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andy_p
 Post subject: ClassCastException after joined-subclass load
PostPosted: Mon Oct 03, 2005 1:19 am 
Newbie

Joined: Sun Oct 02, 2005 11:39 pm
Posts: 3
JDK 1.5.0_04

Hibernate version: 3.0.5

Mapping documents:

Code:
<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping>
  <class name="au.gov.vic.ngv.shop.admin.model.Person">
    <id name="ID">
      <generator class="increment"/>
    </id>
    <property name="name"/>
    <joined-subclass name="au.gov.vic.ngv.shop.admin.model.Manager" lazy="false">
      <key column="ID"/>
      <property name="bonus"/>
    </joined-subclass>
  </class>
</hibernate-mapping>


Code between sessionFactory.openSession() and session.close():

Code:
      
Manager manager = (Manager) sess.load(Person.class,new Long(1));


Full stack trace of any exception that occurs:

java.lang.ClassCastException: au.gov.vic.ngv.shop.admin.model.Person$$EnhancerByCGLIB$$36a08cbc
at au.gov.vic.ngv.shop.admin.dao.TestProductDAO.testLoadPerson(TestProductDAO.java:29)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at junit.framework.TestCase.runTest(TestCase.java:154)
at junit.framework.TestCase.runBare(TestCase.java:127)
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:118)
at junit.framework.TestSuite.runTest(TestSuite.java:208)
at junit.framework.TestSuite.run(TestSuite.java:203)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:478)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:344)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:196)


Name and version of the database you are using: SQL Server 2000


I can't understand why this is not working and I've searched everywhere. Can anyone see if I may have missed anything?

If I use Manager.class in the load() method instead of the superclass:

Code:
Manager manager = (Manager) sess.load(Manager.class,new Long(1));


it works fine, but this means I can't load objects polymorphically.
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d
 Post subject:
PostPosted: Mon Oct 03, 2005 1:50 am 
Expert
Expert

Joined: Mon Jul 04, 2005 5:19 pm
Posts: 720
think about this. every dog is a mammal, but not every mammal is a dog.
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andy_p
 Post subject:
PostPosted: Mon Oct 03, 2005 2:10 am 
Newbie

Joined: Sun Oct 02, 2005 11:39 pm
Posts: 3
dennisbyrne wrote:
think about this. every dog is a mammal, but not every mammal is a dog.


Hi Dennis,

I should still be able to load a Person object without knowing its runtime class and then cast it later. The following example comes straight from the hibernate manual:

Code:
DomesticCat pk = (DomesticCat) sess.load( Cat.class, new Long(pkId) );


I'm pretty sure that this does the same thing that I am attempting.

Thanks anyway.
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gavin
 Post subject:
PostPosted: Mon Oct 03, 2005 2:39 am 
Hibernate Team
Hibernate Team

Joined: Tue Aug 26, 2003 12:50 pm
Posts: 5130
Location: Melbourne, Australia
You must use session.get(), or simply never write such evil non-object oriented stuff. Real OO code uses polymorphism, not typecasts.
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andy_p
 Post subject:
PostPosted: Mon Oct 03, 2005 3:02 am 
Newbie

Joined: Sun Oct 02, 2005 11:39 pm
Posts: 3
gavin wrote:
You must use session.get(), or simply never write such evil non-object oriented stuff. Real OO code uses polymorphism, not typecasts.


Hey, just copying the examples in the manual.
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gavin
 Post subject:
PostPosted: Mon Oct 03, 2005 3:49 am 
Hibernate Team
Hibernate Team

Joined: Tue Aug 26, 2003 12:50 pm
Posts: 5130
Location: Melbourne, Australia
Yes, the example is wrong.
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