Scenario : User table contains 3 fields - UserID, UserName, UserAddress.
If I want to use the DAO pattern to create a new user then I would need UserBusinessObject, User(value object), UserDAO. Here's the code snippet:

public class UserBusinessObject {
   public addUser(String userName, String userAddress) {
      User user = new User();
      user.setUserAddress(userAddress);
      user.setUserName(userName);
      new UserDAO().create(user);
    }
    .....
}

public class User {
    //getters & setters for userName & userAddress
}

public class UserDAO {
   public User create(String userName, String userAddress) {
      //generate UserID
      //apply SQL to insert values into these 3 fields
      return new User(userID, userName, userAddress);
   }
   ....
}

As you see, I'm creating the User value object in the business object even though I do not have the userID. So basically the user value object is not really valid at this point! Is my assumption/implementation correct or wrong?

Thanks,

Poorav

If you do database stuff in your UserDAO.create() method, then you should get a hold of an userID also.

public User create(String userName, String userAddress)
{
  // 1. get a database connection
  // 2. get a unique userID for the to-be-created user
  // 3. insert userID, userName and userAddress to database
  return new User(userID, userName, userAddress);
}

If User Value Object was as below :

public class User {
  
  public User create(User userVO) {
    // 1. get a database connection
    // 2. get a unique userID for the to-be-created user
    // 3. insert userID, userName and userAddress to db
    return new User(userID, userName, userAddress);
  }
}

then could I have the following in the Business Object :

public class UserBusinessObject {
   public addUser(String userName, String userAddress) {
      User user = new User();
      user.setUserAddress(userAddress);
      user.setUserName(userName);
      new UserDAO().create(user);
    }
    .....
}

So basically I'm creating a User value object without the userID and passing it as a paramater to the UserDAO. So its only a partial object at that instant. Is that ok?