Question

In my JPA2/Hibernate application I have table USERS and matching entity User + DAO.

Now, I created view V_USERS, which contains filtered data from table USERS.

Can I reuse entity User to query data from this view ?

Answer 1

No you can’t. You can map two different classes into the same table but not the other way around.

The reason for this limitation is simple, how would JPA provider knew which table do you have in mind in the following query:

em.createQuery("SELECT u FROM User u");

However you might want to create a base class AbstractUser with all properties and have to empty subclasses: User and for instance VUser. The latter two classes will have a mapping to different tables/views. See MappedSuperclass and an example there.

@MappedSuperclass
public abstract class AbstractUser {
    //all your columns/JPA mapping go here
}

@Entity
@Table(name="USERS")
public class User extends AbstractUser {}

@Entity
@Table(name="V_USERS")
public class VUser extends AbstractUser {}