CGLIB proxy & lazy loading problems in version 3

jramosd · **Joined:** Mon Aug 08, 2005 6:41 am **Posts:** 4

Hello,

I have been a long time trying to solve a problem that appeared when upgarding from hibernate 2.1 to version 3. I have an object of type AgencyOperator, inheriting from User, which contains a collection of BranchOffice's which in turn contain User's, as can be seen in the mapping pasted below.

With hibernate 2.1 I could instantiate an AgencyOperator and obtain from it the BranchOffice it is registered with, and from this one, the Agency it belongs to, like:

AgencyOperator.getBranchOffice().getAgency().

With hibernate 3 I experience problems with lazy loading. The BranchOffice property of AgencyOperator is a CGLIB proxy, that after examination with the debugger reveals to contain the correct object in its 'target' property.

However, when I investigate the content of the Agency property inside this BranchOffice object, I see a CGLIB proxy that contains a null reference in the 'target' property. The call to

AgencyOperator.getBranchOffice().getAgency(), then, gives me a null reference.

This is always before closing the HibernateSession.

After browsing documentation and googling, I cannot find the problem. Can anyone provide some help?

Thanks a lot in advance.

Hibernate version: 3.0.5
Name and version of the database you are using: Mysql 4.1
Mapping documents:

<class name="es.parsec.parsys.user.ParsysUser">
<id name="code" type="long" column="code" unsaved-value="null">
<generator class="native" />
</id>
<property name="name" type="string" />
<property name="password" type="string" />

<joined-subclass name="es.parsec.parsys.user.AgencyOperator" table="AgencyOperator">
<key column="code"/>
<many-to-one name="branchOffice" class="es.parsec.parsys.agency.BranchOffice" column="branchOffice"/>
</joined-subclass>
</class>

<class name="es.parsec.parsys.agency.BranchOffice">
<id name="code" type="long" column="code" unsaved-value="null">
<generator class="native"/>
</id>
<property name="name" type="string" length="40"/>
<many-to-one name="agency" column="agency" class="es.parsec.parsys.agency.Agency"/>
<set name="branchOperators" inverse="true" lazy="true" order-by="code" cascade="all">
<key column="branchOffice"/>
<one-to-many class="es.parsec.parsys.user.AgencyOperator"/>
</set>
</class>

<class name="es.parsec.parsys.agency.Agency">
<id name="code" type="long" column="code" unsaved-value="null">
<generator class="native"/>
</id>
<property name="name" type="string"/>
<set name="branchOffices" inverse="true" lazy="true" order-by="code" cascade="all">
<key column="agency"/>
<one-to-many class="es.parsec.parsys.agency.BranchOffice"/>
</set>
</class>

pksiv · **Posted:** Mon Aug 08, 2005 9:11 am

A couple of things...

You should never receive a lazy loading exception if the original session is still open and your object hasn't been evicted.

I sometimes experience strange behavior with Eclipse debugger where it appears the object is empty through the proxy but when I displayed the value through logging statements, it appeared correctly.

Can you show an example of your code ?

jramosd · **Joined:** Mon Aug 08, 2005 6:41 am **Posts:** 4

pksiv wrote:

A couple of things...

You should never receive a lazy loading exception if the original session is still open and your object hasn't been evicted.

I sometimes experience strange behavior with Eclipse debugger where it appears the object is empty through the proxy but when I displayed the value through logging statements, it appeared correctly.

Can you show an example of your code ?

Hi Preston,

I do not receive a lazy loading exception, I just get a null pointer reference wheng doing

Code:

AgencyOperator.getBranchOffice().getAgency()

Then I get NullPointerException when trying to read some property of the Agency.

Here is the code of my classes:

Code:

public class Agency 
{   

 private Long code;
 private String name;   
 private Set branchOffices = new LinkedHashSet();
   
 Agency()
 {
    
 }

 private Set getBranchOffices()
 {
  return branchOffices;
 }

 private void setBranchOffices(Set branchOffices)
 {
  this.branchOffices = branchOffices;
 }

 public Long getCode()
 {
  return code;
 }

 private void setCode(Long code)
 {
  this.code = code;
 }

 public String getName()
 {
  return name;
 }

 public void setName(String name)
 {
  this.name = name;
 }
   
}


public class BranchOffice 
{

 private Long code;
 private String name;
 private Set branchOperators = new LinkedHashSet();
   
