尽管 render=“false”，但 ah:dataTable 的内容始终会被评估

发布于 2024-10-13 08:10:28 字数 699 浏览 5 评论 0原文

我的 JSF 2.0 的 HtmlDataTable 有问题。在我的网页上，我有 ah:dataTable 和一些其他内容，只有在用户登录时才应呈现这些内容。

HtmlDataTable 的内容是从数据库加载的。尽管当用户未登录时不会呈现 h:dataTable，但仍会评估内容。

这是网页的代码：

<h:panelGroup rendered="#{userBean.loggedIn}">
    <h:dataTable value="#{xxxBean.allXxx}"
                 var="c">
        <h:column>
            <h:outputText value="#{c.name}"/>
        </h:column>
    </h:dataTable>
    <!-- some other content -->
</h:panelGroup>

在 getAllXxx() 方法中，我正在记录该方法的调用。但如果 h:dataTable（以及所有其他内容）未呈现，则仍会调用 getAllXxx() 方法。

我尝试使用 c:if 而不是 h:panelGroup。这可行，但是我在登录过程中遇到问题，所以这不是合适的解决方案。

有谁知道如何解决这个问题？提前致谢。

原文

I have got a problem with the HtmlDataTable of JSF 2.0. On my web page, i have got a h:dataTable and some other content, which should only be rendered if the user is logged in.

The content of the HtmlDataTable is loaded from a database. Although the h:dataTable is not rendered when the user is not logged in, the content is still evaluated.

Here is the code of the web page:

<h:panelGroup rendered="#{userBean.loggedIn}">
    <h:dataTable value="#{xxxBean.allXxx}"
                 var="c">
        <h:column>
            <h:outputText value="#{c.name}"/>
        </h:column>
    </h:dataTable>
    <!-- some other content -->
</h:panelGroup>

In the getAllXxx() method I am logging the call of the method. But also if the h:dataTable (and all the other content) is not rendered, the getAllXxx() method is still called.

I tried to use c:if instead of the h:panelGroup. That would work, but then I get issues during the login-process, so this is no suitable solution.

Does anyone know how to fix this? Thanks in advance.

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勿忘初心 2024-10-20 08:10:28

使用以下 SSCCE 无法在 Tomcat 7.0.5 上的 Mojarra 2.0.3 上重现您的问题。

test.xhtml

<!DOCTYPE html>
<html lang="en"
    xmlns="http://www.w3.org/1999/xhtml"
    xmlns:h="http://java.sun.com/jsf/html">
    <h:head>
        <title>SO question 4774516</title>
    </h:head>
    <h:body>
        <h:panelGroup rendered="#{param.show}">
            <h:dataTable value="#{bean.list}" var="item">
                <h:column>#{item}</h:column>
            </h:dataTable>
        </h:panelGroup>
    </h:body>  
</html>

com.example.Bean

package com.example;

import java.util.Arrays;
import java.util.List;

import javax.faces.bean.ManagedBean;
import javax.faces.bean.RequestScoped;

@ManagedBean
@RequestScoped
public class Bean {

    private List<String> list = Arrays.asList("one", "two", "three");

    public List<String> getList() {
        System.out.println("getList() called");
        return list;
    }

}

打开http: //localhost:8080/playground/test.jsf 不显示任何标准输出行。打开 http://localhost:8080/playground/test.jsf?show=true 向他们展示。

你的问题是由其他原因引起的。这要么是 JSF 实现中的错误，要么是您误解了该过程。例如，它实际上可以是一个回发请求，其中 getter 在应用请求值阶段被调用，而 #{userBean.loggedIn} 的结果仅在调用操作期间更改阶段。或者 getter 被其他东西调用。

Can't reproduce your problem on Mojarra 2.0.3 on Tomcat 7.0.5 with the following SSCCE.

test.xhtml

<!DOCTYPE html>
<html lang="en"
    xmlns="http://www.w3.org/1999/xhtml"
    xmlns:h="http://java.sun.com/jsf/html">
    <h:head>
        <title>SO question 4774516</title>
    </h:head>
    <h:body>
        <h:panelGroup rendered="#{param.show}">
            <h:dataTable value="#{bean.list}" var="item">
                <h:column>#{item}</h:column>
            </h:dataTable>
        </h:panelGroup>
    </h:body>  
</html>

com.example.Bean

package com.example;

import java.util.Arrays;
import java.util.List;

import javax.faces.bean.ManagedBean;
import javax.faces.bean.RequestScoped;

@ManagedBean
@RequestScoped
public class Bean {

    private List<String> list = Arrays.asList("one", "two", "three");

    public List<String> getList() {
        System.out.println("getList() called");
        return list;
    }

}

Opening http://localhost:8080/playground/test.jsf doesn't show any stdout lines. Opening http://localhost:8080/playground/test.jsf?show=true shows them.

Your problem is caused by something else. Either it's a bug in your JSF implementation or you just misinterpreted the procedure. It can for example actually be a postback request wherein the getter is been called during apply request values phase and the outcome of #{userBean.loggedIn} is only changed during invoke action phase. Or the getter is called by something else.

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