Validattion in Domain layer Clean Architucture

Question

Im working on a API. In the domain layer, I have a method Public UserModel GetUser(int id)

. If the user is not found i want to return a 404. the issue is im supposed to return a UserModel how is validations done in the domain layer in Clean Architecture?
If i validate everything in controller i could get away with it just fine, but how can it be done in the Domain Layer?

Answer 1

You would have a class that's in the Models folder the controller calls the method on the class.