JSTL c:选择c:不在JSF页面中工作 [英] JSTL c:choose c:when not working in a JSF page
问题描述
请考虑以下 jstl 选择:
Consider the following jstl choose:
<c:choose>
<c:when test="#{AuthMsgBean.rw['2'] ne null}">
Display Text
</c:when>
<c:otherwise>
<ph:outputText id="pan" value="Component pan could not be created." />
</c:otherwise>
</c:choose>
AuthMsgBean = Bean
rw =地图
'2'=关键
问题:
当我只显示#{AuthMsgBean.rw ['2'] ne null}
值时,它显示正常(true),但是一旦我尝试将值解析为< c:when test =/>
when标签重新起作用,好像测试始终为假。
When I simply display the #{AuthMsgBean.rw['2'] ne null}
value it displays fine (true), but once I try to parse the value to the <c:when test=""/>
the when tag re-acts as if the test is always false.
如果我在测试中输入了真( test =true
),则显示显示文本。
If I put true in the test (test="true"
) the Display Text is displayed.
可能是< c:when>
标记在之前评估#{AuthMsgBean.rw ['2'] ne null }
表达式?
如果有,是否有解决方法?
If so, is there a workaround?
推荐答案
JSTL和JSF不会像编码时那样同步运行。在JSF视图构建时,它是JSTL,它首先从上到下运行,以生成仅包含JSF标记的视图。在JSF视图渲染时,JSF从上到下再次运行以产生一堆HTML。
JSTL and JSF do not run in sync as you'd expect from coding. During JSF view build time, it's JSTL which runs from top to bottom first to produce a view with only JSF tags. During JSF view render time, it's JSF which runs from top to bottom again to produce a bunch of HTML.
显然#{AuthMsgBean} <当JSTL轮到运行时,范围内不存在/ code>。当标记放在JSF迭代组件中时可能会发生这种情况,例如
< h:dataTable>
。
无论如何,你不想在这里使用JSTL。使用JSF 渲染
attribtue。
Regardless, you do not want to use JSTL here. Make use of the JSF rendered
attribtue.
<h:panelGroup rendered="#{not empty AuthMsgBean.rw['2']}">
Display Text
</h:panelGroup>
<h:outputText id="pan" value="Component pan could not be created." rendered="#{empty AuthMsgBean.rw['2']}" />
参见:
- 有条件地展示JSF组件
- Conditionally displaying JSF components
See also:
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