[OJB-developers] Base class queries on inheritance mapped to 2 tables

[<Dal...@bd...>]

Is it possible to query for all instances of a base class if its descendents are
mapped to another table using the PersistenceBroker API? I'm using inheritance
method #2 - two classes/two tables, each with all the fields from the base class
duplicated and the extents statement in the mapping definition for the base
class specifying its descendents. When I query for all instances of the base,
however, I never get any of the descendents. If this functionality is supposed
to work in OJB, what am I doing wrong?


Base.java
---------------
package plprototype2.domain;

public class Base {

   public int id;
   public String aString;

   public Base() {
   }

   public Base(int id, String aString) {
      this.id = id;
      this.aString = aString;
   }

}


Descendent.java
---------------
package plprototype2.domain;

public class Descendent extends Base {
   public String bString;

   public Descendent() {
   }

   public Descendent(int id, String aString, String bString) {
      super(id, aString);
      this.bString = bString;
   }
}


schema.sql
---------------
DROP TABLE BASE_TABLE;
CREATE TABLE BASE_TABLE
(  ID             INT NOT NULL PRIMARY KEY,
   A_STRING       VARCHAR(60)
);

DROP TABLE DESCENDENT_TABLE;
CREATE TABLE DESCENDENT_TABLE
(  ID             INT NOT NULL PRIMARY KEY,
   A_STRING       VARCHAR(60),
   B_STRING       VARCHAR(60)
);

INSERT INTO BASE_TABLE VALUES (1,'Base 1');
INSERT INTO BASE_TABLE VALUES (2,'Base 2');

INSERT INTO DESCENDENT_TABLE VALUES (1,'Descendent 1','1');
INSERT INTO DESCENDENT_TABLE VALUES (2,'Descendent 2','2');


repositor.xml
---------------
...<stuff clipped>...

   <ClassDescriptor id="26">
      <class.name>plprototype2.domain.Base</class.name>
      <class.extent>plprototype2.domain.Descendent</class.extent>
      <table.name>BASE_TABLE</table.name>
      <FieldDescriptor id="1">
         <field.name>id</field.name>
         <column.name>ID</column.name>
         <jdbc_type>INTEGER</jdbc_type>
         <PrimaryKey>true</PrimaryKey>
         <autoincrement>true</autoincrement>
      </FieldDescriptor>
      <FieldDescriptor id="2">
         <field.name>aString</field.name>
         <column.name>A_STRING</column.name>
         <jdbc_type>VARCHAR</jdbc_type>
      </FieldDescriptor>
   </ClassDescriptor>

   <ClassDescriptor id="25">
      <class.name>plprototype2.domain.Descendent</class.name>
      <table.name>DESCENDENT_TABLE</table.name>
      <FieldDescriptor id="1">
         <field.name>id</field.name>
         <column.name>ID</column.name>
         <jdbc_type>INTEGER</jdbc_type>
         <PrimaryKey>true</PrimaryKey>
         <autoincrement>true</autoincrement>
      </FieldDescriptor>
      <FieldDescriptor id="2">
         <field.name>aString</field.name>
         <column.name>A_STRING</column.name>
         <jdbc_type>VARCHAR</jdbc_type>
      </FieldDescriptor>
      <FieldDescriptor id="3">
         <field.name>bString</field.name>
         <column.name>B_STRING</column.name>
         <jdbc_type>VARCHAR</jdbc_type>
      </FieldDescriptor>
   </ClassDescriptor>

...<stuff clipped>...


PerClassTableInheritanceTest.java
---------------
package plprototype2.tests;

import ojb.broker.query.Criteria;
import ojb.broker.query.Query;
import ojb.broker.query.QueryByExample;
import ojb.broker.query.QueryByCriteria;
import plprototype2.domain.Base;

import java.util.Collection;

import junit.framework.Assert;

public class PerClassTableInheritanceTest extends OJBTestCase {

   /**
    * Static reference to .class. Java does not provide any way to obtain the
    * Class object from static method without naming it.
    */
   private static Class CLASS = PerClassTableInheritanceTest.class;

   /**
    * Runs the suite in a junit.textui.TestRunner.
    */
   public static void main(String[] args) {
      String[] arr = {CLASS.getName()};
      junit.textui.TestRunner.main(arr);
   }

   public PerClassTableInheritanceTest(String name) {
      super(name);
   }

   /**
    * Query all objects of Type "Base". You should get 2 from BASE_TABLE and
    * 2 from DESCENDENT_TABLE.
    */
   public void testInheritance() {
      Criteria selectAll = null;
      Query q = new QueryByCriteria(Base.class, selectAll);
      Collection c = broker.getCollectionByQuery(q);
      logger.info("Base class query returned "+c.size()+" objects.");
      Assert.assertEquals("Incorrect number of Base objects returned!", 4,
c.size());
   }
}