How do I use joins in Django querysets?

How do I use joins in Django querysets?

In Django, you can use the select_related and prefetch_related methods to perform joins. select_related is used for single-valued relationships (like ForeignKey), while prefetch_related is for multi-valued relationships (like ManyToMany). Would you like an example?

Yes, please provide an example using select_related.

Sure! If you have a Book model with a ForeignKey to an Author model, you can do:

books = Book.objects.select_related('author').all()

This will fetch all books along with their authors in a single query.

What about using prefetch_related?

For prefetch_related, if you have a Author model with a ManyToMany relationship to a Genre model, you can do:

authors = Author.objects.prefetch_related('genres').all()

This will fetch all authors and their associated genres efficiently.