[OJB-developers] Mapping Single Table Inheritance

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

I'm trying to map two classes to a single table, but I can't seem to get the
mapping file correct. I have a basic inheritance test where B inherits from A.
When I run the test case, the A classes read in fine, but I get a
java.util.NoSuchElementException when I start reading in the B's. I'm using
0.7.325. What am I doing wrong?

Here's what I have:

A.java
------
package plprototype2.domain;

public class A {
     protected String ojbConcreteClass;

     public int id;
     public String aString;

     public A() {
          ojbConcreteClass = A.class.getName();
     }

     public A(int id, String objConcreteClass, String aString) {
          this.id = id;
          ojbConcreteClass = A.class.getName();
          this.aString = aString;
     }

     public String getConcreteClass() {
          return ojbConcreteClass;
     }
}

B.java
------
package plprototype2.domain;

public class B extends A {
     public String bString;

     public B() {
          ojbConcreteClass = B.class.getName();
     }

     public B(int id, String objConcreteClass, String aString, String bString) {
          super(id, objConcreteClass, aString);
          ojbConcreteClass = B.class.getName();
          this.bString = bString;
     }
}

SingleTableInheritanceTest.java
-------------------------------
package plprototype2.tests;

import junit.framework.Assert;
import junit.framework.TestCase;
import ojb.broker.PersistenceBroker;
import ojb.broker.PersistenceBrokerException;
import ojb.broker.PersistenceBrokerFactory;
import ojb.broker.TransactionNotInProgressException;
import ojb.broker.query.Criteria;
import ojb.broker.query.Query;
import ojb.broker.query.QueryByCriteria;
import ojb.broker.util.Logger;
import ojb.broker.util.LoggerFactory;
import plprototype2.domain.A;

import java.util.Iterator;

public class SingleTableInheritanceTest extends TestCase {

     /**
     * 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 = SingleTableInheritanceTest.class;

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

     protected PersistenceBroker broker;
     protected Logger logger;

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

     /**
     * Sets up the fixture, for example, open a network connection.
     * This method is called before a test is executed.
     */
     protected void setUp() throws Exception {
          broker = PersistenceBrokerFactory.createPersistenceBroker();
          logger = LoggerFactory.getLogger(this.getClass());
     }

     /**
     * Tears down the fixture, for example, close a network connection.
     * This method is called after a test is executed.
     */
     protected void tearDown() throws Exception {
          try {
               broker.clearCache();
          }
          catch (PersistenceBrokerException e) {
               logger.error("Exception during tearDown(): " + e.getMessage());
          }
     }

     public void testSingleTableInheritance() {
          try {
               logger.info("Querying all A objects...");

               // These should already be in the database (set up by
mapping.sql).
               Criteria selectAll = null;
               Query q = new QueryByCriteria(A.class, selectAll);

               Iterator iterator = broker.getIteratorByQuery(q);
               while (iterator.hasNext()) {
                    Object o = iterator.next();
                    A a = (A) o;
                    logger.info("Checking " + a.getConcreteClass() + " vs. " +
o.getClass().getName() + ".");
                    Assert.assertEquals(a.getConcreteClass(),
o.getClass().getName());
               }

               logger.info("Inheritance query succeeded!");
          }
          catch (Throwable t) {
               // As of ojb-0.7.325, isInTransaction() is not part of the
               // PersistenceBroker interface, so we have to check the hard way.
               try {
                    broker.abortTransaction();
               }
               catch (TransactionNotInProgressException e) {
               }
               logger.info("Inheritance query failed!");
               t.printStackTrace();
               Assert.assertTrue(false);
          }

     }
}

mapping.xml
-----------

... <driver stuff deleted>  ...

