My app needs to render a list of questions whose type is database-driven. I'm using a few facelets TagHandlers to accomplish this. The view looks like this: | <s:validateAll> | | <f:facet name="aroundInvalidField"> | <s:span styleClass="errors"/> | </f:facet> | | <h:panelGrid id="questionPanel" columns="3"> | | <crs:customQuestions | registrationType="#{registrationType}" | questionTextVar="questionText" | questionNumberVar="i" | requiredVar="required"> | | | <h:outputLabel for="answerInput#{i}" value="#{i}" id="questionNumber#{i}"/> | | <s:formattedText value="#{questionText}" id="questionText#{i}"/> | | <h:panelGroup> | <s:decorate> | <crs:isText> | <h:inputText id="answerInput#{i}" | value="#{registrationProcess.pageAnswers[ i].valueString}" | required="#{required}"> | <a:support event="onblur" reRender="questionErrors#{i}"/> | </h:inputText> | </crs:isText> | | <crs:isDate> | <h:inputText id="answerInput#{i}" | value="#{registrationProcess.pageAnswers[ i].valueDate}" | required="#{required}"> | <s:convertDateTime pattern="MM/dd/yyyy"/> | <a:support event="onblur" reRender="questionErrors#{i}"/> | </h:inputText> | <s:selectDate for="answerInput#{i}"> | <h:graphicImage url="img/dtpick.gif" style="margin-left:5px"/> | </s:selectDate> | </crs:isDate> | | <crs:isBoolean> | <h:selectBooleanCheckbox | id="answerInput#{i}" | value="#{registrationProcess.pageAnswers[ i].valueBoolean}" | required="${required}"/> | </crs:isBoolean> | | <br clear="none"/> | <a:outputPanel id="questionErrors#{i}"> | <s:message/> | </a:outputPanel> | </s:decorate> | </h:panelGroup> | | </crs:customQuestions> | </h:panelGrid> | </s:validateAll> | And the main taghandler (which I modeled after facelets' ForEachHandler) looks like this: | public class CustomQuestionTagHandler extends TagHandler { | | private final TagAttribute registrationType; | private final TagAttribute questionTextVar; | private final TagAttribute questionNumberVar; | private final TagAttribute requiredVar; | | public CustomQuestionTagHandler(TagConfig config) { | super(config); | registrationType = getRequiredAttribute("registrationType"); | questionTextVar = getRequiredAttribute("questionTextVar"); | questionNumberVar = getRequiredAttribute("questionNumberVar"); | requiredVar = getRequiredAttribute("requiredVar"); | } | | @SuppressWarnings("unchecked") | public void apply(FaceletContext faceletContext, UIComponent parent) throws IOException, FacesException, | FaceletException, ELException { | RegistrationType registrationType = (RegistrationType) this.registrationType.getObject(faceletContext, | RegistrationType.class); | assert registrationType != null; | List<QuestionUsage> questionUsages = registrationType.getQuestionUsages(); | assert questionUsages != null; | | String questionTextVar = this.questionTextVar.getValue(faceletContext); | String questionNumberVar = this.questionNumberVar.getValue(faceletContext); | String requiredVar = this.requiredVar.getValue(faceletContext); | | VariableMapper variables = faceletContext.getVariableMapper(); | | int i = 1; | for (QuestionUsage questionUsage : questionUsages) { | Question question = questionUsage.getQuestion(); | Integer questionNumber = new Integer(i); | | ValueExpression questionNumberValueExpression = faceletContext.getExpressionFactory() | .createValueExpression(questionNumber, Integer.class); | variables.setVariable(questionNumberVar, questionNumberValueExpression); | | ValueExpression questionTextValueExpression = faceletContext.getExpressionFactory().createValueExpression( | question.getText(), String.class); | variables.setVariable(questionTextVar, questionTextValueExpression); | | Boolean required = questionUsage.isRequired(); | variables.setVariable(requiredVar, faceletContext.getExpressionFactory().createValueExpression(required, | Boolean.class)); | | | faceletContext.setAttribute("questionType", question.getType()); | | // execute body | this.nextHandler.apply(faceletContext, parent); | | i++; | } | } | | } | This renders fine. But during the onblur ajax validation check, this occurs: | java.lang.NullPointerException | at org.jboss.seam.core.Expressions.getValidator(Expressions.java:198) | at org.jboss.seam.core.Expressions.validate(Expressions.java:182) | at org.jboss.seam.ui.ModelValidator.validate(ModelValidator.java:25) | at javax.faces.component._ComponentUtils.callValidators(_ComponentUtils.java:157) | at javax.faces.component.UIInput.validateValue(UIInput.java:312) | at javax.faces.component.UIInput.validate(UIInput.java:353) | at javax.faces.component.UIInput.processValidators(UIInput.java:183) | at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:624) | at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:624) | at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:624) | at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:624) | at javax.faces.component.UIForm.processValidators(UIForm.java:70) | at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:624) | at javax.faces.component.UIViewRoot.processValidators(UIViewRoot.java:146) | at org.ajax4jsf.framework.ajax.AjaxViewRoot.processValidators(AjaxViewRoot.java:389) | ... | It appears that Expressions.validate(...) is trying to evaluate #{registrationProcess.pageAnswers[ i].valueString}, which returns null. I don't know enough about EL to know why. I suspect either I can't use model validation this way, or I need to do something special in my TagHandler. Does anyone have any recommendations? Also, a null-check should probably be put in Expressions.java (line 198ish) before calling getValidator(). Thanks! View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4021364#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...