👀 Views: 0 💬 Answers: 1 📅 Created: 2025-07-05

django orm prefetch_related Python

I'm attempting to set up I've hit a wall trying to I've been working on this all day and Hey everyone, I'm running into an issue that's driving me crazy... I tried several approaches but none seem to work... I'm working with an scenario with Django 4.1 where I'm trying to optimize a query with `prefetch_related` and complex filters but it's not limiting the QuerySet as expected. I have two models, `Author` and `Book`, where each author can have multiple books. I want to get all authors and prefetch only the books that were published after 2020. Here's what I've tried: ```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) published_date = models.DateField() ``` I wrote the following query: ```python from django.db.models import Prefetch, Q recent_books = Book.objects.filter(published_date__year__gt=2020) authors_with_recent_books = Author.objects.prefetch_related(Prefetch('books', queryset=recent_books)) ``` However, when I iterate through the authors and their books, I'm still seeing all books for each author, not just those published after 2020. The expected behavior is that only books published after 2020 should be prefetched. I also tried using `.annotate()` to check the count of recent books but that didn't help narrow down the prefetched result. The related query seems to ignore the filtering I applied. I even checked for issues in the database connections and caching layers which could be affecting it. Is there something I'm missing in the setup or a different approach I should take to achieve this? Any help would be greatly appreciated! I'm working on a application that needs to handle this. What am I doing wrong? I recently upgraded to Python 3.11. Thanks for taking the time to read this! I'm developing on Windows 11 with Python. I'm coming from a different tech stack and learning Python.