<ClassDescriptor id="9">
<class.name>plprototype2.domain.B</class.name>
<table.name>AB_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>ojbConcreteClass</field.name>
<column.name>CLASS_NAME</column.name>
<jdbc_type>VARCHAR</jdbc_type>
</FieldDescriptor>
<FieldDescriptor id="3">
<field.name>aString</field.name>
<column.name>A_STRING</column.name>
<jdbc_type>VARCHAR</jdbc_type>
</FieldDescriptor>
<FieldDescriptor id="4">
<field.name>bString</field.name>
<column.name>B_STRING</column.name>
<jdbc_type>VARCHAR</jdbc_type>
</FieldDescriptor>
</ClassDescriptor>

<ClassDescriptor id="10">
<class.name>plprototype2.domain.A</class.name>
<class.extent>plprototype2.domain.B</class.extent>
<table.name>AB_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>ojbConcreteClass</field.name>
<column.name>CLASS_NAME</column.name>
<jdbc_type>VARCHAR</jdbc_type>
</FieldDescriptor>
<FieldDescriptor id="3">
<field.name>aString</field.name>
<column.name>A_STRING</column.name>
<jdbc_type>VARCHAR</jdbc_type>
</FieldDescriptor>
</ClassDescriptor>

...

schema.sql
----------

DROP TABLE AB_TABLE;
CREATE TABLE AB_TABLE
(    ID INT NOT NULL PRIMARY KEY,
     CLASS_NAME VARCHAR(128),
     A_STRING VARCHAR(60),
     B_STRING VARCHAR(60)
);

INSERT INTO AB_TABLE VALUES (1,'plprototype2.domain.A','A1',NULL);
INSERT INTO AB_TABLE VALUES (2,'plprototype2.domain.A','A2',NULL);
INSERT INTO AB_TABLE VALUES (3,'plprototype2.domain.A','A3',NULL);
INSERT INTO AB_TABLE VALUES (4,'plprototype2.domain.B','B4','B4');
INSERT INTO AB_TABLE VALUES (5,'plprototype2.domain.B','B5','B5');

output
------
.[BOOT] INFO: OJB.properties: file:/C:/Personal/plprototype2/src/OJB.properties
0 INFO [main] tests.SingleTableInheritanceTest - Querying all A objects...
671 WARN [main] DEFAULT - Please define a public constructor for class
plprototype2.domain.A
with the following signature: (int, java.lang.String, java.lang.String).
It must initialize the classes persistent attributes. This is recommended to
increase performance but it's not mandatory!
681 INFO [main] tests.SingleTableInheritanceTest - Checking
plprototype2.domain.A vs. plprototype2.domain.A.
681 INFO [main] tests.SingleTableInheritanceTest - Checking
plprototype2.domain.A vs. plprototype2.domain.A.
691 INFO [main] tests.SingleTableInheritanceTest - Checking
plprototype2.domain.A vs. plprototype2.domain.A.
691 WARN [main] DEFAULT - Please define a public constructor for class
plprototype2.domain.B
with the following signature: (int, java.lang.String, java.lang.String,
java.lang.String).
It must initialize the classes persistent attributes. This is recommended to
increase performance but it's not mandatory!
691 ERROR [main] accesslayer.RsIterator - 3
701 INFO [main] tests.SingleTableInheritanceTest - Inheritance query failed!
java.util.NoSuchElementException
at ojb.broker.accesslayer.RsIterator.next(RsIterator.java:151)
at
plprototype2.tests.SingleTableInheritanceTest.testSingleTableInheritance(SingleTableInheritanceTest.java:81)


at java.lang.reflect.Method.invoke(Native Method)
at junit.framework.TestCase.runTest(TestCase.java:166)
at junit.framework.TestCase.runBare(TestCase.java:140)
at junit.framework.TestResult$1.protect(TestResult.java:106)
at junit.framework.TestResult.runProtected(TestResult.java:124)
at junit.framework.TestResult.run(TestResult.java:109)
at junit.framework.TestCase.run(TestCase.java:131)
at junit.framework.TestSuite.runTest(TestSuite.java:173)
at junit.framework.TestSuite.run(TestSuite.java:168)
at junit.textui.TestRunner.doRun(TestRunner.java:74)
at junit.textui.TestRunner.start(TestRunner.java:234)
at junit.textui.TestRunner.main(TestRunner.java:112)
at
plprototype2.tests.SingleTableInheritanceTest.main(SingleTableInheritanceTest.java:39)


F
Time: 1.953
There was 1 failure:
1)
testSingleTableInheritance(plprototype2.tests.SingleTableInheritanceTest)junit.framework.AssertionFailedError


at
plprototype2.tests.SingleTableInheritanceTest.testSingleTableInheritance(SingleTableInheritanceTest.java:99)


at
plprototype2.tests.SingleTableInheritanceTest.main(SingleTableInheritanceTest.java:39)



FAILURES!!!
Tests run: 1, Failures: 1, Errors: 0