Simple Hibernate Application not working: PropertyAccessException: could not get a field value by reflection getter of

Question

I'm struggling with a simple hibernate application. (JBoss AS 7.1.1, Hibernate 4.1)

My entity bean:

@Entity
public class User implements Serializable {

    @Id
    private Long userId;

    public Long getUserId() {
    return userId;
    }

    public void setUserId(Long userId) {
        this.userId = userId;
    }
}

My persistence.xml:

<persistence xmlns="http://java.sun.com/xml/ns/persistence"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd"
version="2.0">
<persistence-unit name="users" transaction-type="JTA">
    <provider>org.hibernate.ejb.HibernatePersistence</provider>
    <jta-data-source>java:jboss/datasources/myDS</jta-data-source>
    <jar-file>users.jar</jar-file>
    <class>de.test.users.entities.User</class>
    <properties>
        <property name="hibernate.hbm2ddl.auto" value="update" />
        <property name="hibernate.archive.autodetection" value="class" />
        <property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect" />
        <property name="hibernate.show_sql" value="true" />
    </properties>
</persistence-unit>

My simple DAO bean:

@Stateless
public class UserManagerBean implements UserManager {

    @PersistenceContext(name = "users")
    private EntityManager em;

    public UserManagerBean() {
        // TODO Auto-generated constructor stub
    }

    @Override
    public void createUser() {
        User user = new User();
            user.setUserId(42L);
    em.persist(user);
    em.flush();
    }
}

I'm invoking the createUser method by an EJB injection of UserManagerBean in a JSF backing bean. When the persist method is called, i get the following:

