JoinColumn: using Parent class field

prabhupravi · **Joined:** Thu Mar 17, 2011 5:31 am **Posts:** 7

Hi,
I have the following class structure...

Parent.java
=====================

Code:

@Entity
@Table(name="TABLE1")
@Inheritance(strategy = InheritanceType.JOINED)
abstract class Parent{

   @Column(name="ID")
   @Id
   private Integer Id;
   ...
   ...
   
   @Column(name="D_SOURCE_ID")
   private Integer dSourceId;
}

SubClass.java
======================

Code:

@Entity
@Table(name="TABLE2")
@PrimaryKeyJoinColumn(name = "ID")
class SubClass extends Parent{

   ...
   ...
             /**
             *A List of CompositeElement objects.
             *
             */
   @OneToMany(fetch = FetchType.EAGER)
   @JoinColumn( ??? )
   private List<CompositeElement> element;

}

CompositeElement.java
=====================

Code:

@Entity
@Table(name="SIGN")
class CompositeElement {
   ...
   ...
   @Column(name="C_D_SOURCE_ID");
   private Integer compDSourceId;
}

As you can see, Subclass entity is child of Parent class entity.
Inside SubClass; there is a List of 'CompositeElement' objects;
the condition is that 'CompositeElement' objects must be fetched from 'SIGN' table when (Parent.dSourceId == CompositeElement.compDSourceId).

What should i do in JoinColumn so that this can be done??!!!

Appreciate help

Regards,
Pravin

mmerder · **Posted:** Wed Mar 23, 2011 5:54 am

Is it possible to normalize you schema?

Is the column dSourceId unique? if yes, you could also join using the primary key. if not, you actually have a many-to-many relationship.

if the relationship is mapped through a property of the parent class, why don't you map the collection there?

prabhupravi · **Joined:** Thu Mar 17, 2011 5:31 am **Posts:** 7

mmerder wrote:

Is it possible to normalize you schema?

Is the column dSourceId unique? if yes, you could also join using the primary key. if not, you actually have a many-to-many relationship.

if the relationship is mapped through a property of the parent class, why don't you map the collection there?

Hi,

Normalization cannot be done, unfortunately :( . DB modification is not in my hands.

dSourceId is not unique.
There are other subclasses of the parent class, we do not want to make this list available to other subclasses.

Thanks and Regards,
Pravin