Tomahawk DataScroller - NullPointerException with navigation panel

Question

Hi all,
I'm trying to implement navigation on a dataTable with DataScroller. Except from the dataTable content the jsp is a copy / paste from the tomahawk cars example.
My jsp structure has 3 main elements
- datatable
- scroller one for datatable navigation (next, previous, ...)
- scroller two for datatable statistics (pages counts)
When page is loaded there is a fatal error (NullPointerException)
If I delete the scroller one definition in my jsp there is no error, data table is correctly populated with 10 first rows and scroller two information is correct.
I tried with a simple ArrayList or with a DataModel in my backing bean. In both cases the NullPointerException happens.
I checked web.xml, faces-config, ... can't find a reason.
Any idea someone please? See stacktrace here under and sample of my jsp
Thank you very much for any help.
sunjavero
// here is my jsp extract:
<code>
<f:view>
<h:panelGroup id="body">
     <t:dataTAble id="data" ... >
     </t:dataTable>
     <h:panelGrid columns="1" ... >
          <t:dataScroller id="scroll_1" for="data" ... >
               <f:facet name="first" >
                    <t:graphicImage url="images/arrow-first.gif" border="1" />
               </f:facet>
               // (other facets same principle...)
          </t:dataScroller>
          <t:dataScroller id="scroll_2" for="data" ... >
     <h:outputFormat ... >
                    <f:param value="#{rowsCount}" />
                    <f:param value="#{displayedRowsCountVar}" />
                    <f:param value="#{firstRowIndex}" />
                    <f:param value="#{lastRowIndex}" />
                    <f:param value="#{pageIndex}" />
                    <f:param value="#{pageCount}" />
               </h:outputFormat>
          </t:dataScroller>
     </h:panelGrid>
</h:panelGroup>
</f:view>
</code>
exception:
org.apache.jasper.JasperException: javax.servlet.jsp.JspException: null
     org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:510)
     org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:375)
     org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:314)
     org.apache.jasper.servlet.JspServlet.service(JspServlet.java:264)
     javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
     org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:362)
caused by (root error?):
java.lang.NullPointerException
     com.sun.faces.renderkit.html_basic.CommandLinkRenderer.getHiddenFieldName(CommandLinkRenderer.java:136)
     com.sun.faces.renderkit.html_basic.CommandLinkRenderer.encodeEnd(CommandLinkRenderer.java:318)
     javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:720)
     org.apache.myfaces.custom.datascroller.HtmlDataScrollerRenderer.renderFacet(HtmlDataScrollerRenderer.java:294)
     org.apache.myfaces.custom.datascroller.HtmlDataScrollerRenderer.renderScroller(HtmlDataScrollerRenderer.java:236)
     org.apache.myfaces.custom.datascroller.HtmlDataScrollerRenderer.encodeEnd(HtmlDataScrollerRenderer.java:207)

Answer 1

Hi all,
I found out a solution (after many hours of cursing!): Better to enclose DataScroller inside a form.
I don't understand why tomahawk example works fine without it (!!!)
If someone has an explanation he is welcome
And if someone explains me how to get more than 24 lines of stacktrace on windows 98 he is welcome too! (Unable to start tomcat from IDE because of wrong memory size), so have to start it from dos...
Sincerely yours... tired sunjavero