If you're not able to quickly answer it, I'd put it where you feel like you'd first look for it (where it feels natural) and move on - don't try to optimize too

If you're not able to quickly answer it, I'd put it where you feel like you'd first look for it (where it feels natural) and move on - don't try to optimize too early. The correct answer is going to depend heavily on what your app is doing, how it's structured, etc, so providing a good answer from an HN comment is going to be really hard. It's ok to be "wrong", just make sure you're consistently wrong so when you need to refactor it's not so bad. Eventually the answer will become clear...and if it never does, you probably made the right choice and saved a lot of time :) FWIW, https://www.django-rest-framework.org/api-guide/serializers/ https://www.django-rest-framework.org/api-guide/serializers/ might be helpful - but DRF is also a lot to take in if you're not already comfortable with Django.