在 xsl:apply-templates 中使用 XSL 变量作为 Xpath 值 [英] Using an XSL variable as Xpath value in xsl:apply-templates
问题描述
我正在尝试使用节点的内容作为 Xpath 引用.不幸的是,到目前为止我还没有找到实现这一目标的方法.
I am trying to use the content of a node as an Xpath reference. Unfortunately I have not found the way to achieve this so far.
这里是我试图处理的 XML 类型的一个小例子:
So here is a little example of the type of XML I am trying to process:
<?xml version="1.0" encoding="UTF-8"?>
<root>
<a>
<b name="1">
<e>value1</e>
</b>
<b name="2">
<e>value2</e>
</b>
</a>
<c>
<d name="3">
<ref>/root/a/b[@name = "1"]</ref>
</d>
<d name="4">
<ref>/root/a/b[@name = "2"]</ref>
</d>
</c>
</root>
在那里 节点包含 Xpath 到一些包含所需值的文件内节点.
In there the <ref>
nodes contain Xpath to some in-file nodes containing the required value.
这是我试图组合在一起以处理此文件的 XSL 文件类型:
Here is the type of XSL file I was trying to put together to process this file:
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
<xsl:output method="text"/>
<xsl:template match="/">
<xsl:apply-templates select="root/c/d"/>
</xsl:template>
<xsl:template match="d">
<xsl:variable name="var1" select="ref/text()"/>
for node <xsl:value-of select="@name"/>
<xsl:apply-templates select="$var1"/>
</xsl:template>
<xsl:template match="b">
value = <xsl:value-of select="e"/>
</xsl:template>
</xsl:stylesheet>
但是当我使用建议的 XSL 处理上述 XML 文件时,我得到以下结果:
But when I process the above XML file with the proposed XSL I am getting the following result:
for node 3/root/a/b[@name = "1"]
for node 4/root/a/b[@name = "2"]
显然,$var1 的内容未被评估为有效的 xpath.
Obviously the content of $var1 is not evaluated as a valid xpath.
注意:如果我将 $var1 替换为/root/a/b[@name = "1"] 我会得到
Note: if I replace $var1 with /root/a/b[@name = "1"] I am getting
for node 3
value = value1
for node 4
value = value1
哪个更接近我想要的但节点 4 显然不再指向 value2 节点.
Which is closer to what I want but the node 4 is obviously no pointing to the value2 node anymore.
我错过了什么?
这可以用 XSL 实现吗?
Is this possible with XSL?
动态评估"是否存在问题,我是否应该使用其他方法(例如 xsl:function 或 xsl:call-template)?
Is there some problem with "dyanmic evaluation" and should I use some other mean (like xsl:function or xsl:call-template)?
感谢您的帮助.
正如Daniel Haley"所建议的那样,使用 dyn:evaluate 确实可以解决问题.
As suggested by "Daniel Haley" using dyn:evaluate does solve the problem.
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:dyn="http://exslt.org/dynamic"
version="1.0"
extension-element-prefixes="dyn">
<xsl:output method="text"/>
<xsl:template match="/">
<xsl:apply-templates select="root/c/d"/>
</xsl:template>
<xsl:template match="d"><xsl:variable name="var1" select="ref/text()"/>
for node <xsl:value-of select="@name"/>
<xsl:apply-templates select="dyn:evaluate($var1)"/>
</xsl:template>
<xsl:template match="b">
value = <xsl:value-of select="e"/>
</xsl:template>
</xsl:stylesheet>
例如将 xsltproc 与此 XSL 样式表一起使用确实会产生预期的结果.
using for example xsltproc with this XSL stylesheet does produce the expected result.
$ xsltproc ./file.xsl ./file.xml
for node 3
value = value1
for node 4
value = value2
$
我还没有研究过 xsl:evaluate 方法.
I have not investigated the xsl:evaluate method yet.
再次感谢您的帮助.
推荐答案
您可以使用 xsl:evaluate
在 XSLT 3.0 中(前提是您的处理器支持它).
You can use xsl:evaluate
in XSLT 3.0 (provided your processor supports it).
你也可以使用dyn:evaluate
EXSLT扩展功能(同样,前提是您的处理器支持).
You can also the use dyn:evaluate
EXSLT extension function (again, provided your processor supports it).
这篇关于在 xsl:apply-templates 中使用 XSL 变量作为 Xpath 值的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!