Question

I try to make 2 h:selectOneMenu component on the page. When I choose some subject from the first selectOneMenu I want to use ajax with listener where I get id selected subject and fill list tests for this subject in other selectOneMenu. I use bean with session scoped.

<f:event type="preRenderView" listener="#{test.getAllSubjects}" />
<h:form prependId="false">          
    <h:panelGroup rendered="#{not empty test.testBean.subjectList}">
                    <h:selectOneMenu value="#{test.testBean.subjectId}" id="subjects">
                        <f:selectItem itemLabel="--Select a subject--" itemValue="0" />
                        <f:selectItems value="#{test.testBean.subjectList}"
                            var="subjectItem" itemValue="#{subjectItem.subjectId}"
                            itemLabel="#{subjectItem.subject}" />
                        <f:ajax event="change" render="tests" listener="#{test.testsBySubjectId}" />                
                    </h:selectOneMenu>

    <h:selectOneMenu value="#{test.testBean.test.testIdentifer.testId}" id="tests">
                    <f:selectItem itemLabel="--Select a test--" itemValue="0" />
                        <f:selectItems value="#{test.testBean.testList}" var="testItem" 
                        itemValue="#{testItem.testIdentifer.testId}" itemLabel="#{testItem.testName}" />                                    
                    </h:selectOneMenu>
    </h:panelGroup>
</h:form> 

And in managed bean Use next listener

public void getTestsBySubjectId() throws DAOException {
     Long subjectId = testBean.getSubjectId();
     List<Test> testList = testBo.getTestBySubjectId(subjectId);
     testBean.setTestList(testList);
     }

But this listener will never be called.

That’s why I made some tricks I change tag as <f:ajax event="change" render="tests" /> without listener.

But in h:selectOneMenu for test I did

<f:selectItems value="#{test.testsBySubjectId}" var="testItem"
                        itemValue="#{testItem.testIdentifer.testId}"
                        itemLabel="#{testItem.testName}" /> 

And there I initialize value not values tests from bean test list. I try to init as

public List<Test> getTestsBySubjectId() throws DAOException {
        Long subjectId = testBean.getSubjectId();
        List<Test> testList = testBo.getTestBySubjectId(subjectId);
        testBean.setTestList(testList);
        return testList;
    } 

This variant works. But I don’t understand why previous variant with listener doesn’t work.

Where is my fault? And what should be changed for right result?

Answer 1

@SJuan76 You are right. With name of listener but I understand my real problem.

<f:event type="preRenderView" listener="#{test.getAllSubjects}" />

This listener calls on ajax postback. I understand this from this article.Is it possible to disable f:event type=“preRenderView” listener on postback?

Thanks @BalusC

And I also add arg AjaxBehaviorEvent eventin listener method