javax.faces.el.EvaluationException: javax.ejb.EJBException: javax.persistence.PersistenceException: org.hibernate.PropertyAccessException: could not get a field value by reflection getter of de.test.users.entities.User.userId
at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:102)
at com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:102)
at javax.faces.component.UICommand.broadcast(UICommand.java:315)
at javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:794)
at javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:1259)
at com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:81)
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:118)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:593)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:329)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:248)
at org.jboss.weld.servlet.ConversationPropagationFilter.doFilter(ConversationPropagationFilter.java:62)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:280)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:248)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:275)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:161)
at org.jboss.as.jpa.interceptor.WebNonTxEmCloserValve.invoke(WebNonTxEmCloserValve.java:50)
at org.jboss.as.web.security.SecurityContextAssociationValve.invoke(SecurityContextAssociationValve.java:153)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:155)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:368)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:877)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:671)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:930)
at java.lang.Thread.run(Thread.java:722)
Caused by: javax.ejb.EJBException: javax.persistence.PersistenceException: org.hibernate.PropertyAccessException: could not get a field value by reflection getter of de.test.users.entities.User.userId
at org.jboss.as.ejb3.tx.CMTTxInterceptor.handleExceptionInOurTx(CMTTxInterceptor.java:166)
at org.jboss.as.ejb3.tx.CMTTxInterceptor.invokeInOurTx(CMTTxInterceptor.java:230)
at org.jboss.as.ejb3.tx.CMTTxInterceptor.required(CMTTxInterceptor.java:304)
at org.jboss.as.ejb3.tx.CMTTxInterceptor.processInvocation(CMTTxInterceptor.java:190)
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:288)
at org.jboss.as.ejb3.component.interceptors.CurrentInvocationContextInterceptor.processInvocation(CurrentInvocationContextInterceptor.java:41)
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:288)
at org.jboss.as.ejb3.component.interceptors.LoggingInterceptor.processInvocation(LoggingInterceptor.java:59)
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:288)
at org.jboss.as.ee.component.NamespaceContextInterceptor.processInvocation(NamespaceContextInterceptor.java:50)
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:288)
at org.jboss.as.ejb3.component.interceptors.AdditionalSetupInterceptor.processInvocation(AdditionalSetupInterceptor.java:32)
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:288)
at org.jboss.as.ee.component.TCCLInterceptor.processInvocation(TCCLInterceptor.java:45)
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:288)
at org.jboss.invocation.ChainedInterceptor.processInvocation(ChainedInterceptor.java:61)
at org.jboss.as.ee.component.ViewService$View.invoke(ViewService.java:165)
at org.jboss.as.ee.component.ViewDescription$1.processInvocation(ViewDescription.java:173)
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:288)
at org.jboss.invocation.ChainedInterceptor.processInvocation(ChainedInterceptor.java:61)
at org.jboss.as.ee.component.ProxyInvocationHandler.invoke(ProxyInvocationHandler.java:72)
at de.test.users.service.UserManager$$$view1.createUser(Unknown Source)
at de.test.users.User.createUser(User.java:17)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:601)
at org.apache.el.parser.AstValue.invoke(AstValue.java:262)
at org.apache.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:278)
at org.jboss.weld.util.el.ForwardingMethodExpression.invoke(ForwardingMethodExpression.java:39)
at org.jboss.weld.el.WeldMethodExpression.invoke(WeldMethodExpression.java:50)
at com.sun.faces.facelets.el.TagMethodExpression.invoke(TagMethodExpression.java:105)
at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:88)
... 25 more
Caused by: javax.persistence.PersistenceException: org.hibernate.PropertyAccessException: could not get a field value by reflection getter of de.test.users.entities.User.userId
at org.hibernate.ejb.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1361)
at org.hibernate.ejb.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1289)
at org.hibernate.ejb.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1295)
at org.hibernate.ejb.AbstractEntityManagerImpl.persist(AbstractEntityManagerImpl.java:859)
at org.jboss.as.jpa.container.AbstractEntityManager.persist(AbstractEntityManager.java:563)
at de.test.users.service.UserManagerBean.createUser(UserManagerBean.java:31)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:601)
at org.jboss.as.ee.component.ManagedReferenceMethodInterceptorFactory$ManagedReferenceMethodInterceptor.processInvocation(ManagedReferenceMethodInterceptorFactory.java:72)
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:288)
at org.jboss.invocation.InterceptorContext$Invocation.proceed(InterceptorContext.java:374)
at org.jboss.as.weld.ejb.Jsr299BindingsInterceptor.doMethodInterception(Jsr299BindingsInterceptor.java:127)
at org.jboss.as.weld.ejb.Jsr299BindingsInterceptor.processInvocation(Jsr299BindingsInterceptor.java:135)
at org.jboss.as.ee.component.interceptors.UserInterceptorFactory$1.processInvocation(UserInterceptorFactory.java:36)
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:288)
at org.jboss.invocation.WeavedInterceptor.processInvocation(WeavedInterceptor.java:53)
at org.jboss.as.ee.component.interceptors.UserInterceptorFactory$1.processInvocation(UserInterceptorFactory.java:36)
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:288)
at org.jboss.as.jpa.interceptor.SBInvocationInterceptor.processInvocation(SBInvocationInterceptor.java:47)
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:288)
at org.jboss.as.weld.ejb.EjbRequestScopeActivationInterceptor.processInvocation(EjbRequestScopeActivationInterceptor.java:82)
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:288)
at org.jboss.invocation.InitialInterceptor.processInvocation(InitialInterceptor.java:21)
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:288)
at org.jboss.invocation.ChainedInterceptor.processInvocation(ChainedInterceptor.java:61)
at org.jboss.as.ee.component.interceptors.ComponentDispatcherInterceptor.processInvocation(ComponentDispatcherInterceptor.java:53)
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:288)
at org.jboss.as.ejb3.component.pool.PooledInstanceInterceptor.processInvocation(PooledInstanceInterceptor.java:51)
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:288)
at org.jboss.as.ejb3.tx.CMTTxInterceptor.invokeInOurTx(CMTTxInterceptor.java:228)
... 56 more
 Caused by: org.hibernate.PropertyAccessException: could not get a field value by reflection getter of de.test.users.entities.User.userId
at org.hibernate.property.DirectPropertyAccessor$DirectGetter.get(DirectPropertyAccessor.java:61)
at org.hibernate.tuple.entity.AbstractEntityTuplizer.getIdentifier(AbstractEntityTuplizer.java:341)
at org.hibernate.persister.entity.AbstractEntityPersister.getIdentifier(AbstractEntityPersister.java:4260)
at org.hibernate.persister.entity.AbstractEntityPersister.isTransient(AbstractEntityPersister.java:3982)
at org.hibernate.engine.internal.ForeignKeys.isTransient(ForeignKeys.java:209)
at org.hibernate.event.internal.AbstractSaveEventListener.getEntityState(AbstractSaveEventListener.java:509)
at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:118)
at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:78)
at org.hibernate.internal.SessionImpl.firePersist(SessionImpl.java:725)
at org.hibernate.internal.SessionImpl.persist(SessionImpl.java:701)
at org.hibernate.internal.SessionImpl.persist(SessionImpl.java:705)
at org.hibernate.ejb.AbstractEntityManagerImpl.persist(AbstractEntityManagerImpl.java:853)
... 84 more
 Caused by: java.lang.IllegalArgumentException: Can not set java.lang.Long field de.test.users.entities.User.userId to de.test.users.entities.User
at sun.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:164)
at sun.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:168)
at sun.reflect.UnsafeFieldAccessorImpl.ensureObj(UnsafeFieldAccessorImpl.java:55)
at sun.reflect.UnsafeObjectFieldAccessorImpl.get(UnsafeObjectFieldAccessorImpl.java:36)
at java.lang.reflect.Field.get(Field.java:372)
at org.hibernate.property.DirectPropertyAccessor$DirectGetter.get(DirectPropertyAccessor.java:58)
... 95 more

Any idea how I could resolve this? BTW, it seems that hibernate is not able to detect the classes in the jar file automatically. When i remove the class element from persistence.xml, the log tells me that hibernate didn't load any entities for the "users" persistence unit. Might that have something to do with the exception?

My project structure looks more or less like that:

project-ear
|-- lib
|-- META-INF
|   |
|   |-- maven
|   |-- persistence.xml
|   |-- application.xml
|
|-- users.jar
|
|-- users.war

Answer 1

I was able to resolve the issue by myself. I saw that the user.jar containing the entity bean was actually duplicated by Maven. It was placed in the lib folder of user.war as well as in the root lib folder in the ear package. I removed it from the lib folder of the war package and everything, including the class auto-detection by Hibernate, is working as expected now.

Answer 2

What is the datatype of userID? This part of the error:

Can not set java.lang.String field de.test.users.entities.User.userId to       
    de.test.users.entities.User

Leads me to believe it's a varchar or text. Try:

@Id
private String userId;

If that's the case.