功能“ "必须在未指定默认命名空间时使用前缀 [英] The function " " must be used with a prefix when a default namespace is not specified

问题描述

我们正在对表单变量进行一些奇怪的处理。无论如何，我已经设法从请求中获取变量，所以我可以做一些数据库的东西。现在我想回发到所以选择框可以用原始选项填充。

we are doing some weird handling of our form variables. Anyway I have managed to get the variables from the request so i can do some database stuff. Now i want to post back to the from so the select boxes are can be populated with the original selections.

以下是选择字段的示例：

Here is an example of a select field:

JSP：

Condition Code: 
<select size="1" name="filterCriteria('CONDITION_CODE').values">
  <option value="">&nbsp;</option>
  <c:forEach var="bean" items="${conditions}">
    <option value="'${bean.code}'"<c:if test="${bean.code == form.filterCriteria('CONDITION_CODE').values}"> selected="selected"</c:if>>${bean.code}:&nbsp;${bean.description}</option>
  </c:forEach>
</select> 
<input type="hidden" name="filterCriteria('CONDITION_CODE').fieldName" value="CONDITION_CODE"/>
<input type="hidden" name="filterCriteria('CONDITION_CODE').operation" value="="/>

正如您所见，该名称是以下形式的函数： name = filterCriteria（'CONDITION_CODE'）。值

As you can see the name is a function in the form: name="filterCriteria('CONDITION_CODE').values

以下是表格：

private String[] fieldNames;

private Map<String, FilterCriteriaForm> filters = 
    new HashMap<String, FilterCriteriaForm>();




public String[] getFieldNames() { return this.fieldNames; }
  public Map<String, FilterCriteriaForm> getFilters() { return this.filters; }



   public FilterCriteriaForm getFilterCriteria(String fieldName)
    throws ServletException
{
    FilterCriteriaForm filter = (FilterCriteriaForm)filters.get(fieldName);

    if (filter == null)
    {
        filter = new DetFilterCriteriaForm( requestAction );
        filters.put( fieldName, filter );
    }

    return filter;
}


    public void setFilters(Map<String, FilterCriteriaForm> val) { this.filters = val; }
    }

无论如何，通常我会在jsp上执行类似这样的操作来设置字段表格中的内容：< c：if test =$ {bean.code == form.filterCriteria（'CONDITION_CODE'）。values}> selected =selected< / c：if>

Anyway normally I do something like this on the jsp to set the field back to what is in the form: "<c:if test="${bean.code == form.filterCriteria('CONDITION_CODE').values}"> selected="selected"</c:if>

当我这样做时...我收到此错误：

When I do this...I get this error:

当未指定默认命名空间时，函数filterCriteria必须与前缀一起使用

The function filterCriteria must be used with a prefix when a default namespace is not specified

编辑：

    Condition Code:&nbsp;<select size="1" name="filterCriteria('CONDITION_CODE').values">
              <c:set var="condition" value="filterCriteria('CONDITION_CODE').values" /> 
                         <option value="">&nbsp;</option>
                         <c:forEach var="bean" items="${conditions}">
                         <option value="'${bean.code}'" <c:if test="${bean.code == param[condition]}">selected="selected"</c:if>>${bean.code}:&nbsp;${bean.description}</option>
                         </c:forEach>
                         </select> 
                       <input type="hidden" name="filterCriteria('CONDITION_CODE').fieldName" value="CONDITION_CODE"/>
                       <input type="hidden" name="filterCriteria('CONDITION_CODE').operation" value="="/>
                       <br/></br>

这就是工作......我再次仔细看了一下表格......拿出来单引号并使用getFilters（）：

THIS IS WHAT WORKED....I looked at the form again closer...took out the single quotes and used the getFilters():

<select size="1" name="filterCriteria(CONDITION_CODE).values">   
             <option value="">&nbsp;</option>   
              <c:forEach var="bean" items="${conditions}">     
              <c:set var="code" value="'${bean.code}'" />     
              <option value="${code}" <c:if test='${code == form.filters["CONDITION_CODE"].values[0]}'>selected="selected"</c:if>>${bean.code}:&nbsp;${bean.description}</option>   
              </c:forEach> 
              </select> 

推荐答案

为什么要提供表单和输入元素无效的名称那样的？

Why are you giving your form and input elements invalid names like that?

