Question

I am using JSF 2.0 and Primefaces 3.4.2, I have a datatable populated using lazy load.

When I view scope for managedbean, then datatable selectedRow gives null pointer exception.
If I use session scope then I could get selectedRow in managedbean.

I am using CDI Spring annotations for specifying scope. I have used this method to create view scope.

Update 1

I have noticed another thing is using view scope when I paginate to second page and then comes back to first page, then I could get the selectedRow. If I select a row without paginating then I get null pointer exception.

JSF Page

<p:dataTable id="dataTable" var="req" lazy="true" value="#{emp.lazyModel}"
                paginator="true" rows="10" 
                             selection="#{emp.selectedRequest}"
                            selectionMode="single">                         
          <p:ajax event="rowSelect" listener="#{emp.onRowSelect}" />  

ManagedBean

@Named("emp")
@Scope("view")
public class EmployeesManagedBean implements Serializable {

    @PostConstruct
    public void init() {
        initTable();
    }

    private void initTable() {
        lazyModel = new LazyRequestDataModel(requestList, requestService);
    }

    public LazyDataModel<Employee> getLazyModel() {
        return lazyModel;

    }

I am getting nullpointer exception at this line in onRowSelect method

 Emp emp = (Emp) event.getObject()); 
 System.out.println(emp.getEmpNo() );

Full error stacktrace

java.lang.NullPointerException
    at net.test.managed.bean.RequestManagedBean.onRowSelect(RequestManagedBean.java:134)
    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 com.sun.el.parser.AstValue.invoke(AstValue.java:187)
    at com.sun.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:297)
    at org.primefaces.component.behavior.ajax.AjaxBehaviorListenerImpl.processAjaxBehavior(AjaxBehaviorListenerImpl.java:52)
    at org.primefaces.event.SelectEvent.processListener(SelectEvent.java:40)
    at javax.faces.component.behavior.BehaviorBase.broadcast(BehaviorBase.java:106)
    at javax.faces.component.UIComponentBase.broadcast(UIComponentBase.java:760)
    at javax.faces.component.UIData.broadcast(UIData.java:1071)
    at javax.faces.component.UIData.broadcast(UIData.java:1093)
    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 weblogic.servlet.internal.StubSecurityHelper$ServletServiceAction.run(StubSecurityHelper.java:227)
    at weblogic.servlet.internal.StubSecurityHelper.invokeServlet(StubSecurityHelper.java:125)
    at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:301)
    at weblogic.servlet.internal.TailFilter.doFilter(TailFilter.java:26)
    at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:56)
    at weblogic.servlet.internal.RequestEventsFilter.doFilter(RequestEventsFilter.java:27)
    at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:56)
    at weblogic.servlet.internal.WebAppServletContext$ServletInvocationAction.wrapRun(WebAppServletContext.java:3730)
    at weblogic.servlet.internal.WebAppServletContext$ServletInvocationAction.run(WebAppServletContext.java:3696)
    at weblogic.security.acl.internal.AuthenticatedSubject.doAs(AuthenticatedSubject.java:321)
    at weblogic.security.service.SecurityManager.runAs(SecurityManager.java:120)
    at weblogic.servlet.internal.WebAppServletContext.securedExecute(WebAppServletContext.java:2273)
    at weblogic.servlet.internal.WebAppServletContext.execute(WebAppServletContext.java:2179)
    at weblogic.servlet.internal.ServletRequestImpl.run(ServletRequestImpl.java:1490)
    at weblogic.work.ExecuteThread.execute(ExecuteThread.java:256)
    at weblogic.work.ExecuteThread.run(ExecuteThread.java:221)

Answer 1

I have managed to resolve this issue by using @ViewAccessScoped which is supported in CDI. Add the dependency in maven or directly download from http://myfaces.apache.org/extensions/cdi/download.html and put it in classpath.

<dependency>
    <groupId>org.apache.myfaces.extensions.cdi.core</groupId>
    <artifactId>myfaces-extcdi-core-api</artifactId>
    <version>1.0.5</version>
    <scope>compile</scope>
</dependency>

One small problem still remains i.e. when application is deployed for the first time, I still do not get selected row value, for the subsequent selections I am able to get selected row value.