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

[Mahler T. <tho...@it...>]

Hi Dale,

> 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?
>

This scenario is supported. There are several testcases in the package
test.ojb.broker testing this behaviour.

I the latest release (0.7.343) there have been some fixes to inheritance
related stuff. Please check if you still have problems with this new
release.

HTH,

Thomas
 
> 
> 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());
>    }
> }
> 
> 
> 
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