dom - find redirect META in DOMDocument with DOMXPath

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dom - find redirect META in DOMDocument with DOMXPath

posted Jan 31, 2022 in Technique[技术] by 深蓝 (71.8m points)

dom - find redirect META in DOMDocument with DOMXPath

I have the following HTML:

<html>
    <head>
        <meta http-equiv="refresh" content="0;URL=http://amazingjokes.com" />
    </head>
</html>

I want to find the META with the redirect, so I wrote the following XPath query:

/html/head/meta[@http-equiv="refresh"]

However, the '-' in 'http-equiv' is causing an error:

Invalid regular expression: //html/head/meta[@http-equiv="refresh"]/: Range out of order in character class

How can I properly rewrite the xpath query to be able to find the meta redirect?

I experimented with this, when I remove the '-' from the HTML code and the query things work as expected, but unfortunately the 'http-equiv' is a set standard, so I can not change that. This experiment showed me I am very close...

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1 Reply

深蓝 · Answer 1 · 2022-01-31T07:05:56+0000

However, the '-' in 'http-equiv' is causing an error:

Invalid regular expression: //html/head/meta[@http-equiv="refresh"]/: Range out of order in character class

Obviously, the XPath engine you are using is buggy.

The XPath expression used in the question is a valid XPath 1.0 expression and it selects the wanted <meta> element.

Here is an XSLT - based verification:

<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="/html/head/meta[@http-equiv='refresh']"/>
  </xsl:template>
</xsl:stylesheet>

When the transformation above is applied on the provided XML document:

<html>
    <head>
        <meta http-equiv="refresh" content="0;URL=http://amazingjokes.com" />
    </head>
</html>

the XPath expression is evaluated and the selected in this evaluation node is output:

<meta http-equiv="refresh" content="0;URL=http://amazingjokes.com"/>

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dom - find redirect META in DOMDocument with DOMXPath

dom - find redirect META in DOMDocument with DOMXPath

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