如何使用Python在XPath中以多行文本搜索内容? [英] How to search for content in XPath in multiline text using Python?

问题描述

当我使用contains在元素的text()中搜索数据的存在时，它适用于纯数据，但当元素内容中有换行符，换行符/标记时，它不起作用.在这种情况下，如何使//td[contains(text(), "")]工作?谢谢！

When I search for the existence of data in text() of an element using contains, it works for plain data but not when there are carriage returns, new lines/tags in the element content. How to make //td[contains(text(), "")] work in this case? Thank you!

XML:

<table>
  <tr>
    <td>
      Hello world <i> how are you? </i>
      Have a wonderful day.
      Good bye!
    </td>
  </tr>
  <tr>
    <td>
      Hello NJ <i>, how are you?
      Have a wonderful day.</i>
    </td>
  </tr>
</table>

Python:

>>> tdout=open('tdmultiplelines.htm', 'r')
>>> tdouthtml=lh.parse(tdout)
>>> tdout.close()
>>> tdouthtml
<lxml.etree._ElementTree object at 0x2aaae0024368>
>>> tdouthtml.xpath('//td/text()')
['\n      Hello world ', '\n      Have a wonderful day.\n      Good bye!\n    ', '\n      Hello NJ ', '\n    ']
>>> tdouthtml.xpath('//td[contains(text(),"Good bye")]')
[]  ##-> But *Good bye* is already in the `td` contents, though as a list.
>>> tdouthtml.xpath('//td[text() = "\n      Hello world "]')
[<Element td at 0x2aaae005c410>]

推荐答案

使用:

//td[text()[contains(.,'Good bye')]]

说明:

出现此问题的原因不是文本节点的字符串值是多行字符串-真正的原因是td元素具有多个文本节点子级.

The reason for the problem is not that a text node's string value is a multiline string -- the real reason is that the td element has more than one text-node children.

在提供的表达式中:

//td[contains(text(),"Good bye")]

传递给函数contains()的第一个参数是一个节点集，包含多个文本节点.

the first argument passed to the function contains() is a node-set of more than one text nodes.

根据XPath 1.0规范(在XPath 2.0中，这只会引发类型错误)，一个对函数的求值，该函数需要一个字符串参数，但会传递一个节点集，而仅采用字符串的值.节点集中的第一个节点.

As per XPath 1.0 specification (in XPath 2.0 this simply raises a type error), a the evaluation of a function that expects a string argument but is passed a node-set instead, takes the string value only of the 1st node in the node-set.

在这种情况下，传递的节点集中的第一个文本节点具有字符串值:

 "
                 Hello world "

，因此比较失败，并且未选择所需的td元素.

so the comparison fails and the wanted td element isn't selected.

基于XSLT的验证:

<xsl:stylesheet version="1.0"
 xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
 <xsl:output omit-xml-declaration="yes" indent="yes"/>

 <xsl:template match="/">
  <xsl:copy-of select="//td[text()[contains(.,'Good bye')]]"/>
 </xsl:template>
</xsl:stylesheet>

当此转换应用于提供的XML文档时:

<table>
      <tr>
        <td>
          Hello world <i> how are you? </i>
          Have a wonderful day.
          Good bye!
        </td>
      </tr>
      <tr>
        <td>
          Hello NJ <i>, how are you?
          Have a wonderful day.</i>
        </td>
      </tr>
</table>

对XPath表达式求值，并将选定的节点(在本例中为一个)复制到输出中:

<td>
          Hello world <i> how are you? </i>
          Have a wonderful day.
          Good bye!
        </td>

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