XHTML namespace issues with cssselect in lxml

问题

I have problems using cssselect with a XHTML (or XML with namespace). Although the documentation says how to use namespace in csselect I do not understand it: cssselect namespaces

My Input XHTML string:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
  <title>Teststylesheet</title>
  <style type="text/css">
  /*<![CDATA[*/
  ol{margin:0;padding:0}
  /*]]>*/
  </style>
</head>
<body>
</body>
</html>

My Python Script:

parser = etree.XMLParser()    
tree = etree.fromstring(xhtmlstring, parser).getroottree()
for style in CSSSelector("style")(tree):
  print "HAVE CSS!"

The python script does not print any Have CSS!. Using the etree.HTMLParser instead of etree.XMLParser works but I really want to use the XMLParser and keep everything (namespace, structure) of the XHTML.

Can anybody help me with this namespace problem?

回答1:

The doc string for cssselect.CSSSelector (version 2.0) shows how to use namespaces:

class CSSSelector(etree.XPath):
    """ ...
    To use CSS namespaces, you need to pass a prefix-to-namespace
    mapping as ``namespaces`` keyword argument::

        >>> rdfns = 'http://www.w3.org/1999/02/22-rdf-syntax-ns#'
        >>> select_ns = cssselect.CSSSelector('root > rdf|Description',
        ...                                   namespaces={'rdf': rdfns})

        >>> rdf = etree.XML((
        ...     '<root xmlns:rdf="%s">'
        ...       '<rdf:Description>blah</rdf:Description>'
        ...     '</root>') % rdfns)
        >>> [(el.tag, el.text) for el in select_ns(rdf)]
        [('{http://www.w3.org/1999/02/22-rdf-syntax-ns#}Description', 'blah')]
    """

If you've tried this but your version of cssselect.CSSSelector does not have a namespaces parameter, then your version of lxml may need to be upgraded.

来源：https://stackoverflow.com/questions/6860013/xhtml-namespace-issues-with-cssselect-in-lxml

标签

python

css

xhtml

lxml

xml-namespaces