java 使用 JSF 2.0 在命名容器中获取组件 clientId 的完整前缀
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Acquire full prefix for a component clientId inside naming containers with JSF 2.0
提问by Tuukka Mustonen
I am updating a component via AJAX in JSF:
我正在通过 JSF 中的 AJAX 更新组件：
<h:form>
<h:outputLink>Click me
<f:ajax event="click" render=":messages" />
</h:outputLink>
</h:form>
<h:messages id="messages" globalOnly="true" />
As the <h:messages />resides outside <h:form />I have to prefix the ID with colon (:). This works.
由于<h:messages />驻留在外面，<h:form />我必须在 ID 前加上冒号 ( :)。这有效。
However, if I put this same code into a component and include that component into my page, the code fails. The reason is that :messagesdeclaration refers to the root of the component hierarchy, while the <h:messages />component that I want to update actually resides under my custom component, which resides under the page (so the location is of style :myComponent:messages.
但是，如果我将相同的代码放入一个组件并将该组件包含在我的页面中，则代码将失败。原因是:messages声明引用了组件层次结构的根，而<h:messages />我要更新的组件实际上驻留在我的自定义组件下，该组件驻留在页面下（因此位置为 style :myComponent:messages.
Inside my component, how can I achieve the correct prefix to the <h:messages />component? I know that I can manually assign ID to my component, and use that to prefix the reference (like :#{cc.attrs.id}:messages). However, I don't know at which level of component hierarchy this component lies, so the required prefix might even be something like :foo:bar:x:y:messages.
在我的组件中，如何获得<h:messages />组件的正确前缀？我知道我可以手动为我的组件分配 ID，并使用它作为引用的前缀（如:#{cc.attrs.id}:messages）。但是，我不知道该组件位于组件层次结构的哪个级别，因此所需的前缀甚至可能类似于:foo:bar:x:y:messages.
回答by Tuukka Mustonen
Seems like you can access the current prefix via Expression Language (EL) implicit objects (ccand component):
似乎您可以通过表达式语言 (EL) 隐式对象 (cc和component)访问当前前缀：
cc.clientIdreturns current compositecomponent's prefixcomponent.clientIdreturns prefix for any current component.
cc.clientId返回当前复合组件的前缀component.clientId返回任何当前组件的前缀。
For example, in a page, call some component via
例如，在一个页面中，通过调用某个组件
<myComponent id="foo">
Inside this component, one can fetch the client IDs like this:
在这个组件中，可以像这样获取客户端 ID：
<h:outputText id="bar">
<p>ClientId for the composite component: #{cc.clientId}</p>
<p>ClientId for current any component: #{component.clientId}</p>
</h:outputText>
The following should print out as:
以下应打印为：
ClientId for the composite component: foo
ClientId for current any component: foo:bar
I got the pointer from blog post JSF: working with component identifiers (id/clientId). It states that this is a new feature for JSF 2.0. Before that one had to fetch the ID programmatically from a backing bean.
我从博客文章JSF: working with component identifiers (id/clientId) 中得到了指针。它声明这是 JSF 2.0 的一个新特性。在此之前，必须以编程方式从支持 bean 中获取 ID。
回答by Ziletka
@Tuukka Mustonen, thank you for your answer.
@Tuukka Mustonen，感谢您的回答。
And if we need access some another id from the same "place" we could use:
如果我们需要从同一个“地方”访问另一个 id，我们可以使用：
<h:outputScript name="js/my-script.js"/>
<h:form id="myForm">
<h:inputText id="aaa"
onkeyup="myJSFunction(this.id)"
value="..."
/>
<h:inputText id="bbb"
onkeyup="myJSFunction(aaa.id)"
value="..."
/>
<h:inputText id="ccc"
onkeyup="myJSFunction('#component.parent.clientId.concat(':ccc')}')"
value="..."
/>
<h:inputText id="ddd"
onkeyup="myJSFunction('#component.parent.clientId.concat(':aaa')}')"
value="..."
/>
</h:form>
JavaScript function:
JavaScript 函数：
function myJSFunction(message) {
window.alert(message)
}
Output on dialog window:
对话窗口输出：
1) myForm:aaa
1）我的表格：aaa
2) null
2)空
3) myForm:ccc
3) myForm:ccc
4) myForm:aaa
4）我的表格：aaa
Note: so the 1st and 3th have the same output.
注意：所以第 1 个和第 3 个具有相同的输出。
