在facelets标签的属性中定义的EL表达式内并置字符串 [英] Concatenating strings within EL expression defined in an attribute of a facelets tag

问题描述

我需要为一个属性编写一个EL表达式，其内容如下:

I need to write an EL expression for an attribute which goes something like this:

#{cc.attrs.appreciatedByCurrentUser ? (cc.attrs.count +'<br/>'+ (cc.attrs.count-1)) : ((cc.attrs.count+1) +'<br/>'+ cc.attrs.count)}

现在的问题是，由于无法连接字符串，这会产生错误，这是我的处理方式.那我该如何纠正呢?

Now the problem is that this gives an error as strings cannot be concatenated, the way I am doing it. So how can I rectify this?

我正在将JSF 2.0与facelets一起使用.

我正在使用以下嵌入式JavaScript解决问题

I'm resolving the issue using the following inline javascript

            <script type="text/javascript">
                var count=#{cc.attrs.count};
                document.write(#{cc.attrs.appreciatedByCurrentUser} ? (count-1) +'<br/>'+count  : count+'<br/>'+ (count+1));
            </script>

您能想到与此有关的任何问题吗?

Can you think of any issue with this?

推荐答案

仅通过在表达式中内联，才可以在EL中进行字符串连接. +运算符在EL中仅是和运算符.此外，<和>在XML属性中是无效字符，因此您必须对它们进行转义(并指示<h:outputText>不再通过escape="false"再次转义它们):

String concatenation in EL is only possible by just inlining in the expression. The + operator is in EL exclusively a sum operator. Further, < and > are invalid characters in XML attributes, so you have to escape them (and instruct <h:outputText> to not escape them once again by escape="false"):

<h:outputText value="#{cc.attrs.count}&lt;br/&gt;#{cc.attrs.count-1}" escape="false" rendered="#{cc.attrs.appreciatedByCurrentUser}" />
<h:outputText value="#{cc.attrs.count+1}&lt;br/&gt;#{cc.attrs.count}" escape="false" rendered="#{!cc.attrs.appreciatedByCurrentUser}" />

或者，您也可以使用<c:set>为表达式加上别名:

Alternatively, you can also use <c:set> to alias the expression:

<c:set var="appreciated" value="#{cc.attrs.count}&lt;br/&gt;#{cc.attrs.count-1}" />
<c:set var="notAppreciated" value="#{cc.attrs.count+1}&lt;br/&gt;#{cc.attrs.count}" />
<h:outputText value="#{cc.attrs.appreciatedByCurrentUser ? appreciated : notAppreciated}" escape="false" />

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