无论如何，你的具体的问题是你不是要比普通字符串，而是比较EL对象。就像你现在一样，它需要一个bean $ {form} ，方法 filterCriteria（String）返回一些对象它有一个 getValues（）方法。那不是你想要的。你希望它是一个普通的字符串。

Anyway, your concrete problem is that you're not comparing to a plain string, but to an EL object. As you have now, it expects a bean ${form} with a method filterCriteria(String) which returns some object which has a getValues() method. That's not what you want. You want it to be a plain string.

修复如下，你需要引用它：

Fix it as follows, you need to quote it:

<c:if test="${bean.code == 'form.filterCriteria(\'CONDITION_CODE\').values'}"> 

但这不会让你达到功能要求。看起来你将Java / JSP与JavaScript混淆并期望它们同步运行。事实并非如此，Java / JSP在Web服务器中运行并生成HTML。 JavaScript是HTML的一部分，仅在webbrowser中运行。 表单变量仅在JavaScript中可用，而不在JSTL标记中。

But this won't let you achieve the functional requirement. It look like that you're confusing Java/JSP with JavaScript and expecting them to run in sync. This is not true, Java/JSP runs in webserver and generates HTML. JavaScript is part of HTML and runs in webbrowser only. The form variable is only available in JavaScript, not in a JSTL tag.

你实际上需要通过 $ {param} 将提交的值作为请求参数获取。所有输入元素的值都可以通过请求参数映射中的名称获得。它看起来如下：

You actually need to grab the submitted value as a request parameter by ${param}. The values of all input elements are avaiable by their name in the request parameter map. It would look like follows:

<c:if test="${bean.code == param['filterCriteria(\'CONDITION_CODE\').values']}"> 

我只是不保证是否可行，我从未使用过无效字符的名字，你也许需要对奇数字符进行URL编码。如果您根据 HTML规范。

I only don't guarantee if that would work, I have never used names with invalid characters, you perhaps need to URL-encode the odd characters. It would be much easier if you give your form and input elements a valid name which matches the rules as per HTML specification.

<select name="condition">
  <option value="">&nbsp;</option>
  <c:forEach items="${conditions}" var="condition">
    <option value="${condition.code}" ${condition.code == param.condition ? 'selected' : ''}>${condition.code}:&nbsp;${condition.description}</option>
  </c:forEach>
</select> 

（请注意，您在<选项中的值无效值> ，那些单引号不属于那里，我已将它们删除了）

(note that you had an invalid value in <option value>, those singlequotes doesn't belong there, I've removed them)

更新：根据评论，您在访问EL中的非法参数名称时似乎有EL语法错误问题。转义字符 \ 似乎被EL解析器完全吞没。你最好的选择可能是用< c：set> 代替它：

Update: as per the comments, you seem to have a EL syntax error problem when accessing the illegal parameter name in EL. The escape characters \ seems to be completely swallowed by the EL parser. Your best bet is probably to alias it with <c:set>:

<c:set var="condition" value="filterCriteria('CONDITION_CODE').values" />
...
<c:if test="${bean.code == param[condition]}"> 

---

更新2 ：那些围绕期权价值的单一报价似乎是绝对必要的。在这种情况下，您需要在其上添加另一个别名。完整代码如下所示：

---

Update 2: those singlequotes around the option value seem to be absolutely necessary. In that case, you need to add another alias on that. The full code would look like this:

<select size="1" name="filterCriteria('CONDITION_CODE').values">
  <c:set var="condition" value="filterCriteria('CONDITION_CODE').values" /> 
  <option value="">&nbsp;</option>
  <c:forEach var="bean" items="${conditions}">
    <c:set var="code" value="'${bean.code}'" />
    <option value="${code}" <c:if test="${code == param[condition]}">selected="selected"</c:if>>${bean.code}:&nbsp;${bean.description}</option>
  </c:forEach>
</select> 

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