日期正在打印，但未能在jstl中评估为空 [英] Date is printing but failed to evaluate as not empty in jstl

问题描述

我使用JSTL在我的JSP中迭代Spring模型值。
我使用JSTL在JSP中显示两个日期。

以下是我的Java代码：

  model.put（oldest，timesheetService.getOldestPendingTimesheet（userDetails））; 
 model.put（pending，timesheetService.getNextOldestPendingTimesheet（userDetails））; 
  

JSP代码：

 < c：选择> 
< c：when test =$ {not empty model.oldest}> 
< c：out value =$ {model.oldest}/> 
< / c：当> 
 < c：out value =$ {model.pending}/> 
< / c：当> 
   

我在之外显示两个日期c：choose 它打印如下

 最早：Tue Nov 04 00:00:00 IST 2014 
待定：太阳Nov 09 00:00:00 IST 2014 
  

最旧日期打印在 c：当时，但挂起仅在 c：选择之外打印，并且不打印在 c中：。

上面的代码有什么问题？

解决方案

这是因为当< c：choose> 中有多个< c：when> 时，第一个被解释为，如果，其他所有其他的被解释为 else if 。所以，你的第一个条件是满足的，当被忽略时，第二个

如果你想要打印它们两个取决于非排他性条件，最好使用< c：if> 。

<$ p $，比< c：choose> 构造更容易阅读。

p> < c：if test =$ {not empty model.oldest}>
< c：out value =$ {model.oldest}/>
< / c：if>
< c：out value =$ {model.pending}/>
< / c：if>


I am using JSTL to iterate Spring model values in my JSP. I display the two dates in my JSP using JSTL.

Below is my Java code:

model.put("oldest",timesheetService.getOldestPendingTimesheet(userDetails));
model.put("pending", timesheetService.getNextOldestPendingTimesheet(userDetails));

JSP Code:

<c:choose>
    <c:when test="${not empty model.oldest}">
        <c:out value="${model.oldest}"/>
    </c:when>
    <c:when test="${not empty model.pending}">
        <c:out value="${model.pending}"/>
    </c:when>       
</c:choose>

I display the both dates in outside the c:choose it printing like below

oldest:Tue Nov 04 00:00:00 IST 2014 
Pending:Sun Nov 09 00:00:00 IST 2014

Oldest Date is printing inside the c:when, but pending is printing only outside the c:choose and not printing inside the c:when.

What's wrong with the above code?

解决方案

That's because when you have several <c:when> in <c:choose>, the first one is interpreted as if and all the others as else if. So, your first condition is satisfied and the second when is ignored.

If you want to print both of them depending on non-exclusive conditions, better use <c:if>. It is also easier to read than <c:choose> construct, when you have few conditions.

<c:if test="${not empty model.oldest}">
    <c:out value="${model.oldest}"/>
</c:if>
<c:if test="${not empty model.pending}">
    <c:out value="${model.pending}"/>
</c:if>

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