Entity bean association ???

[jc7442]

Hi,

I have the folowing entity bean:

@Entity()
public class NodeBO implements Persistent {
 ...
 private NodeBO parent;
 @ManyToOne
 public NodeBO getParent() {
 return parent;
 }

 public void setParent(NodeBO parent) {
 this.parent = parent;
 }
}

First I do not write ManyToOne annotations. I create 2 instances :n1 and :n2, :n1 has no parent and :n2 has :n1 has parent. I retrieve :n2 by a query, if I invoke getParent method on :n2, it returns :n2.

I just add the annotaions and with the same code now it works fine.

I do not understand the differences between my 2 codes. Any explanations are welcome.

When there is no annotations, having a look to DB, parent field is mapped using a tiny blob. It should correspond to a default annotation what's the default annotation ?

Explanations or reference in the documentation on how to manage bean association are welcome !!!

J-C

[epbernard]

I don't know what you're talking about.
An association has to have an annotation describing it's logical multiplicity

[jc7442]

If I do not specify any association, entity bean are deployed, I can create instance in the DB and when I look the DB using an SQL browser (I have a mySql db), I can see a column with the name of my field containing a tiny blob.
If I add the ManyToOne annotation, using the same browser I see that the mapping for my object has changed and now instead of a tiny blob, I see the PK of the objects.
My question was just to understand why with no annotation I have a tiny blob (is it a default value or something that may be paramater ?).

Another problem I try to solve is:
- I have a node entity bean that handles an interface leaf. In JDO2, this kind of mapping is possible, I just need to specify the list of valid classes that implment this interface (if classes are not specified, all classes are valid). I try to do the same with hibernate, I do not find annotation to specify the list of valid classes. If I just add ManyToOne annotation, I have the following exception at deployment time:

16:48:41,536 WARN [ServiceController] Problem creating service jboss.j2ee:module=Persistence.par,uid=20796783,service=EJB3
org.hibernate.AnnotationException: Unable to find entity fr.biomerieux.dnachip.bo.classification.Leaf
 at org.hibernate.cfg.AnnotationBinder.bindFkSecondPass(AnnotationBinder.java:1480)
 at org.hibernate.cfg.FkSecondPass.secondPass(FkSecondPass.java:37)
 at org.hibernate.cfg.FkSecondPass.doSecondPass(FkSecondPass.java:31)
 at org.hibernate.cfg.AnnotationConfiguration.secondPassCompile(AnnotationConfiguration.java:215)
 at org.hibernate.cfg.Configuration.buildMappings(Configuration.java:876)
 at org.hibernate.ejb.HibernatePersistence.handleListenerCallbacks(HibernatePersistence.java:448)
 at org.hibernate.ejb.HibernatePersistence.createEntityManagerFactory(HibernatePersistence.java:438)
 at org.hibernate.ejb.HibernatePersistence.createContainerEntityManagerFactory(HibernatePersistence.java:272)
 at org.jboss.ejb3.Ejb3Deployment.initializeManagedEntityManagerFactory(Ejb3Deployment.java:476)
 at org.jboss.ejb3.Ejb3Deployment.create(Ejb3Deployment.java:219)
 at org.jboss.ejb3.Ejb3Module.createService(Ejb3Module.java:34)
 at org.jboss.system.ServiceMBeanSupport.jbossInternalCreate(ServiceMBeanSupport.java:252)
 at org.jboss.system.ServiceMBeanSupport.jbossInternalLifecycle(ServiceMBeanSupport.java:234)
 at sun.reflect.GeneratedMethodAccessor2.invoke(Unknown Source)
 at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
 at java.lang.reflect.Method.invoke(Method.java:585)
 at org.jboss.mx.interceptor.ReflectedDispatcher.invoke(ReflectedDispatcher.java:141)
 at org.jboss.mx.server.Invocation.dispatch(Invocation.java:80)
 at org.jboss.mx.server.Invocation.invoke(Invocation.java:72)
 at org.jboss.mx.server.AbstractMBeanInvoker.invoke(AbstractMBeanInvoker.java:245)
 at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:644)
 at org.jboss.system.ServiceController$ServiceProxy.invoke(ServiceController.java:974)
 at $Proxy0.create(Unknown Source)
 at org.jboss.system.ServiceController.create(ServiceController.java:356)
 at org.jboss.system.ServiceController.create(ServiceController.java:295)
 at sun.reflect.GeneratedMethodAccessor4.invoke(Unknown Source)
 at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
 at java.lang.reflect.Method.invoke(Method.java:585)
 at org.jboss.mx.interceptor.ReflectedDispatcher.invoke(ReflectedDispatcher.java:141)
 at org.jboss.mx.server.Invocation.dispatch(Invocation.java:80)
 at org.jboss.mx.server.Invocation.invoke(Invocation.java:72)
 at org.jboss.mx.server.AbstractMBeanInvoker.invoke(AbstractMBeanInvoker.java:245)
 at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:644)
 at org.jboss.mx.util.MBeanProxyExt.invoke(MBeanProxyExt.java:176)
 at $Proxy17.create(Unknown Source)
 at org.jboss.ejb3.EJB3Deployer.create(EJB3Deployer.java:178)
 at org.jboss.deployment.MainDeployer.create(MainDeployer.java:919)
 at org.jboss.deployment.MainDeployer.create(MainDeployer.java:909)
 at org.jboss.deployment.MainDeployer.deploy(MainDeployer.java:773)
 at org.jboss.deployment.MainDeployer.deploy(MainDeployer.java:737)
 at sun.reflect.GeneratedMethodAccessor16.invoke(Unknown Source)
 at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
 at java.lang.reflect.Method.invoke(Method.java:585)
 at org.jboss.mx.interceptor.ReflectedDispatcher.invoke(ReflectedDispatcher.java:141)
 at org.jboss.mx.server.Invocation.dispatch(Invocation.java:80)
 at org.jboss.mx.interceptor.AbstractInterceptor.invoke(AbstractInterceptor.java:118)
 at org.jboss.mx.server.Invocation.invoke(Invocation.java:74)
 at org.jboss.mx.interceptor.ModelMBeanOperationInterceptor.invoke(ModelMBeanOperationInterceptor.java:127)
 at org.jboss.mx.server.Invocation.invoke(Invocation.java:74)
 at org.jboss.mx.server.AbstractMBeanInvoker.invoke(AbstractMBeanInvoker.java:245)
 at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:644)
 at org.jboss.mx.util.MBeanProxyExt.invoke(MBeanProxyExt.java:176)
 at $Proxy9.deploy(Unknown Source)

I probably just missed something in the mapping, but I can not find what !!!

[jc7442]

A thread that answer my interface problem:
http://forum.hibernate.org/viewtopic.php?p=2238824#2238824