Hibernate many-to-one - bad usage?

Posted by DaveA on Stack Overflow See other posts from Stack Overflow or by DaveA
Published on 2010-04-05T20:33:47Z Indexed on 2010/04/05 20:43 UTC
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Just trying out Hibernate (with Annotations) and I'm having problems with my mappings. I have two entity classes, AudioCD and Artist.

@Entity
public class AudioCD implements CatalogItem {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private int id;

    private String title;

    @ManyToOne(cascade = { CascadeType.ALL }, optional = false)
    private Artist artist;
    ....
}

@Entity
@Table(uniqueConstraints = { @UniqueConstraint(columnNames = { "name" }) })
public class Artist {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private int id;

    @Column(nullable = false)
    private String name;
    .....
}

I get AudioCD objects from an external source. When I try to persist the AudioCD the Artist gets persisted as well, just like I want to happen. If I try persisting another different CD, but Artist already exists I get errors due to constraint violations.

I want Hibernate to recognise that the Artist already exists and shouldn't be inserted again. Can this be done via annotations? Or do I have to manage the persistence of the AudioCD and Artist seperately?

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