@ManyToMany problem and relations between several classes

brondsem · **Joined:** Tue May 25, 2004 9:56 am **Posts:** 19

With only one HistoryEntry, one EForm, one EFormConf, and a few EFormConf approvers and admins; I get around 40 history entries listed for the one form. When my code creates and saves the objects, the database has the proper data, but when it loads it and I display it there are far too many HistoryEntries

Hibernate version: 3.1.1, annotations 3.1beta8

Mapping documents:

Code:

@Entity
public class HistoryEntry implements Serializable {
   @Id
   @GeneratedValue(strategy=GenerationType.IDENTITY)
   protected long id;

   @ManyToOne(cascade = CascadeType.ALL)
   @JoinColumn(name="eform", insertable = false, updatable = false)
   protected EForm eform;

   protected String action;
   ...
}


@Entity
@Inheritance(strategy = InheritanceType.JOINED)
public class EForm implements Serializable {
   @Id
   @GeneratedValue(strategy=GenerationType.IDENTITY)
   protected long id;

   @ManyToOne
   protected EFormConf conf;
   
   @OneToMany(cascade=CascadeType.ALL, fetch = FetchType.EAGER)
   @JoinColumn(name="eform")
   @OrderBy("datetime")
   protected List<HistoryEntry> history = new ArrayList<HistoryEntry>();

   @Enumerated(EnumType.STRING)
   protected Status status = Status.DRAFT;

   @ManyToOne
   protected Person creator;
   ...
}

@Entity
public class EFormConf implements Serializable {
   
   @Id
   @GeneratedValue(strategy=GenerationType.IDENTITY)
   protected long id;
   
   @Column(unique = true)
   protected String name;

   @ManyToMany(fetch = FetchType.EAGER, cascade = CascadeType.ALL)
   @JoinTable(name="tblEFormConfApprovers")
   @IndexColumn(name = "approval_order", base=1)
   protected List<Person> approvers = new ArrayList<Person>();


   @ManyToMany(fetch = FetchType.EAGER, cascade = CascadeType.ALL)
   @JoinTable(name="tblEFormConfAdmins")
   protected List<Person> admins = new ArrayList<Person>();
   ...
}

Code between sessionFactory.openSession() and session.close():

Using spring hibernate support, I do:

Code:

form = getHibernateTemplate().get(MyForm.class, key);

where MyForm extends EForm, and key is a long

And then iterate through the HistoryEntries of

Code:

getForm().getHistory()

Name and version of the database you are using: MSSQL Server 8.0

The generated SQL (show_sql=true):

It's huge, joining between all tables. Our "Person" table has dozens of columns and is joined to several times.

emmanuel · **Posted:** Mon Jan 30, 2006 9:56 am

Do not eagerly fetch more than one collection per reultset or use Set Collection (is not involving a bag semantic)

brondsem · **Joined:** Tue May 25, 2004 9:56 am **Posts:** 19

emmanuel wrote:

Do not eagerly fetch more than one collection per reultset or use Set Collection (is not involving a bag semantic)

Thanks. I am not able to use lazy loading at this point (I'm working on it, but using a portlet environment is making it difficult) so I'll see what I can do.

Is this a bug, or an inherent limitation of eager loading?

emmanuel · **Posted:** Mon Jan 30, 2006 1:19 pm

it's a inherent limitation of using the bag semantic twice in a single resultset

brondsem · **Joined:** Tue May 25, 2004 9:56 am **Posts:** 19

emmanuel wrote:

it's a inherent limitation of using the bag semantic twice in a single resultset

Is there documentation for this?

I changed all my bag semantics to list or set semantics, but with the same results. Is it okay to have multiple collections using the list semantic?

emmanuel · **Posted:** Tue Jan 31, 2006 6:09 am

In the doc, there is a table summarizing how to do List semantc, have a look. I'm pretty sure you did not set the @IndexColumn

brondsem · **Joined:** Tue May 25, 2004 9:56 am **Posts:** 19

emmanuel wrote:

In the doc, there is a table summarizing how to do List semantc, have a look. I'm pretty sure you did not set the @IndexColumn

Yes, I've seen that table. I did try changing that List to a Set, so now I don't have any bag semantics. Does the limitation apply only to bag semantics?

emmanuel · **Posted:** Wed Feb 01, 2006 4:56 am