[jboss-user] [EJB 3.0] - Up-/Downcasting from objects with partial db-update

Hi, I´ve got two objects, that are extended from each other. For example they look like this: | @Entity | @Table(name = "users") | @Name("user") | @Scope(ScopeType.SESSION) | public class User implements Serializable { | | @Column(name = "create_date", nullable = false) | @Temporal(TemporalType.TIMESTAMP) | private Date createDate; | | @Length(min=6) | @Column(name = "password", nullable = false) | private String password; | | @Column(name = "name", nullable = false) | private String name; | | .... | } | | @Entity | @Table(name = "extendedUser") | @Name("publisher") | @Scope(ScopeType.SESSION) | public class ExtendedUser extends User implements Serializable { | | @Column(name = "upgrade_date", nullable = false) | @Temporal(TemporalType.TIMESTAMP) | private Date upgradeDate; | | .... | } | I´ve also got 2 tables. One holds all the attributes for the user and the other one holds only the additional attributes of the extendedUser all with the same primaryKey. What I would like to do now is to upcast my User to an ExtendedUser, so that it keeps all the values in the user-table and creates an entry in my extended-users table with all additional values of the extended object. When I simply upcast my object and try to persist it with an em.merge(extendedUser) I get an Exception because it tries to persist a completely new extendedUser, which is absolutely correct, because it should only add the additional values and not create a new entry. Is there a way to do an upcast/downcast and adding/deleting only the additional attributes of the inherited objects? Thanks for your help Thomas View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4005398#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...