Class Cast Exception with OneToMany association

peiguo · **Joined:** Mon Jun 16, 2008 1:15 pm **Posts:** 15

Hibernate version: the version comes with JBoss 4.2.2

I have two entities defined. First one like this:

Second entity:

My query is:

Name and version of the database you are using:
Oracle 10g
Full stack trace of any exception that occurs:

hlfsousa · **Posted:** Tue Jul 29, 2008 8:22 am

One problem is here:

Code:

   @OneToMany(cascade = CascadeType.ALL, mappedBy = "item")
   @JoinColumn(name = "bitm_numb", referencedColumnName = "bitm_numb_chld")
   private List<Sos> sos;

First of all, you should not have mappedBy and @JoinColumn in the same relationship. Second and most importantly, property "item" in Sos is int, but Hibernate expects, as in any inverse relationship, that property "item" is of type DpacRelt.

Here is how your entities should look like:

Code:

@Entity
@Table(name = "dpac_relt", schema = "dcs3000")
public class DpacRelt
{
   @Id
   @Column(name = "bitm_numb_parn")
   private int parent;

   @Column(name = "bitm_numb_chld")
   private int child;

   @OneToMany(cascade = CascadeType.ALL, mappedBy = "item")
   private List<Sos> sos;

   public int getParent()
   {
      return parent;
   }

   public void setParent(int parent)
   {
      this.parent = parent;
   }

   public int getChild()
   {
      return child;
   }

   public void setChild(int child)
   {
      this.child = child;
   }

   public List<Sos> getSos()
   {
      return sos;
   }

   public void setSos(List<Sos> sos)
   {
      this.sos = sos;
   }
}

Code:

@Entity
@Table(name = "sos", schema = "dcs3000")
public class Sos
{
   @Id
   @Column(name = "sos_numb")
   private int sos;

   @ManyToOne
   @JoinColumn(name = "sos_item")
   private DpacRelt item;

   public int getSos()
   {
      return sos;
   }

   public void setSos(int sos)
   {
      this.sos = sos;
   }

   public DpacRelt getItem()
   {
      return item;
   }

   public void setItem(DpacRelt item)
   {
      this.item = item;
   }
}

Finally, I would recommend you to make your mapping closer to the requirements. I say that because I would expect "parent" and "child" to be some relationship instead of just ints. Also, an entity named Sos with a property of the same name seems odd.

Regards,

Henrique

peiguo · **Joined:** Mon Jun 16, 2008 1:15 pm **Posts:** 15

Thanks for your reply. However what I want is unidirectional mapping, so the map on the other end is not required.

Your comment about mappedBy is certainly correct.

I think this is a Hibernate bug.

peiguo · **Joined:** Mon Jun 16, 2008 1:15 pm **Posts:** 15

"implements Serializable" appears to be a requirement of the spec. Although JPA does not enforce it, it chocks on it occasionally.