NullPointerException when trying to access database

[pebbels]

Hi guys,

I got stick when trying to ccess the MySQl Database.
persistence.xml looks like this:
  

<persistence-unit name="fahrzeug_console" transaction-type="JTA">
      <provider>org.hibernate.ejb.HibernatePersistence</provider>
      <jta-data-source>java:/fahrzeug_consoleDatasource</jta-data-source>
      <properties>
         <property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect"/>
         <property name="hibernate.hbm2ddl.auto" value="validate"/>
         <property name="hibernate.show_sql" value="true"/>
         <property name="hibernate.format_sql" value="true"/>
         <property name="hibernate.transaction.manager_lookup_class" value="org.hibernate.transaction.JBossTransactionManagerLookup"/>
      </properties>
   </persistence-unit>   
</persistence>

And my code looks like this ( the problem occurs in queryVertraege() )

package com.console.beans;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;

import javax.ejb.Remove;
import javax.ejb.Stateful;
import javax.ejb.Stateless;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import javax.persistence.PersistenceContextType;

import org.hibernate.annotations.Entity;
import org.hibernate.annotations.Table;
import org.jboss.seam.annotations.Factory;
import org.jboss.seam.annotations.In;
import org.jboss.seam.annotations.Name;
import org.jboss.seam.annotations.Scope;
import org.jboss.seam.annotations.datamodel.DataModel;
import org.jboss.seam.annotations.security.Restrict;

import org.jboss.seam.ScopeType;

import com.console.doing.DBConnection;
import org.jboss.seam.security.Identity;


@Stateful
@Name("vertraege")
@Restrict("#{identity.loggedIn}")
public class Vertraege {
     

     @DataModel
     private List<Vertrag> vertraege = new ArrayList<Vertrag>();
     
     private int size;
     
     @PersistenceContext
     private EntityManager em;          

     public int getSize()               {     return size;     }

     public void setSize(int size)     {     
          this.size = size;
          System.out.print("size gesetzt: "+size);
     }     
     
     public void queryVertraege()     {
          vertraege = em.createQuery("select Fahrgestellnummer from _Vertrag").getResultList();
     }
     
     @Remove
     public void destroy()     {}
}

This is the bean

package com.console.beans;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Table;
import org.jboss.seam.annotations.Name;
import org.jboss.seam.annotations.datamodel.DataModel;

@Entity
//@Table(name="_Vertrag")
@Name("vertrag")
public class Vertrag implements Serializable{

     private int Fahrgestellnummer;
     private int id;
     private Date realesVertragsende;
     private Date regulaeresVertragsende;

    @Column(name="Fahrgestellnummer")
     public int getFahrgestellnummer() {
          return Fahrgestellnummer;
     }
     public void setFahrgestellnummer(int fahrgestellnummer) {
          Fahrgestellnummer = fahrgestellnummer;
     }
     @Id @GeneratedValue
    @Column(name="ID_Vertrag")
     public int getId() {
          return id;
     }
     public void setId(int id) {
          this.id = id;
     }
    @Column(name="Reales_Vertragsende")
     public Date getRealesVertragsende() {
          return realesVertragsende;
     }
     public void setRealesVertragsende(Date realesVertragsende) {
          this.realesVertragsende = realesVertragsende;
     }
    @Column(name="Regulaeres_Vertragsende")
     public Date getRegulaeresVertragsende() {
          return regulaeresVertragsende;
     }
     public void setRegulaeresVertragsende(Date regulaeresVertragsende) {
          this.regulaeresVertragsende = regulaeresVertragsende;
     }

     @Override
     public String toString(){          
          return "Vertrag " +id+ ": Reales Vertragsende " +realesVertragsende+ ", reguläres Vertragsende " +regulaeresVertragsende;
     }
}

the following exception is thrown:

