当我使用contains搜索元素的text()中数据的存在时,它适用于普通数据,但是当元素内容中有回车符,新行/标记时则不行.如何使// td [contains(text(),“”)]在这种情况下工作?谢谢!
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>]
解决方法:
使用:
//td[text()[contains(.,'Good bye')]]
说明:
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元素有多个文本节点子节点.
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包含多个文本节点的节点集.
根据XPath 1.0规范(在XPath 2.0中,这只会引发类型错误),对需要字符串参数但是传递给节点集的函数的求值,只获取节点中第1个节点的字符串值 – 组.
在这种特定情况下,传递的节点集的第一个文本节点具有字符串值:
"
Hello world "
所以比较失败并且没有选择想要的td元素.
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>
在提供的XML文档上应用此转换时:
<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>
评估XPath表达式,并将选定的节点(在本例中只是一个)复制到输出:
<td>
Hello world <i> how are you? </i>
Have a wonderful day.
Good bye!
</td>