<p:dataList value="#{questionBean.questionsForums}" var="quests" itemType="none"> <p:panel > <f:facet name="header"> <h:outputText value="#{quests.nbupvote}" style="margin-right:30px;color:#cdcdcd" class="voteBox" /> <h:outputText class="font-custom" value="#{quests.titre}" /> </f:facet> <h:link value="Consulter Détails"> <f:param name="quesId" value="#{quests.quesPk}" converter="javax.faces.Long">  <f:convertNumber longOnly="true" /> </f:param> </h:link> </p:panel> </p:dataList> 

 @ManagedProperty(value="#{param.quesId}") private Long quesPk;   public Question questionDetail(){    Question detail=qDao.selectDetail(quesPk);  return detail;   }  

  2014-01-15T20:32:02.606+0100|Avertissement: StandardWrapperValve[Faces Servlet]: Servlet.service() for servlet Faces Servlet threw exception  javax.faces.view.facelets.TagException: /forum.xhtml @77,44 <f:convertNumber> Parent not an instance of ValueHolder: javax.faces.component.UIParameter@27a898f7 at com.sun.faces.facelets.tag.jsf.ConverterTagHandlerDelegateImpl.apply(ConverterTagHandlerDelegateImpl.java:88) at javax.faces.view.facelets.DelegatingMetaTagHandler.apply(DelegatingMetaTagHandler.java:120) at javax.faces.view.facelets.DelegatingMetaTagHandler.applyNextHandler(DelegatingMetaTagHandler.java:137) at com.sun.faces.facelets.tag.jsf.ComponentTagHandlerDelegateImpl.apply(ComponentTagHandlerDelegateImpl.java:190) at javax.faces.view.facelets.DelegatingMetaTagHandler.apply(DelegatingMetaTagHandler.java:120) at javax.faces.view.facelets.DelegatingMetaTagHandler.applyNextHandler(DelegatingMetaTagHandler.java:137) at com.sun.faces.facelets.tag.jsf.ComponentTagHandlerDelegateImpl.apply(ComponentTagHandlerDelegateImpl.java:190) at javax.faces.view.facelets.DelegatingMetaTagHandler.apply(DelegatingMetaTagHandler.java:120) 

 <p:dataList value="#{questionBean.questionsForums}" var="quests" itemType="none"> <p:panel > <f:facet name="header"> <h:outputText value="#{quests.nbupvote}" style="margin-right:30px;color:#cdcdcd" class="voteBox" /> <h:outputText class="font-custom" value="#{quests.titre}" /> </f:facet> <h:link value="Consulter Détails" outcome="question">   <f:param name="quesId" value="#{quests.quesPk}" > </f:param>  </h:link> </p:panel> </p:dataList> 

 private String quesPk; private Question detailQuestion; public Question getDetailQuestion() { return detailQuestion=qDao.selectDetail(Long.valueOf(quesPk)); }  public void setDetailQuestion(Question detailQuestion) {  this.detailQuestion = detailQuestion; } 

 2014-01-16T21:11:22.145+0100|Grave: Error Rendering View[/question.xhtml]  javax.el.ELException: /question.xhtml @52,24 value="#{questionBean.detailQuestion}": java.lang.NumberFormatException: null at com.sun.faces.facelets.el.TagValueExpression.getValue(TagValueExpression.java:114) at javax.faces.component.ComponentStateHelper.eval(ComponentStateHelper.java:194) at javax.faces.component.ComponentStateHelper.eval(ComponentStateHelper.java:182) at javax.faces.component.UIData.getValue(UIData.java:732)   Caused by: javax.el.ELException: java.lang.NumberFormatException: null at javax.el.BeanELResolver.getValue(BeanELResolver.java:368) at com.sun.faces.el.DemuxCompositeELResolver._getValue(DemuxCompositeELResolver.java:176) at com.sun.faces.el.DemuxCompositeELResolver.getValue(DemuxCompositeELResolver.java:203) at com.sun.el.parser.AstValue.getValue(AstValue.java:140) at com.sun.el.parser.AstValue.getValue(AstValue.java:204) at com.sun.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:226) at org.jboss.weld.el.WeldValueExpression.getValue(WeldValueExpression.java:50) at com.sun.faces.facelets.el.TagValueExpression.getValue(TagValueExpression.java:109) ... 53 more Caused by: java.lang.NumberFormatException: null at java.lang.Long.parseLong(Long.java:404) at java.lang.Long.valueOf(Long.java:540) at com.portail.managedBeans.QuestionBean.getDetailQuestion(QuestionBean.java:33) 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:606) 2014-01-16T21:11:22.220+0100|Avertissement: StandardWrapperValve[Faces Servlet]: Servlet.service() for servlet Faces Servlet threw exception  java.lang.NumberFormatException: null at java.lang.Long.parseLong(Long.java:404) at java.lang.Long.valueOf(Long.java:540) at com.portail.managedBeans.QuestionBean.getDetailQuestion(QuestionBean.java:33) 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:606) at javax.el.BeanELResolver.getValue(BeanELResolver.java:363) 

And this is the code of the details of the question

 <h:head> <f:metadata> <f:viewParam name="quesId" value="#{questionBean.quesPk}" converter="javax.faces.Long" /> </f:metadata> </h:head> <h:form> <p:dataList value="#{questionBean.detailQuestion}" var="quests" itemType="none"> <h:outputText value="1" style="margin-right:30px;color:#cdcdcd" class="voteBox" /> <h3><h:outputText class="font-custom" value="#{quests.titre}" /></h3><br/><p:separator></p:separator> <h:outputText class="font-custom" value="#{quests.contenu}" /> <div class="navfooter" style="margin-left: 20%"> <ul> <li><a href="profil.xhtml">Modifier</a></li> <li style="margin-left: 40%">Auteur</li> </ul> </div> </p:dataList>