Help With Association Object Mapping

[Gregg Bolinger]

I don't expect a solution here because I know that the information has to be out there. I just don't know what it is called. I have three objects.

User
Role
Book

I need to map some sort of UserBookRole object. Book and User is a ManyToMany. A user can have different roles for different books. For example

User A -> Book 1 -> Author
User A -> Book 2 -> Editor
 
User B -> Book 3 -> Reviewer
User B -> Book 3 -> Author
User B -> Book 3 -> Editor

So what is this type of association called and where can I go to learn how to create the mappings correctly?

Thanks.

[Gregg Bolinger]

Many valued entity association. Alright, found it in my book. But would like some feedback.

@Embeddable
public class BookUser {
 
    @Parent
    private Book book;
 
    @ManyToOne
    @JoinColumn(name = "user_id", nullable = false, updatable = false)
    private User user;
 
    @ManyToOne
    @JoinColumn(name = "role_id", nullable = true)
    private Role role;
 
    // getters and setters
}

And then in my Book object I have this:

@CollectionOfElements
@JoinTable(name = "book_user", joinColumns = @JoinColumn(name = "book_id"))
private List<BookUser> bookUsers;

Does that look right?