Problem storing children of a MappedSuperClass

fsamir · **Joined:** Fri Jan 12, 2007 1:21 pm **Posts:** 2

Hi guys,

I have a problem with MappedSuperClass. My structure is similar to this:

This is the Super Class of all VOs.

Code:

@MappedSuperclass
public abstract class AbstractContent implements Serializable {
   
   @Id
   @GeneratedValue(strategy=GenerationType.AUTO)   
   protected Integer id;
@ManyToMany(cascade=CascadeType.ALL,fetch=FetchType.LAZY)
   @JoinTable(name = "content_comments",         
            joinColumns = { 
               @JoinColumn( name="content_id", referencedColumnName = "id"),
                 @JoinColumn( name="comment_id", referencedColumnName = "id") },
            inverseJoinColumns = @JoinColumn( name="comment_id")
   )   
   protected List<CommentVo> comments = new ArrayList<CommentVo>();

These are the VOs.

Code:

@Entity
public class NewsVo extends AbstractContent
...

@Entity
public class CommentVo extends AbstractContent
...

@Entity
public class ArticleVo extends AbstractContent
...

And that is the problem:

Code:

                NewsVo news = new NewsVo();      
      news.setTitle("title");
      news.setShortText("shortText");
      news.setAdditionalText("additionalText");
      
      
      news.addComment(new CommentVo("Comment 1", "text 1"));
      news.addComment(new CommentVo("Comment 2", "text 2"));      
      newsDao.create(news);

And that is the error:

Code:

 JDBCExceptionReporter:logExceptions | Cannot add or update a child row: a foreign key constraint fails (`jnuke/content_comments`, CONSTRAINT `FKE856D2FAA2B9AD07` FOREIGN KEY (`content_id`) REFERENCES `[b]articles[/b]` (`id`))

Note that Hibernate3 is generating the table with a FK pointing to the table ARTICLES. But this association should be made with all sons of AbstractContent, not only with Article.

Code:

CREATE TABLE `jnuke`.`content_comments` (
   `id` INT DEFAULT '' NOT NULL,
   `comment_id` INT DEFAULT '' NOT NULL
) ENGINE=InnoDB;
...

ALTER TABLE `jnuke`.`content_comments` ADD CONSTRAINT `FKE856D2FA92F4FB81` FOREIGN KEY (`id`)
   REFERENCES `jnuke`.`articles` (`id`);

So, when I try to store a News with comments an error occours, because the relationship in the database is between Articles and comments.
If I remove the ArticleVo from teh soruce code, the hibernate will use another aleatory table in the relationship (FK).

Any ideas?

emmanuel · **Posted:** Sun Jan 21, 2007 6:54 pm

interesting, what happens if you get rid of the FK constraints (manually) and execute your code?
Is it getting allright?

emmanuel · **Posted:** Sun Jan 21, 2007 6:55 pm

ah forget what I've said, what you need to do is map AbstractContent as @Entity @Inheritence(strategy=TABLE_PER_CLASS) and leave it abstract (as it is)

fsamir · **Joined:** Fri Jan 12, 2007 1:21 pm **Posts:** 2

Hi Emmanuel,

Using TABLE_PER_CLASS everything works fine, but all of my entities will be merged into a single table. And, I can't do that because I have a lot of specializations of AbstractContent. It would be a huge and confuse table.

I would like to use a solution where the discriminator was stored in the intermediate table. For exempla:

Code:

Table content_1 (content_id, filed_1, ...);

Table content_2 (content_id, filed_x, ...);

Table Comment(comment_id, fileds...)

table content_comments(content_id, comment_id, discriminator)

Is that possible?

rhodespc · **Joined:** Mon Nov 03, 2003 1:07 am **Posts:** 14

I just upgraded to the latest hibernate annotations/hibernate core and was doing what you were doing.... While it worked in earlier versions, currently it does not work.

In my research, you can only do mapping of associations to Entities (@Entity) Only simple properties can be used in a @MappedSuperClass, not associations.

I found the MappedSuperClass to be of limited use with the inablility to map any associations in it.

Phillip

emmanuel · **Posted:** Fri Feb 02, 2007 5:43 pm

I would say you're wrong, but if you can create a minimal running test case involving 2 entities, post it to JIRA