👀 Views: 2 💬 Answers: 1 📅 Created: 2025-06-08

django prefetch database queryset Python

I'm migrating some code and I'm not sure how to approach I'm following best practices but After trying multiple solutions online, I still can't figure this out... I have a Django application using version 3.2, and I'm experiencing unexpected behavior when prefetching related objects. I'm trying to retrieve a list of authors along with their published books using `Prefetch` to optimize database access. However, when I iterate through the pre-fetched books, it seems the queryset is being cached in a way that causes it to return stale data on subsequent requests. Here’s a simplified version of my code: ```python from django.db.models import Prefetch from .models import Author, Book class AuthorView(APIView): def get(self, request): authors = Author.objects.prefetch_related( Prefetch('book_set', queryset=Book.objects.filter(is_published=True)) ).all() for author in authors: print(f'Author: {author.name}') for book in author.book_set.all(): print(f' - Book: {book.title}') # This can return stale data return Response({'authors': authors}) ``` In this case, `book_set` should only contain published books, but when I modify the database and re-run this view, the previously fetched books sometimes show up again even though they've been unpublished. I’ve tried clearing the cache using `cache.clear()` before the query, but that doesn’t seem to help. Is there something specific about how `prefetch_related` works that I might be missing? Should I be using `select_related` instead? Any advice on ensuring the data returned is always fresh would be appreciated. My development environment is Ubuntu. How would you solve this? I'm working in a Ubuntu 22.04 environment. Thanks for any help you can provide! Is this even possible? Thanks, I really appreciate it! For context: I'm using Python on Windows 10. Am I missing something obvious?