Когда в филды пишу просто 'user', рест говорит: Could not resolve URL for hyperlinked relationship using view name "user-detail". You may have failed to include the related model in your API, or incorrectly configured the lookup_field attribute on this field. И тут я ваще в шоке
Ты пробовал почитать туториал про Relationships & Hyperlinked APIs?