👀 Views: 2 💬 Answers: 1 📅 Created: 2025-06-05

django queryset prefetch_related many-to-many Python

I'm stuck on something that should probably be simple. I am trying to optimize a Django query using `prefetch_related` to fetch related models along with filtering conditions, but I'm working with unexpected results. I have a `Book` model and an associated `Author` model, where each book can have multiple authors. I want to retrieve books written by a specific author, along with all their respective co-authors, but my query seems to be returning extra authors that shouldn't be included. Here's a simplified version of my models: ```python class Author(models.Model): name = models.CharField(max_length=200) class Book(models.Model): title = models.CharField(max_length=200) authors = models.ManyToManyField(Author) ``` I am trying to execute the following query: ```python from django.db.models import Prefetch specific_author = Author.objects.get(name='John Doe') books = Book.objects.prefetch_related( Prefetch('authors', queryset=Author.objects.exclude(id=specific_author.id)) ).filter(authors=specific_author) ``` I expected to get a list of books along with authors excluding 'John Doe', but the output still includes 'John Doe' in the authors for each book. I have also tried using `.annotate()` and `.distinct()` but the results remain the same. Here’s the output I get for one of the books: ``` Book Title: "Great Adventures" Authors: ["John Doe", "Jane Smith"] ``` Even with the exclusion in `Prefetch`, 'John Doe' is still appearing. Can someone guide to understand why this is happening and what I can do to only return authors who are not 'John Doe' alongside the respective books? Am I misusing `prefetch_related` or is there a better way to achieve this? Any insights would be appreciated! I'm working on a web app that needs to handle this.