关于 XSLT 文件的 XPATH 和 XSLT If 语句的问题 [英] Question on XPATH for an XSLT File And XSLT If Statement

问题描述

我有以下 xml 文件

I have the following xml file

<DriveLayout>
<Drive driveVolume="/u" Group="sa" Owner="sa" totalSpace="4" />
<Drive driveVolume="/u" Group="sa" Owner="sa" totalSpace="16" />
<Drive driveVolume="/u" Group="sa" Owner="sa" totalSpace="510" />
<Drive driveVolume="/u" Group="sa" Owner="sa" />
<Drive driveVolume="/u" Group="sa" Owner="sa" totalSpace="15" />
<VolumeGroups>
<VolumeGroup storage="1" />
<VolumeGroup totalSpace="32" />
<VolumeGroup totalSpace="16" />
</VolumeGroups>
</DriveLayout>

我正在尝试使用类似这样的 xslt 样式表来访问它.

I'm trying to access it using an xslt stylesheet which looks something like this.

    <td class="LabelText" Width="10%">
      <xsl:value-of select="/DriveLayout/VolumeGroups/@totalSpace" />
    </td>

这似乎不正确有人知道正确的 XPATH 是什么吗?

This doesn't seem to be correct does anyone know what the correct XPATH would be?

另外，我想使用一个 xslt if 语句来查看字段 totalSpace 是否存在于 Drive 节点中.我尝试使用下面这样的东西，但没有成功.

Also, I want to use an xslt if statement to see if the field totalSpace exists in the Drive node. I tried using something like this below but this was unsuccessful.

<xsl:if test="@totalSpace = ''" >

感谢您的帮助.

推荐答案

您需要编写完整路径才能使其工作.处理器怎么会知道你指的是什么.

You need to write full paths to make it work. How else would the processor know what you refer to.

与您目前所拥有的相比，最小的变化是:

The minimum changes from what you currently have would be this:

<td class="LabelText" Width="10%">
  <xsl:value-of select="/DriveLayout/VolumeGroups/VolumeGroup/@totalSpace[1]" />
</td>  <!-- you need to write full paths! -------^^^^^^^^^^^^ -->

还有这个:

<td class="LabelText" Width="10%">
  <xsl:value-of select="/DriveLayout/VolumeGroups/VolumeGroup/@totalSpace[2]" />
</td>

还有这个:

<xsl:if test="/DriveLayout/Drive/@totalSpace">
  <!-- ... -->
</xsl:if>

一个节点的存在可以简单地通过为它编写一个 XPath 表达式来检查.如果不存在，则结果节点集将为空，空节点集评估为假.

The existence of a node can be checked simply by writing an XPath expression for it. If does not exist, the resulting node-set will be empty, and empty node-sets evaluate to false.

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