jpa, more then one primary key

Question

Hello,

I have an Article entity and an ArticleCode entity. Aritcle Code has Article as forgeing key but is has also a second and third primary key.

The example below isnt possible because Article isnt serializable. Any ideas?

Thanks, Ralph

@Entity public class Article {
@Id @GeneratedValue(strategy=GenerationType.TABLE) private Long id;

public Long getId() { return id; }

}

@Entity @IdClass(com.google.gwt.sample.stockwatcher.server.huflattich.ArticleCode.ComposedIdKey.class) public class ArticleCode {

@Id
@OneToOne
private Article article;

@Id
@Column(name="coding_system")
private String codingSystem;

@Id
private String code;

...

public static class ComposedIdKey implements Serializable {
    public Article article;
    public String codingSystem;
    public String code;

    public ComposedIdKey () { }

    public ComposedIdKey(Article article, String codingSystem, String code) {
     this.article = article;
        this.codingSystem = codingSystem;
        this.code = code;
    }

     ...
}

}

Answer 1

ohh, in google's BigTable it is impossible to have more then one primary key.