Question

how can I bind custom data to a user?
Eg: User logs in > can only see Lists / Items he created himself.

Do I have to make an Entity User objekt, and further make it contain a @OneToMany list with these objects?
Or what is the best approach for things like this in general?

Tyvm!

Answer 1

It’s common practise to have a User kind of entity if you have a system where a user can log in and has it’s own stuff.

Consider a Item class:

@Entity
public class Item {

    @NotNull
    @ManyToOne
    private User user;  // plus getter + setter

}

Then you get a list of items from a particular user:

String query = "SELECT i FROM Item i WHERE i.user = :user";
List<Item> items = entityManager.createQuery(query)
    .setParameter("user", user)  // where 'user' is the current user
    .getResultList;

And an example Bean in JSF:

public class ItemsBean implements Serializable {
    private User user;
    private List<Item> items;

    public User getUser() {
        if (user == null) {
            ExternalContext ctx = FacesContext.getCurrentInstance().getExternalContext();
            Principal principal = ctx.getUserPrincipal();
            user = ... // load user: username = principal.getName()
        }
        return user;
    }

    public List<Item> getItems() {
        if (items == null) {
            User user = getUser();
            List<Item> = ... // load items as shown above
        }
        return items;
    }
}