Copy DTOs to aggregate (as defined by Eric Evans)

Question

Hello,
I have the following situation: Hand is an aggregate which consists of several fingers. Each finger can only belong to one hand. So hand is the aggregate root.
One could write:
package org.hand;
class Hand {
  private long id; //generated by hibernate when saving the entity to the db
  private List<Finger> fingers = new ArrayList<Finger>();
  public void addFinger() {
   this.fingers.add(new Finger());
  public List getFingers() {
   return Collections.unmodifiableList(this.fingers);
  public Finger getFinger(long fingerId) {
   // Code to find a Finger by its Id.
class Finger {
  private Long id;  //generated by hibernate when saving the entity to the db
  private Long someProperty;
  protected Finger() {super()};
  public void setProperty(long val) {...}
  public long getProperty()
  public Long getId() {...}
  public void setId(Long id) {...}
}Hand has the method addFinger() to avoid that one Finger is added to another hand. It also prevents that a Finger exits without a Hand.
Furthermore the client sends a list of FingerDTOs to the server in order to modify the fingers of a Hand.
class FingerDTO {
  private Long id;
  private Long someProperty;
  public void setProperty(long val) {...}
  public long getProperty()
  public Long getId() {...}
  public void setId(Long id) {...}
}The client can modify an existing finger by sending a FingerDTO with an existing ID and add new Fingers by sending a FingerDTO without Id.
All Fingers which are not included in that list will be deleted from the hand.
The code to handle the adding and modifyng could look like this:
     for (final FingerDTO dto : dtoList) {
          Finger finger
          if (dto.getId() != null) {
               finger = theHand.getFinger(dto.getId());
          } else {
               finger = theHand.addNewFinger();
          finger.setProperty(dto.getProperty());
     }How would you include the deleting of no longer existing Fingers, on order to have a meaningfull model? Would you build a list of all Finger which where send from the client and remove the others from the hand or is there a more meaningfull way to implement this?

Answer 1

ODCI is just like regular PL/SQL. So use whatever approach you would used when diagnosing problems in your other programs - DBMS_OUTPUT,PUT_LINE (aka the Devil's Debugger), stepping through in SQL Developer (or A.N.Other PL/SQL IDE) or using some other form of trace.
Cheers, APC
blog: http://radiofreetooting.blogspot.com