Problem binding to domain layer POJOs

[klr8]

The Spring data binding system allows you to bind servlet request data to any command object, e.g. a POJO from your domain layer. However, I'm having a problem with this.

I have the following simple POJO User entity:

public class User extends Entity {
  private String userName;
  private Organization organization;

  //default constructor for use by Spring binding, Hibernate, ...
  public User() {
  }

  public User(String userName) {
    this.userName=userName;
  }

  //getters and setters omitted

  public void setLinkedOrganization(Organization org) {
    org.addUser(this);
  }

  public boolean equals(Object obj) {
    if (obj==this) return true;
    if (obj==null) return false;
    if (obj.getClass()!=this.getClass()) return false;
    User other=(User)obj;
    return this.getUserName().equals(other.getUserName());
  }

  public int hashCode() {
    return getUserName().hashCode();
  }
}

As you can see it uses the userName to determine equality. It also has a bidirectional associated with the Organization entity, so Organization has a method:

public class Organization extends Entity {
  private Set users=new HashSet();

  ...

  public void addUser(User user) {
    if (user.getOrganization()!=null) {
      user.getOrganization().removeUser(user);
    }
    user.setOrganization(this);
    users.add(user);
  }
}

The problem I now have is that when the ServletRequestDataBinder pushes in the Organization object when populating a new User in the CreateUserController, the userName has not yet been set! As a result the equals() method will throw a NullPointerException when the user is added to the "users" set of the organization (using users.add(user) in the code above).

Is there something stupid I'm doing here? How can I fix this while still using the ServletRequestDataBinder to bind to my domain layer POJO? I don't want to create a dummy DTO just to bind to and manually doing all the binding also seems clumsy!

Erwin

[cwilkes]

Are you cascading your changes between User and Organization? If so that should take care of the relationship so you don't have to do that step of removing a user from an organization.

I'm not sure what

that when the ServletRequestDataBinder pushes in the Organization object when populating a new User in the CreateUserController

means. Are you creating a new user? If so that's the time where you want to set his name. After you've created the user and an organization to it and then save.