 BranchOffice()
 {
    
 }
   
 public Agency getAgency()
 {
  return agency;
 }

 public void setAgency(Agency agency)
 {
  this.agency = agency;
 }

 public Long getCode()
 {
  return code;
 }

 private void setCode(Long code)
 {
  this.code = code;
 }
 
 public String getName()
 {
  return name;
 }
 
 public void setName(String name)
 {
  this.name = name;
 }

 private Set getBranchOperators()
 {
  return branchOperators;
 }

 private void setBranchOperators(Set branchOperators)
 {
  this.branchOperators = branchOperators;
 }

}

public abstract class ParsysUser implements Principal 
{
   
 private Long code;
 private String name;
 private String password;

 protected ParsysUser()
 {
  super();
 }

 public String getName()
 {
  return name;
 }

 public Long getCode()
 {
  return code;
 }

 private void setCode(Long code)
 {
  this.code = code;
 }

 public String getPassword()
 {
  return password;
 }

 public void setPassword(String password)
 {
  this.password = password;
 }

 public void setName(String name)
 {
 this.name = name;
 }
   
}

public class AgencyOperator extends ParsysUser 
{

 protected AgencyOperator()
 {
  super();
 }   
   
 private BranchOffice branchOffice;   
   
 public BranchOffice getBranchOffice()
 {
  return branchOffice;
 }

 public void setBranchOffice(BranchOffice branchOffice)
 {
  this.branchOffice = branchOffice;
 }

}

Thanks for your reply,

Javier

pksiv · **Posted:** Mon Aug 08, 2005 9:56 am

In your code example, the BranchOffice class has a getAgency() and setAgency() method but no actual agency property ? I don't see how this will compile.

jramosd · **Joined:** Mon Aug 08, 2005 6:41 am **Posts:** 4

pksiv wrote:

In your code example, the BranchOffice class has a getAgency() and setAgency() method but no actual agency property ? I don't see how this will compile.

Mmmmmh, sorry, the actual object is more complicated and I simplified it to send the example. I took away too much code.

pksiv · **Posted:** Mon Aug 08, 2005 10:26 am

jramosd wrote:

Mmmmmh, sorry, the actual object is more complicated and I simplified it to send the example. I took away too much code.

Not sure what to tell you.
I copied your mapping files and your Java class files(adding the agency property) into a test project and after inserting some data with the following code

Code:

      Session session = getSession();
      Transaction tx = session.beginTransaction();

      Agency agency1 = new Agency();
      agency1.setName("Test Agency 1");
      session.save(agency1);
            
      BranchOffice branchOffice1 = new BranchOffice();
      branchOffice1.setName("Branch Office 1");
      branchOffice1.setAgency(agency1);
      session.save(branchOffice1);
      BranchOffice branchOffice2 = new BranchOffice();
      branchOffice2.setName("Branch Office 2");
      branchOffice1.setAgency(agency1);
      session.save(branchOffice2);
      
      AgencyOperator agOp1 = new AgencyOperator();
      agOp1.setBranchOffice(branchOffice1);
      agOp1.setName("Preston");
      agOp1.setPassword("password");
      session.save(agOp1);
      try {
         tx.commit();
      } catch (HibernateException e) {
         e.printStackTrace();
      } finally {
           session.close();
      }
   

I executed a simple query and it seems to work as expected.

Code:

      Session session = getSession();
      try {
         Query q = session.createQuery("from AgencyOperator");
         for (Iterator i = q.list().iterator(); i.hasNext();) {
            AgencyOperator agOp = (AgencyOperator) i.next();
            System.out.print(agOp.getName() + " " + agOp.getBranchOffice().getName());   
            if (agOp.getBranchOffice().getAgency() == null) {
               System.out.println("Why am I null ?");
            } else {
               System.out.println(agOp.getBranchOffice().getAgency().getName());
            }
         }
      } catch (Throwable t) {
         t.printStackTrace();
      } finally {
         session.close();
      }

jramosd · **Joined:** Mon Aug 08, 2005 6:41 am **Posts:** 4

Thanks for testing, Preston.
I will do the same simple test here to see what I get.
Regards,

Javier

pksiv wrote:

jramosd wrote:

Mmmmmh, sorry, the actual object is more complicated and I simplified it to send the example. I took away too much code.

Not sure what to tell you.
I copied your mapping files and your Java class files(adding the agency property) into a test project and after inserting some data with the following code... [quote]