p:selectOneMenu在存在noSelectionOption项目时预选择上一个项目 [英] p:selectOneMenu preselects previous item when noSelectionOption item is present

问题描述

添加f:selectItem时p:selectOneMenu选择存在问题.

查看:

<p:selectOneMenu value="#{selectionTest.selectedName}">
    <f:selectItem itemLabel="Select" noSelectionOption="true" />
    <f:selectItems value="#{selectionTest.allNames}" var="varName" itemLabel="#{varName}" itemValue="#{varName}" />
</p:selectOneMenu>

型号:

private List<String> allNames;
private String selectedName;

public MenuSelectionTestBean(){
    allNames = new ArrayList<String>();
    allNames.add("Ahmed");
    allNames.add("Mohamed");
    allNames.add("Ibrahim");
    allNames.add("Walid");

    selectedName ="Walid";
}

结果:

应选择"Walid"项目，但应选择"Ibrahim".我认为PrimeFaces会根据列表中的索引而不是项目的值来选择该项目.

The item "Walid" should be selected, however "Ibrahim" is selected instead. I think that PrimeFaces selects the item depending on its index in the list and not the value of the item.

这是怎么引起的，我该如何解决?

How is this caused and how can I solve it?

推荐答案

我可以重现您的问题.我查看了PrimeFaces源代码.这是PrimeFaces SelectOneMenuRenderer中的一个错误，该错误仅在使用带有noSelectionOption="true"的项目时才公开.渲染器不会为此生成背景<select>元素的HTML <option>元素，但会为此生成可视<ul>列表的<li>.换句话说，在您的情况下，<select>包含4个项目，而<ul>包含5个项目. JavaScript会根据您怀疑的<option selected>索引选择<li>.那解释了你的问题.

I could reproduce your problem. I looked in the PrimeFaces source code. It's a bug in PrimeFaces SelectOneMenuRenderer which exposes only when an item with noSelectionOption="true" is been used. The renderer won't generate the HTML <option> element of the backing <select> element for that, but it will generate the <li> of the visual <ul> list for that. In other words, the <select> contains in your case 4 items and the <ul> 5 items. The <li> is selected by JavaScript based on the index of the <option selected>, exactly as you suspected. That explains your problem.

您最好的选择是将其报告为错误给PrimeFaces家伙.渲染器还应该为此生成<option>，或者JavaScript应该基于值而不是基于索引选择选项.

Your best bet is to report it as a bug to PrimeFaces guys. The renderer should also generate the <option> for that, or the JavaScript should select the option based on value instead of on index.

同时，将JSF配置为将空字符串提交的值解释为null时，用itemValue="#{null}"替换noSelectionOption="true"，或者用itemValue=""替换itemValue=""应该可以解决您的问题.

In the meanwhile, replacing the noSelectionOption="true" by itemValue="#{null}", or also itemValue="" when JSF is configured to interpret empty string submitted values as null, should solve your problem.

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