12:24:40,812 FATAL [application] java.lang.NullPointerException
javax.faces.el.EvaluationException: java.lang.NullPointerException
     at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:91)
     at com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:91)
     at javax.faces.component.UICommand.broadcast(UICommand.java:383)
     at org.ajax4jsf.component.AjaxViewRoot.processEvents(AjaxViewRoot.java:184)
     at org.ajax4jsf.component.AjaxViewRoot.broadcastEvents(AjaxViewRoot.java:162)
     at org.ajax4jsf.component.AjaxViewRoot.processApplication(AjaxViewRoot.java:350)
     at com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:97)
     at com.sun.faces.lifecycle.LifecycleImpl.phase(LifecycleImpl.java:251)
     at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:117)
     at javax.faces.webapp.FacesServlet.service(FacesServlet.java:244)
     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
     at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:83)
     at org.jboss.seam.web.MultipartFilter.doFilter(MultipartFilter.java:85)
     at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
     at org.jboss.seam.web.ExceptionFilter.doFilter(ExceptionFilter.java:64)
     at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
     at org.jboss.seam.web.RedirectFilter.doFilter(RedirectFilter.java:45)
     at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
     at org.ajax4jsf.webapp.BaseXMLFilter.doXmlFilter(BaseXMLFilter.java:141)
     at org.ajax4jsf.webapp.BaseFilter.doFilter(BaseFilter.java:281)
     at org.jboss.seam.web.Ajax4jsfFilter.doFilter(Ajax4jsfFilter.java:60)
     at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
     at org.jboss.seam.web.LoggingFilter.doFilter(LoggingFilter.java:58)
     at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
     at org.jboss.seam.debug.hot.HotDeployFilter.doFilter(HotDeployFilter.java:68)
     at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
     at org.jboss.seam.servlet.SeamFilter.doFilter(SeamFilter.java:158)
     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
     at org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96)
     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
     at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:230)
     at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
     at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:179)
     at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:432)
     at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:84)
     at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
     at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
     at org.jboss.web.tomcat.service.jca.CachedConnectionValve.invoke(CachedConnectionValve.java:157)
     at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
     at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:262)
     at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844)
     at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583)
     at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:446)
     at java.lang.Thread.run(Thread.java:619)
Caused by: java.lang.NullPointerException
     at com.console.beans.Vertraege.queryVertraege(Vertraege.java:56)
     at com.console.beans.Login.login(Login.java:58)
     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:597)
     at org.jboss.seam.util.Reflections.invoke(Reflections.java:21)
     at org.jboss.seam.intercept.RootInvocationContext.proceed(RootInvocationContext.java:31)
     at org.jboss.seam.intercept.SeamInvocationContext.proceed(SeamInvocationContext.java:56)
     at org.jboss.seam.transaction.RollbackInterceptor.aroundInvoke(RollbackInterceptor.java:31)
     at org.jboss.seam.intercept.SeamInvocationContext.proceed(SeamInvocationContext.java:68)
     at org.jboss.seam.core.BijectionInterceptor.aroundInvoke(BijectionInterceptor.java:46)
     at org.jboss.seam.intercept.SeamInvocationContext.proceed(SeamInvocationContext.java:68)
     at org.jboss.seam.bpm.BusinessProcessInterceptor.aroundInvoke(BusinessProcessInterceptor.java:49)
     at org.jboss.seam.intercept.SeamInvocationContext.proceed(SeamInvocationContext.java:68)
     at org.jboss.seam.core.MethodContextInterceptor.aroundInvoke(MethodContextInterceptor.java:42)
     at org.jboss.seam.intercept.SeamInvocationContext.proceed(SeamInvocationContext.java:68)
     at org.jboss.seam.intercept.RootInterceptor.invoke(RootInterceptor.java:107)
     at org.jboss.seam.intercept.JavaBeanInterceptor.interceptInvocation(JavaBeanInterceptor.java:166)
     at org.jboss.seam.intercept.JavaBeanInterceptor.invoke(JavaBeanInterceptor.java:102)
     at com.console.beans.Login_$$_javassist_43.login(Login_$$_javassist_43.java)
     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:597)
     at org.jboss.el.util.ReflectionUtil.invokeMethod(ReflectionUtil.java:329)
     at org.jboss.el.util.ReflectionUtil.invokeMethod(ReflectionUtil.java:342)
     at org.jboss.el.parser.AstPropertySuffix.invoke(AstPropertySuffix.java:58)
     at org.jboss.el.parser.AstValue.invoke(AstValue.java:96)
     at org.jboss.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:276)
     at com.sun.facelets.el.TagMethodExpression.invoke(TagMethodExpression.java:68)
     at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:77)
     ... 46 more

     
Can somebody please tell me what is wrong?
Do I have to do any configurations?

Thanks Tina

[nickarls]

Your entitymanager isn't injected correcly? Show your components.xml, there might be a naming (em/entityManager) mismatch...

[pebbels]

thanks for your help!

