RE: Persisting Inheritance..

[Lemke, Wesley]

Looks like the list doesn't allow attachments, if anyone wants to see
the diagram, it is here:
http://leadgroupinc.com/gallery/DrunkOMatic/diagram.jpg

-----Original Message-----
From: Lemke, Wesley [mailto:[EMAIL PROTECTED] 
Sent: Monday, February 14, 2005 4:12 PM
To: ojb-dev@db.apache.org
Subject: Persisting Inheritance..


I have already posted this to the user list, but was unable to resolve
this issue.  I then started looking into the OJB code, and have narrowed
the problem down, but still need some help.  Here is the situation:

I have 3 classes defined as follows:

public class Shape {
        Long id;
        String shapeInfo = "shape";
        List sides = new ArrayList();
        ...
}       
public class Square extends Shape {
        Long id;
        String squareInfo = "square";
        ...
}       
public class Side {
        Long id;
        Shape shape;
        ...
}

A simple class diagram is attached.  
Here is the repository.xml file:

   <jdbc-connection-descriptor
        jcd-alias="default"
        default-connection="true"
        platform="Db2"
        jdbc-level="1.0"
        jndi-datasource-name="jdbc/AffinityDS"
        batch-mode="false"
    >
        <sequence-manager
className="org.apache.ojb.broker.util.sequence.SequenceManagerNativeImpl
">
           <attribute attribute-name="autoNaming"
attribute-value="true"/>
        </sequence-manager>
    </jdbc-connection-descriptor>

<class-descriptor
          class="model.Shape"
          table="shape"
   >
      <field-descriptor
         name="id"
         column="shape_id"
         jdbc-type="BIGINT"
         primarykey="true"
         autoincrement="true"
      />    
      <field-descriptor
        name="shapeInfo"
        column="shape_info"
                jdbc-type="VARCHAR"
      />
     <collection-descriptor
        name="sides"
        element-class-ref="model.Side"
        auto-delete="true"
        auto-update="true"
      >
                <inverse-foreignkey field-ref="side" />
      </collection-descriptor>
    </class-descriptor>

<class-descriptor
        class="model.Square"
        table="square"
        >
        <field-descriptor
                name="id"
                column="square_id"
                jdbc-type="BIGINT"
                primarykey="true"
                autoincrement="true"
        />
        <field-descriptor
                name="squareInfo"
                column="square_info"
                jdbc-type="VARCHAR"
        />
        <reference-descriptor name="super"
        class-ref="model.Shape"
        auto-retrieve="true"
        auto-update="true"
        auto-delete="true"
    >
        <foreignkey field-ref="id"/>
    </reference-descriptor>
</class-descriptor>

<class-descriptor
        class="model.Side"
        table="side"
        >
        <field-descriptor
                name="id"
                column="side_id"
                jdbc-type="BIGINT"
                primarykey="true"
                autoincrement="true"
        />
      <field-descriptor
         name="shape"
         column="shape_id"
         jdbc-type="BIGINT"
         access="anonymous"
      />
      <reference-descriptor name="shape" class-ref="model.Shape">
        <foreignkey field-ref="shape"/>
      </reference-descriptor>
</class-descriptor>

Here is the code I am using:

broker.beginTransaction();
Square square = new Square();
for (int i = 0; i < 4; i++) {
        Side side = new Side();
        square.addSide(side);
        side.setShape(square);
}
broker.store(square);
broker.commitTransaction();

Here is what the database looks like after I run this code:

Shape:
shape_id        shape_info
-3              shape


Square:
square_id       square_info
-3              square


Side:
side_id shape_id
-4              -2
-5              -2
-6              -2
-7              -2
-8              -2


As you can see the foreign key in the Side table is incorrect (or the
foreign keys in the shape/square tables are incorrect).  When you try to
retrieve the Square object, the join will fail.  I have tracked this
down to this area of the code (OJB 1.0.1,
org.apache.ojb.broker.core.PersistenceBrokerImpl.java,  line 1033 or
so):

for (int i = 0; i < objFkFields.length; i++)
{
    fld = objFkFields[i];
    /*
    arminw:
    we set the FK value when the extracted PK fields from the referenced
object are not null at all
    or if null, the FK field was not a PK field of target object too.
    Should be ok, because the values of the extracted PK field values
should never be null and never
    change, so it doesn't matter if the target field is a PK too.
    */
    if(refPkValues != null || !fld.isPrimaryKey())
    {
        //Comment by me:  This is where the key gets changed.  It also
looks like the keys
        //to the Side objects get changed, but they don't get persisted
to the database correctly....
        fld.getPersistentField().set(targetObject, refPkValues != null ?
refPkValues[i].getValue(): null);
    }
}

See my comment above in the code (I believe they are correct).


Can anyone offer any assistance or guidance on what the problem could
be?  I've been working on this issue (in different ways) for a few weeks
now.  If any more information is needed, let me know.

Thanks in advance,
Wes

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