.CharField(max_length=100) class Book(models.Model): title = models.CharField(max_length=100) author = models.ForeignKey(Author, related_name='books', on_delete=models.CASCADE) ``` When I use `prefetch_related` to fetch books along with authors, I notice that calling the prefetch on a queryset leads to unexpected duplications in the results. For example: ```python from django.db.models import Prefetch authors = Author.objects.prefetch_related('books').all() for author in authors: print(author.name) for book in author.books.all(): print(book.title) ``` When I execute this code, I get the output of duplicate author entries in my console. I expected each author to only appear once, followed by their respective books. However, I'm seeing repeated author names with their associated books stacked under them multiple times. I also tried using `distinct()` like this: ```python authors = Author.objects.prefetch_related('books').distinct().all() ``` But it didn't solve the scenario. I'm running Django 3.2.5 and PostgreSQL as my backend. I suspect it might have something to do with how prefetching works with related managers in Django, but I need to pinpoint the exact cause. Has anyone experienced similar behavior or does anyone know how to correctly use `prefetch_related` to avoid duplication in results? I'm working on a application that needs to handle this. My development environment is Linux. Any help would be greatly appreciated! Is there a simpler solution I'm overlooking?