Grails< g：if> in< g：select> [英] Grails <g:if> in <g:select>

问题描述

我在 .gsp 文件中有< g：select> 。但不同于任何普通的< g：select> ，这个人会拥有属性 disabled =

以下代码：

 < / p> g：select name =test
 from =$ {[foo1，foo2]}
   

它返回一个错误： Grails标签[g：select]未关闭

但是，当我将其更改为此项时：

 < g：select name =test
 from =$ {[mu1，mu2，mu3]}
 $ {if（true）{println disabled = \\}} /> 
  

它返回了这个错误：必须引用属性值。 $ b

这两个错误消息都在异常下， org.codehaus.groovy.grails.web.taglib.exceptions.GrailsTagException

问题是我们该如何做这项工作？有没有可能的答案，而不使用自定义的TagLib？

解决方案

GSP表单字段标签treat disabled 作为一个布尔属性，所以你可以说

 < g：select .... disabled = $ {true}/> 
  

通常情况下，您应该可以在通常的Groovy-truth规则下使用任何表达式，但我相信它会使字符串true和false的特殊情况（后者在Groovy-truth规则下通常被认为是 true ，作为非空字符串）。如果有疑问，你可以总是说：
$ b $ pre $ disabled =$ {（someExpression）as boolean}





I have this <g:select> in a .gsp file. But unlike any ordinary <g:select>'s this one would have the attribute disabled="" if a certain condition is met.

Following the code:

<g:select name="test" 
          from="${["foo1","foo2"]}" 
          <g:if test="${true}">disabled=""</g:if> />

It returned an error: Grails tag [g:select] was not closed

But when I change it into this:

<g:select name="test" 
          from="${["mu1","mu2","mu3"]}" 
          ${ if(true) { println "disabled=\"\"" } }/>

It returned this error: Attribute value must be quoted.

Both of the error message are under the exception, org.codehaus.groovy.grails.web.taglib.exceptions.GrailsTagException

The question is how could we make this work? Is there a possible answer without using a custom TagLib?

解决方案

The GSP form field tags treat disabled as a boolean property, so you can say

<g:select .... disabled="${true}" />

Generally you should be able to use any expression under the usual Groovy-truth rules but I believe it makes a special case for the strings "true" and "false" (the latter would normally be considered true under Groovy-truth rules as a non-empty string). If in doubt you can always say

disabled="${(someExpression) as boolean}"

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