如何通过ajax刷新由JSF填充的javascript变量？ [英] How can I refresh a javascript variable, populated by JSF, via ajax?

问题描述

我想要执行以下操作：

1. 从中选择一项h：selectOneMenu


2. 使用新值通过ajax更新支持bean


3. 使用新值运行Javascript函数

在下面的代码中， alert（＃{backingBean.derivedValue}）仍包含来自的值最后一次更改（即当我选择Two时为0，当我选择One时为4，依此类推）：

In the following code though, alert(#{backingBean.derivedValue}) still contains the value from the last change (i.e. it's 0 when I select "Two", 4 when I select "One", and so on):

<h:form>
    <h:selectOneMenu value="#{backingBean.input1}">
        <f:selectItem itemLabel="One" itemValue="1"/>
        <f:selectItem itemLabel="Two" itemValue="2"/>
        <f:ajax render="@form" onevent="function(data) { if (data.status === 'success') { alert(#{backingBean.derivedValue}) }}"/>
    </h:selectOneMenu>

    Input value: #{backingBean.input1}
    Derived value: #{backingBean.derivedValue}
</h:form>

支持豆：

@ManagedBean
@ViewScoped
public class BackingBean {

    private int input1;
    private int derivedValue;

    public int getDerivedValue() {
        return derivedValue;
    }

    public void setDerivedValue(int derivedValue) {
        this.derivedValue = derivedValue;
    }

    public int getInput1() {
        return input1;
    }

    public void setInput1(int input1) {
        this.input1 = input1;
        derivedValue = input1 * 2;
    }
}

有没有办法做到这一点？ （顺便说一句，我在这个网站上读过无数线程，这种线程与JSF / ajax / javascript协同工作，但不是这个特定的问题）

Is there a way to do this? (BTW, I've read countless threads on this site which kind of/sort of deal with JSF/ajax/javascript working together, but not this specific issue)

推荐答案

我成功实现了本答案中提出的解决方案，使用Javascript获取支持bean值它使用 PrimeFace的RequestContext 添加Javascript回调参数服务器端。

I had success implementing the solution proposed in this answer, Getting backing bean value with Javascript which uses PrimeFace's RequestContext to add a Javascript callback parameter server-side.

这是我的Facelets页面：

Here is my Facelets page:

<h:form>
    <p:selectOneMenu value="#{backingBean.input1}">
        <f:selectItem itemLabel="One" itemValue="1"/>
        <f:selectItem itemLabel="Two" itemValue="2"/>
        <p:ajax oncomplete="afterLoad(xhr, status, args)"/>
    </p:selectOneMenu>
    <h:outputScript>
        function afterLoad(xhr, status, args) {    
          alert("Input * 2 = " + args.derived);
        }
    </h:outputScript>
</h:form>

这是我的支持豆：

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

@ManagedBean
@ViewScoped
public class BackingBean {

    private int input1;
    private int derivedValue;

    public int getDerivedValue() {
        return derivedValue;
    }

    public void setDerivedValue(int derivedValue) {
        this.derivedValue = derivedValue;
    }

    public int getInput1() {
        return input1;
    }

    public void setInput1(int input1) {
        this.input1 = input1;
        derivedValue = input1 * 2;
        RequestContext.getCurrentInstance().addCallbackParam("derived", derivedValue);
    }
}

（我不知道这是不是很好集成JSF和D3的解决方案。）

(I don't know if this is a good solution for integrating JSF and D3.)

• 使用Javascript获取支持bean值

• Getting backing bean value with Javascript

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