小编典典

h:selectOneMenu中的f:ajax侦听器方法未执行

ajax

在托管bean中使用适当的值正确生成了页面,但是这两个h:selectOneMenus中的ajax事件不起作用。不调用侦听器。标签内一定有错误,但我看不到。

<f:view>
    <h:form>
        <h:messages />
        <h:panelGrid columns="3">

            <h:outputLabel value="Choose your faculty: *" for="faculties" />
            <h:selectOneMenu id="faculties" value="#{registrateStudent.selectedFaculty}" >
                <f:ajax event="change" listener="#{registrateStudent.genSpecializations}" execute="faculties" render="specializations" />                        
                <f:selectItems value="#{registrateStudent.listFaculty}" var="curFac" itemLabel="#{curFac.name}" itemValue="#{curFac}" />
            </h:selectOneMenu>
            <h:message id="message_faculties" for="faculties" />

            <h:outputLabel value="Choose your specialization: *" for="specializations" />
            <h:selectOneMenu id="specializations" value="#{registrateStudent.selectedSpecialization}" >
                <f:selectItems value="#{registrateStudent.listSpecialization}" var="curSpec" itemLabel="#{curSpec.name}" itemValue="#{curSpec}"/>
            </h:selectOneMenu>
            <h:message id="message_specializations" for="specializations" />

托管Bean:

@ManagedBean(name = "registrateStudent")
@ViewScoped
public class RegistrateStudent {


    private Faculty selectedFaculty;
    private List<Faculty> listFaculty;
    private Specialization selectedSpecialization;
    private List<Specialization> listSpecialization;
    private boolean showSpecialization = false;


    /** Creates a new instance of RegistrateStudent */
    public RegistrateStudent() {
        users = new Users();
        System.out.println("poaposd1");
        student = new Student();
    }

    @PostConstruct
    public void init() {
        listFaculty = ff.findAll();
        if (listFaculty != null) {
            selectedFaculty = listFaculty.get(0);
            listSpecialization = sf.findByFaculty(selectedFaculty.getIdFaculty());
            if (listSpecialization != null) {
                selectedSpecialization = listSpecialization.get(0);
            }
            else {}
        } else {}
    }

   public void genSpecializations(AjaxBehaviorEvent event) {
        if (sf.findByFaculty(selectedFaculty.getIdFaculty()) != null) {
            this.showSpecialization = true;
        } else {
            JsfUtil.addSuccessMessage("faculties", "We don't have specializations for such faculty");
        }
    }
}

更新:

我发现了一些有趣的东西:

<f:ajax>标签不工作<h:link><h:selectOneMenu><h:button><h:commandButton>。在这种情况下,render不会注意到event属性中的错误值,但是属性的错误值会产生错误。

<h:outputLabel><h:inputText>可以<f:ajax>正常使用


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2020-07-26

共1个答案

小编典典

<f:ajax>要求jsf.js包含在HTML文件之中<head>。它包含用于执行JSF ajax魔术的所有JS函数。

为此,请确保在主模板中使用<h:head>而不是<head>。然后,JSF将自动在其中包含<script>指向的必要元素jsf.js

<!DOCTYPE html>
<html lang="en"
    xmlns="http://www.w3.org/1999/xhtml"
    xmlns:f="http://java.sun.com/jsf/core"
    xmlns:h="http://java.sun.com/jsf/html"
    xmlns:ui="http://java.sun.com/jsf/facelets">
    <h:head>
        <title>Look, with h:head</title>
    </h:head>
    <h:body>
        Put your content here.
    </h:body>
</html>

请注意,在带有Firefox的Web Developer Toolbar和/或FirebugWeb开发人员工具集的Web浏览器中,您应该立即注意到JS错误,例如jsf is undefined将执行ajax请求时。至少应该考虑一下。


更新 :根据您的更新

我发现了一些有趣的东西:

<f:ajax>标签不工作<h:link><h:selectOneMenu><h:button><h:commandButton>。在这种情况下,render不会注意到event属性中的错误值,但是属性的错误值会产生错误。

<h:outputLabel><h:inputText>可以<f:ajax>正常使用。

<h:link><h:button>被intented的GET请求,不是POST请求。但是,它应该在<h:selectOneMenu>和上都可以正常工作<h:commandButton>。为了简化起见,您没有在问题中省略完整代码的更多代码吗?您正在使用哪个JSF展示/版本?您是否在classpath中使用了正确的库?看来您确实必须弄乱了某些东西。

为了说服您(和我自己),我刚刚创建了以下副本’n’paste’n’runnable测试用例

<!DOCTYPE html>
<html lang="en"
    xmlns:h="http://java.sun.com/jsf/html" 
    xmlns:f="http://java.sun.com/jsf/core"
    xmlns:ui="http://java.sun.com/jsf/facelets"
>
    <h:head>
        <title>SO question 6089924</title>
    </h:head>
    <h:body>
        <h:form>
            <h:selectOneMenu value="#{bean.selected}">
                <f:selectItem itemValue="#{null}" itemLabel="Select..." />
                <f:selectItem itemValue="one" />
                <f:selectItem itemValue="two" />
                <f:selectItem itemValue="three" />
                <f:ajax listener="#{bean.listener}" render="result" />
            </h:selectOneMenu>

            <h:commandButton value="commandButton" action="#{bean.submit}">
                <f:ajax listener="#{bean.listener}" render="result" />
            </h:commandButton>

            <h:outputText id="result" value="#{bean.selected} #{bean.result}" />

            <h:messages />
        </h:form>
    </h:body>
</html>

用这个豆

package com.example;

import java.io.Serializable;

import javax.faces.bean.ManagedBean;
import javax.faces.bean.ViewScoped;
import javax.faces.event.AjaxBehaviorEvent;

@ManagedBean
@ViewScoped
public class Bean implements Serializable {

    private String selected;
    private String result;

    public void submit() {
        System.out.println("submit");
    }

    public void listener(AjaxBehaviorEvent event) {
        System.out.println("listener");
        result = "called by " + event.getComponent().getClass().getName();
    }

    public String getSelected() {
        return selected;
    }

    public void setSelected(String selected) {
        this.selected = selected;
    }

    public String getResult() {
        return result;
    }

}

它与Mojarra 2.1.1在Tomcat 7.0.12上运行良好。

INFO: Starting Servlet Engine: Apache Tomcat/7.0.12
INFO: Initializing Mojarra 2.1.1 (FCS 20110408) for context '/playground'
2020-07-26