RequestContext won't work

问题

I am having trouble to update the view from the bean in the back using PrimeFaces's RequestContext. In the example below I have a button and 2 panels. When pressing the button, I want to update one panel, but not the other one. It does not work though and I can't find the error! requestContext.update("panela"); is fired, but doesn't do its job! Help greatly appreciated!

The XHTML file:

<!DOCTYPE html>
<html xmlns="http://www.w3c.org/1999/xhtml"
      xmlns:h="http://java.sun.com/jsf/html"
      xmlns:p="http://primefaces.org/ui"
      xmlns:f="http://xmlns.jcp.org/jsf/core">
    <h:head/>
    <h:body>
        <h:form>
            <p:panelGrid columns="1">
                <p:commandButton value="Save" actionListener="#{runtimeUpdatesBean.save}" />
                <p:panel id="panela">
                    <h:outputText value="#{runtimeUpdatesBean.texta}"/>
                </p:panel>
                <p:panel id="panelb">
                    <h:outputText value="#{runtimeUpdatesBean.textb}"/>
                </p:panel>
            </p:panelGrid>
        </h:form>
    </h:body>
</html>

The bean:

package com.glasses.primework;

import javax.faces.bean.ManagedBean;
import javax.faces.bean.SessionScoped;
import org.primefaces.context.RequestContext;

@ManagedBean
@SessionScoped
public class RuntimeUpdatesBean {
    private String texta;
    private String textb;
    private boolean outcome;

    public String getTexta() {
        texta += "a";
        System.out.println("RuntimeUpdatesBean.getTexta() = " + texta);
        return texta;
    }

    public String getTextb() {
        textb += "b";
        System.out.println("RuntimeUpdatesBean.getTextb() = " + textb);
        return textb;
    }

    public void save() {
        RequestContext requestContext = RequestContext.getCurrentInstance();

        if(outcome) {
            System.out.println("RuntimeUpdatesBean.save() = update panela");
            requestContext.update("panela");
            outcome = false;
        } else {
            System.out.println("RuntimeUpdatesBean.save() = update panelb");
            requestContext.update("panelb");
            outcome = true;
        }
    }
}

回答1:

Well the problem is the ID of the component that you are referring.
In JSF when you place a component inside h:form (or Some Primefaces components like TabView), that component's Id will be generated based on the h:form id too.
Here is the Example:

<h:form id="panelaForm">
   <p:panel id="panela">
       ....
   </p:panel>
</h:form>

In the above case your p:panel's id will be generated as panelaForm:panela.
In your case since you haven't provided any ID for h:form a dynamic id will be attached like for example j_xyz:panela(you can see it using you browser's Inspect Element).

So If you wan to access p:panel with Id panela inside the same h:form then no need to attach the form Id.
But If you want to access the p:panel outside h:form then you need to attach the h:form id to access it.

Solution to you problem is: use an custom ID to your h:form (which is a best practice by the way..) and access the p:panel by attaching that form ID.

<h:form id="panelaForm">
   <p:panel id="panela">
       ....
   </p:panel>
</h:form>

And in Managed bean use:

RequestContext.getCurrentInstance().update("panelaForm:panela");

回答2:

I'm the new guy here (Java EE) however below solution works for me:

<!DOCTYPE html>
<html   xmlns="http://www.w3c.org/1999/xhtml"
    xmlns:h="http://java.sun.com/jsf/html"
    xmlns:p="http://primefaces.org/ui"
    xmlns:f="http://xmlns.jcp.org/jsf/core">
<h:head/>
<h:body>
    <h:form id="form">
        <p:panelGrid columns="1">
            <p:commandButton value="Save" actionListener="#{runtimeUpdatesBean.save}" update=":form" />
            <p:panel id="panela">
                <h:outputText value="#{runtimeUpdatesBean.texta}"/>
            </p:panel>
            <p:panel id="panelb">
                <h:outputText value="#{runtimeUpdatesBean.textb}"/>
            </p:panel>
        </p:panelGrid>
    </h:form>
</h:body>

来源：https://stackoverflow.com/questions/27212481/requestcontext-wont-work

标签

jsf

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primefaces

requestcontext