Best practice for hierarchical DTOs?

Question

Hi!
Can someone tell me the best practice for hierarchical DTOs?
Use case: I've got a User object which holds one Folder object, which in turn holds a Set of Folder objects (children).
class User {
  Folder rootFolder;
class Folder {
Set children;
}Normally, I'd fetch the user data with the help of a DAO from the database, copy the requested properties into a User-DTO, which will be transfered to the view. But what about the Folder objects?
Should I create a Folder-DTO class and copy each Folder property into the respective DTO object - in other words: rebuild the whole hierarchy? Or is there a better solution?
Thanks a lot!
Walter

Answer 1

Normally, I'd fetch the user data with the help of a
DAO from the database, copy the requested properties
into a User-DTO, which will be transfered to the view.
But what about the Folder objects?
Should I create a Folder-DTO class and copy each
Folder property into the respective DTO object - in
other words: rebuild the whole hierarchy? Or is there
a better solution?It isn't recursive right?
So this is just a standard association.
How you handle it depends on usage.
As a guess perhaps you are thinking that you can only have one User DTO class. That isn't true. You can have several. For example one that contains the association and one that does not.
Or you have just one. And either it contains the association or you provide another mechanism that returns just the association given a specific instance of a User DTO (or some other identifier to the specific User.)