如何使用XPath选择子节点#text节点值最长的XML节点? [英] How do I select an XML node with the longest child #text node value with XPath?

问题描述

在使用此查询之前，我已经使用XPath选择了具有最大整数id值的节点:

I've used XPath to select the node with the largest integer id value before using this query:

//somenode[not(@id <= preceding::somenode/@id) and not(@id <= following::somenode/@id)]

我希望可以做类似的事情:

I was hoping that I could do something similar like:

//entry[not(string-length(child::text()) <= string-length(preceding::entry/child::text())) and not(string-length(child::text()) <= string-length(following::entry/child::text()))]

但是它返回一堆节点，而不是一个.

But it returns a bunch of nodes instead of just one.

示例XML:

<xml>
  <entry>Lorem ipsum dolor sit amet, consectetur adipiscing elit.</entry>
  <entry>Nam dignissim mi a massa mattis rutrum eu eget mauris.</entry>
  <entry>Ut at diam a sem scelerisque pretium nec pulvinar purus.</entry>
  <entry>Nunc in nisi nec dolor accumsan suscipit vel a quam.</entry>
  <entry>Nunc suscipit lobortis arcu, nec adipiscing libero bibendum nec.</entry>
  <entry>Aenean eget ipsum et nunc eleifend scelerisque.</entry>
  <entry>In eu magna et diam volutpat molestie.</entry>
  <entry>In volutpat luctus mi, eu laoreet orci dictum vel.</entry>
  <entry>In mattis mi nec magna sodales eu bibendum felis aliquet.</entry>
<!-- etc for 800 more lines or so -->
  <entry>Duis auctor felis id neque gravida ut auctor ipsum ullamcorper.</entry>
  <entry>Sed vel tortor mauris, et aliquet tellus.</entry>
</xml>

XPath测试: http://chris.photobooks.com/xml/default .htm?state = 1o

推荐答案

无法使用单个XPath 1.0表达式选择所需元素，因为在XPath 1.0中无法应用对所有选定节点的功能(string-length(someNodeSet)仅应用于此节点集的第一个节点).另一个原因是，在XPath 1.0中，无法命名和引用范围变量.

The wanted element(s) cannot be selected with a single XPath 1.0 expression, because in XPath 1.0 it is not possible to apply a function to all selected nodes (string-length(someNodeSet) is applied only on the first node of this node-set). Another reason is that in XPath 1.0 it isn't possible to name and reference range variables.

在XPath 2.0中，这很简单:

/*/entry[not(string-length(.) < /*/entry/string-length(.))]

上面选择了所有entry个元素，这些元素的字符串值最大.

The above selects all entry elements the length of whose string value is the maximal one.

/*/entry[not(string-length(.) < /*/entry/string-length(.))] [1]

上面选择了第一个(按文档顺序)诸如entry元素.

The above selects the first (in document order) such entry element.

基于XSLT 2.0的验证:

此转换:

<xsl:stylesheet version="2.0"
    xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

 <xsl:template match="/">
  <xsl:sequence select=
   "/*/entry[not(string-length(.) &lt; /*/entry/string-length(.))]"/>
 </xsl:template>
</xsl:stylesheet>

应用于提供的XML文档:

<xml>
  <entry>Lorem ipsum dolor sit amet, consectetur adipiscing elit.</entry>
  <entry>Nam dignissim mi a massa mattis rutrum eu eget mauris.</entry>
  <entry>Ut at diam a sem scelerisque pretium nec pulvinar purus.</entry>
  <entry>Nunc in nisi nec dolor accumsan suscipit vel a quam.</entry>
  <entry>Nunc suscipit lobortis arcu, nec adipiscing libero bibendum nec.</entry>
  <entry>Aenean eget ipsum et nunc eleifend scelerisque.</entry>
  <entry>In eu magna et diam volutpat molestie.</entry>
  <entry>In volutpat luctus mi, eu laoreet orci dictum vel.</entry>
  <entry>In mattis mi nec magna sodales eu bibendum felis aliquet.</entry>
<!-- etc for 800 more lines or so -->
  <entry>Duis auctor felis id neque gravida ut auctor ipsum ullamcorper.</entry>
  <entry>Sed vel tortor mauris, et aliquet tellus.</entry>
</xml>

选择具有最大字符串长度的entry元素(在这种情况下，只有一个)并输出所选元素:

selects the entry elements (in this case only one) with the maximum string-length and outputs the selected elements:

<entry>Nunc suscipit lobortis arcu, nec adipiscing libero bibendum nec.</entry>

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