[Hibernate-issues] [Hibernate-JIRA] Created: (HB-406) graph loading breaks on complex hierarchies

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  A new issue has been created in JIRA.

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View the issue:

  http://opensource.atlassian.com/projects/hibernate/secure/ViewIssue.jspa?key=HB-406


Here is an overview of the issue:
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        Key: HB-406
    Summary: graph loading breaks on complex hierarchies
       Type: Bug

     Status: Unassigned
   Priority: Major

    Project: Hibernate2
 Components: 
             core
   Versions:
             2.0.3

   Assignee: 
   Reporter: Andrey Volozin

    Created: Thu, 16 Oct 2003 9:57 AM
    Updated: Thu, 16 Oct 2003 9:57 AM
Environment: Pentium IV 2.40 GHz, Windows XP, JDK 1.3

Description:
I have a relatively complex hierarchy of objects:

A is common superclass
B, C, D are subclasses
D incapsulates collections of B and C

here is my hbm.xml file:

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
   "-//Hibernate/Hibernate Mapping DTD//EN"
   "http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">

<hibernate-mapping>
    <class name="A">
    
    <id name="id">
       <generator class="hilo">
          <param name="table">hi_value</param>
          <param name="column">next_value</param>
          <param name="max_lo">100</param>
        </generator>
    </id>
    
    <discriminator column="class_name"/>     
    
    <property name="f1"/>    
    
    <subclass name="B">
       <property name="f2"/>
    </subclass>
        
    <subclass name="C">
       <property name="f3"/>              
    </subclass>
            
    <subclass name="D">
      <set name="lnkB" cascade="all">
          <key column="d_id"/>
          <one-to-many class="B"/>       
      </set>       
      
      <set name="lnkC" cascade="all">
          <key column="d_id"/>
          <one-to-many class="C"/>       
      </set>       
       
      <property name="f4"/>
    </subclass>
               
    </class>

</hibernate-mapping>


here are the classes:

public abstract class A {
	
	private Long id;	
	private String f1;

	public Long getId() { return id; }
        public void setId(Long id) { this.id = id; }

	public String getF1() { return f1; }
        public void setF1(String f1) { this.f1 = f1; }
}

public class B extends A {
	
	private String f2;

	public String getF2() { return f2; }
        public void setF2(String f2) { this.f2 = f2; }
}

public class C extends A {
	
	private String f3;

	public String getF3() { return f3; }
        public void setF3(String f3) { this.f3 = f3; }
}

public class D extends A {
	
	private String f4;
        private Collection lnkB;
        private Collection lnkC;

	public String getF4() { return f4; }
        public void setF4(String f4) { this.f4 = f4; }

	public Collection getLnkB() { return lnkB; }
        public void setLnkB(String lnkB) { this.lnkB = lnkB; }

	public String getLnkC() { return lnkC; }
        public void setLnkC(String lnkC) { this.lnkC = lnkC; }
}


I persisted data to the database using the following code:

public class TestMain {
	static Session session;
	static SessionFactory sessionFactory;

	public static Collection createB() throws HibernateException, SQLException {
		Collection results = new HashSet();		
		
		B b = new B();			
		b.setF2("foo");
		results.add(b);

		b = new B();			
		b.setF2("bar");
		results.add(b);								
		return results;
	}	

	public static Collection createC() throws HibernateException, SQLException {
		Collection results = new HashSet();		
		
		C c = new C();			
		c.setF3("foo");
		results.add(c);

		c = new C();			
		c.setF3("bar");
		results.add(c);
			
		return results;
	}	
		
	public static D createD(Collection b, Collection c) throws HibernateException, SQLException {
		D d = new D();
			
		d.setF1("foo");
		d.setLnkB(b);
                d.setLnkC(c);
		
       	        session.save (d);
		System.out.println ("Persisting D");
		
		return d;
	}			

	public static void main(String[] args) {
		D d;
		
		try {			
			sessionFactory = new Configuration().configure().buildSessionFactory();
			
			if (sessionFactory == null) { System.out.println ("null session factory returned"); return; }
			System.out.println ("Got Session Factory");
						
			session = sessionFactory.openSession();
			
			Collection b = createB();
                        Collection c = createC();

			d = createD(b, c);			
			
			session.flush();
   	    	        session.connection().commit();
    		        System.out.println ("Committing");	  
							
			session.close();
		} catch (MappingException e){
			System.out.println (e);
		} catch (HibernateException e) {
			System.out.println(e);
		} 		
		catch (Throwable e) {
			System.out.println (e);
			e.printStackTrace();
		}
	}
}


then I started my application again but instead of persistence I did retrieval (I looked up id of D instance in the database):

D d = (D) session.load(D.class, new Long(1615));

But it failed with the message:

Object with id: 1618 was not of the specified subclass: C (loaded object was of wrong class)

Indeed, the object with id 1618 had "B" in the discriminator field and database record corresponded to B instance.


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