Objects in JPA ElementCollection as keys

Question

I have a class User that can have many loginNames:

@Entity
public class User {

  @ElementCollection
  private List<String> logins = new ArrayList<String>();

}

I want to ensure that each login is unique in the system when a user registers. When someone logs in the user object should be found by the login name. So the elements in the collection are some kind of (database) key.

How can I make them keys? How can I query efficiently? Would it be better to use a separate entity class for the login name?

Answer 1

What do you mean key? You can add "unique" constraints on CollectionTable to make them unique. If they are supposed to key across into some other table then the only sensible answer is to have a User Entity.