指定? 内元素的条件渲染似乎不起作用
我正在尝试使用
我尝试在 false。
<ul>
<ui:repeat value="#{topics.list}" var="topicId" >
<li>#{topicId}</li>
<c:if test="#{topicId eq -1}"> <br/> </c:if>
</ui:repeat>
</ul>
这可能吗？
I am trying to conditionally build a custom list using <ui:repeat>. On every occurrence of -1 as item-value in list, I need to add a line break.
I tried to use <c:if> inside <ui:repeat> for that, but it does not seem to work. It always evaluates false.
<ul>
<ui:repeat value="#{topics.list}" var="topicId" >
<li>#{topicId}</li>
<c:if test="#{topicId eq -1}"> <br/> </c:if>
</ui:repeat>
</ul>
Is this possible?
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没有 JSTL 标签，不行。它们在视图构建期间运行，而不是在视图渲染期间运行。您可以将其形象化如下：当 JSF 构建视图时，JSTL 标记首先从上到下运行，结果是一个纯 JSF 组件树。然后，当 JSF 渲染视图时，JSF 组件从上到下运行，结果是一堆 HTML。因此，JSTL 和 JSF 并不像您期望的编码那样同步运行。当您的JSF 组件在范围内不可用。
#{topicId}变量由您需要在感兴趣的 JSF 组件的
rendered属性中指定条件，而不是使用替代方案是
或根据您的具体情况
因为当未指定客户端属性时，两者也不向 HTML 输出发出任何其他内容。
另请参阅：
与具体问题无关，这是
的错误位置。任何遵守 HTML 规范的网络浏览器都会忽略它。您不是说它在
内部吗？或者更好的是，给它一个class并让 CSS 给它一个margin-bottom。Not with JSTL tags, no. They run during view build time, not during view render time. You can visualize it as follows: when JSF builds the view, JSTL tags run from top to bottom first and the result is a pure JSF component tree. Then when JSF renders the view, JSF components run from top to bottom and the result is a bunch of HTML. So, JSTL and JSF don't run in sync as you'd expect from the coding. At the moment your
<c:if>JSTL tag tag runs, the#{topicId}variable which is set by<ui:repeat>JSF component isn't available in the scope.Instead of using
<c:if>, you need to specify the condition in therenderedattribute of the JSF component of interest. As you've actually none, you could wrap it in a<ui:fragment>.Alternatives are
<h:panelGroup>or in your specific case
<h:outputText escape="false">as both also emits nothing else to the HTML output when no client side attributes are specified.
See also:
Unrelated to the concrete problem, that's the wrong place for a
<br/>. It would be ignored by any webbrowser respecting the HTML specification. Don't you mean it to be inside the<li>? Or better, give it aclassand let CSS give it amargin-bottom.