Selection of objects with backreference

mbebil · **Joined:** Wed Mar 15, 2006 5:46 am **Posts:** 2

Hibernate version:
3.2.0 GA (JEMS Installer 1.2.0), 3.2.1 (JBoss 4.2.0CR1)

Full stack trace of any exception that occurs:
ClassNotFoundException: [Lorg.jboss.aop.Inteceptor
Could not find marshaller for data type ('null'). Trying to load from server (from my memory)

Name and version of the database you are using:
MySQL 5.0.37, ConnectorJ 5.0.5

JDK 1.6.0 U1

Hi all,

I wrote an enterprise application which run under JBoss 4.0.4 without any problems. Yesterday I started to port it to an newer release of JBoss AS/Hibernate.

I had some problems with the new bag semantic of Lists<T> and so I changed all occurences of OneToMany and ManyToMany to include @IndexColumn("idx_col_name"). Could compile and run without problems.

After porting of serverside code, I started to port my clientside (Swing Client) code to the new relevant libs from JBoss 4.0.5GA. Everything seemed to be ok. But after first start of the application, I run into seriouse problems:
1. When I loaded arrays of entity objects. Solved: JBoss remoting patch 1.4.6. (JDK 1.6 ClassLoader problem)
2. The next problem occured, when I wanted to load objects, which include lists of objects of its own class type:

Code:

import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;

import javax.persistence.CascadeType;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.ManyToOne;
import javax.persistence.OneToMany;

@Entity
public class OrganisationUnit implements Serializable {
   
   //    <node label="txtree.nodes.root.label" icon="home.png" desc="txtree.nodes.root.desc">
   
   @Id @GeneratedValue(strategy=GenerationType.AUTO)
   private long id;   
   
   @ManyToOne()   
   private OrganisationUnit parentUnit;
   
   @OneToMany(mappedBy="parentUnit", cascade=CascadeType.ALL, fetch=FetchType.EAGER)   
                @IndexColoumn(name="id")
   private List<OrganisationUnit> childUnits = new ArrayList<OrganisationUnit>();
   
   @OneToMany(mappedBy="organisationUnit", cascade=CascadeType.ALL, fetch=FetchType.EAGER)
                @IndexColoumn(name="id")
   private List<Function> functions = new ArrayList<Function>();
   
   private String label;
   private String icon;
   private String description;
   
   private boolean enabled = true;
   
   private boolean visible = true;
   
   private boolean expanded = false;

   private boolean displaySeparatorBefore = false;
   
   private boolean displaySeparatorAfter  = false;
   
   public List<OrganisationUnit> getChildUnits() {
      return childUnits;
   }
   
   public void setChildUnits(List<OrganisationUnit> childUnits) {
      this.childUnits = childUnits;
   }
   
   public String getDescription() {
      return description;
   }
   
   public void setDescription(String description) {
      this.description = description;
   }
   
   public boolean isDisplaySeparatorAfter() {
      return displaySeparatorAfter;
   }
   
   public void setDisplaySeparatorAfter(boolean displaySeparatorAfter) {
      this.displaySeparatorAfter = displaySeparatorAfter;
   }
   
   public boolean isDisplaySeparatorBefore() {
      return displaySeparatorBefore;
   }
   
   public void setDisplaySeparatorBefore(boolean displaySeparatorBefore) {
      this.displaySeparatorBefore = displaySeparatorBefore;
   }
   
   public boolean isEnabled() {
      return enabled;
   }
   
   public void setEnabled(boolean enabled) {
      this.enabled = enabled;
   }
   
   public List<Function> getFunctions() {
      return functions;
   }
   
   public void setFunctions(List<Function> fuctions) {
      this.functions = fuctions;
   }
   
   public String getIcon() {
      return icon;
   }
   
   public void setIcon(String icon) {
      this.icon = icon;
   }
   
   public String getLabel() {
      return label;
   }
   
   public void setLabel(String label) {
      this.label = label;
   }
   
   public OrganisationUnit getParentUnit() {
      return parentUnit;
   }
   
   public void setParentUnit(OrganisationUnit parentUnit) {
      this.parentUnit = parentUnit;
   }
   
   public long getId() {
      return id;
   }

   public boolean isExpanded() {
      return expanded;
   }

   public void setExpanded(boolean expanded) {
      this.expanded = expanded;
   }

   public boolean isVisible() {
      return visible;
   }

   public void setVisible(boolean visible) {
      this.visible = visible;
   }
   
   
}

Selection HQL is: FROM OrganisationUnit WHERE parentUnit IS NULL.

In the database there only exists one single entry with parentUnit IS NULL.

After doing the corresponding remote call to an ssb I get one single entity instance of OrganisationUnit. BUT when I loop over the list of chield Units:

Code:

 for (OrganistionUnit subOU: ouHome.getChildUnits()) {
   ...
 }

Some of the list elements are null! But they cant be null, I checked this over and over again. I am getting the right number of elements.
Interesting is, that the null-elements are elements, which do not have chieldUnits them self. If a subOU has one or more chield units, all its attributes are filled correctly. The problems seems to be recursive.

I could not solve this issue, so I tried JBoss 4.2.0CR1 with Hibernate 3.2.1 but got the same problem.

Does anyone had erros like my one?

Thank you.

Meikel

evdelst · **Joined:** Wed Aug 24, 2005 11:49 am **Posts:** 63

I think it is because you use 'id' as indexcolumn.
Hibernate normally updates the indexcolumn to maintain the collection order.

When loading the collection, you will get a list with the elements on the position of the value of 'id', and null on all other positions in the list (since a list can contain null values, this is what Hibernate SHOULD do).