This is my components.xml:

<?xml version="1.0" encoding="UTF-8"?>
<components xmlns="http://jboss.com/products/seam/components"
            xmlns:core="http://jboss.com/products/seam/core"
            xmlns:persistence="http://jboss.com/products/seam/persistence"
            xmlns:drools="http://jboss.com/products/seam/drools"
            xmlns:bpm="http://jboss.com/products/seam/bpm"
            xmlns:security="http://jboss.com/products/seam/security"
            xmlns:mail="http://jboss.com/products/seam/mail"
            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
            xsi:schemaLocation=
                "http://jboss.com/products/seam/core http://jboss.com/products/seam/core-2.0.xsd 
                 http://jboss.com/products/seam/persistence http://jboss.com/products/seam/persistence-2.0.xsd 
                 http://jboss.com/products/seam/drools http://jboss.com/products/seam/drools-2.0.xsd
                 http://jboss.com/products/seam/bpm http://jboss.com/products/seam/bpm-2.0.xsd
                 http://jboss.com/products/seam/security http://jboss.com/products/seam/security-2.0.xsd
                 http://jboss.com/products/seam/mail http://jboss.com/products/seam/mail-2.0.xsd
                 http://jboss.com/products/seam/components http://jboss.com/products/seam/components-2.0.xsd">

   <core:init debug="true" jndi-pattern="fahrzeug_console/#{ejbName}/local"/>
     
      
   <persistence:managed-persistence-context name="entityManager"
                                     auto-create="true"
                          entity-manager-factory="#{fahrzeug_consoleEntityManagerFactory}"/>

   <persistence:entity-manager-factory name="fahrzeug_consoleEntityManagerFactory" 
                      persistence-unit-name="fahrzeug_console"/>
   
   <drools:rule-base name="securityRules">
       <drools:rule-files><value>/security.drl</value></drools:rule-files>
   </drools:rule-base>

   <security:identity authenticate-method="#{authenticator.authenticate}"
                           security-rules="#{securityRules}"
                              remember-me="true"/>
                              
   <event type="org.jboss.seam.security.notLoggedIn">
       <action execute="#{redirect.captureCurrentView}"/>
   </event>
   <event type="org.jboss.seam.security.loginSuccessful">
       <action execute="#{redirect.returnToCapturedView}"/>
   </event>
   
   <mail:mail-session host="localhost" port="2525" username="test" password="test" />
        
   <!-- For use with jBPM pageflow or process management -->
     
   <bpm:jbpm>
      <bpm:process-definitions></bpm:process-definitions>
      <!-- <bpm:pageflow-definitions></bpm:pageflow-definitions> -->
   </bpm:jbpm>
   
      
</components>

I renamed the EntityManager in the code to entityManager but there is still a NullPointerException....

[christian.bauer]

Tina Kleb wrote on Mar 13, 2008 02:10 PM:

  <persistence:managed-persistence-context name="entityManager"
                                     auto-create="true"
                          entity-manager-factory="#{fahrzeug_consoleEntityManagerFactory}"/>

   <persistence:entity-manager-factory name="fahrzeug_consoleEntityManagerFactory" 
                      persistence-unit-name="fahrzeug_console"/>
   

This is not used at all if you apply @PersistenceContext injection through the EJB container. This configuration is for a Seam-managed and injected persistence context with @In. The docs are fairly extensive about both of these options.

[keithnaas]

You're mixing a Seam Managed Persistence Context with a Container Managed PC.  @PersistenceContext will inject the entity manager based on what is in persistence.xml.  If persistence.xml isn't configured to access the seam entity manager, NPEs will likely occur.

From 8.3. Seam-managed persistence contexts

Of course, you need to make sure that you have bound the EntityManagerFactory into JNDI. In JBoss, you can do this by adding the following property setting to persistence.xml.

<property name="jboss.entity.manager.factory.jndi.name" 
          value="java:/EntityManagerFactories/bookingData"/>

Now we can have our EntityManager injected using:

@In EntityManager bookingDatabase;

[christian.bauer]

And from the stacktrace it looks to me like you are not even using an EJB container, so @Stateful and @PersistenceContext and all the rest have absolutely no effect...

[pebbels]

first: thanks @all!

now i am totally confused!
i had a look at the seam userguide chapter 1.6 because i have to query the database (do not query the databse for processes or instances) and show the results. To use rowCount i thought i need @Persistence Context like

<h:dataTable id="hotels" value="#{hotels}" var="hot" rendered="#{hotels.rowCount>0}">

but i could not found any configuration in the persistence.xml or components.xml of the project...

so can you tell what's right and what's wrong?

[keithnaas]

It might be clearer after reading up on Seam managed PersistenceContexts.

Sounds like you want to use @In EntityManager entityManager instead of @PersistenceContext Entitymanager entityManager. 

Good luck,
keith