XPath and XQuery in Python?

**John Lenton** · Jul 18 '05, 08:15 PM

Re: XPath and XQuery in Python?

On Wed, Jan 12, 2005 at 12:09:58AM +0000, Nelson Minar wrote:[color=blue]
> Could someone help me get started using XPath or XQuery in Python? I'm
> overwhelmed by all the various options and am lacking guidance on what
> the simplest way to go is. What library do I need to enable three line
> Python programs to extract data with XPath expressions?
>
> I have this problem a lot with Python and XML. Even with Uche's
> excellent yearly roundups I have a hard time finding how to do fancy
> things with XML in Python. I think it's a bit like web server
> frameworks in Python - too many choices.[/color]

my own favorite is libxml2. Something like the following:

#!/usr/bin/env python
import libxml2
import sys

def grep(what, where):
doc = libxml2.parseDo c(where)
for found in doc.xpathEval(w hat):
found.saveTo(sy s.stdout, format=True)

if __name__ == '__main__':
try:
what = sys.argv[1]
except IndexError:
sys.exit("Usage : %s pattern file ..." % sys.argv[0])
else:
for where in sys.argv[2:]:
grep(what, file(where).rea d())

although you might want to be smarter with the errors...

--
John Lenton (john@grulic.or g.ar) -- Random fortune:
The whole world is a scab. The point is to pick it constructively.
-- Peter Beard

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**Nelson Minar** · Jul 18 '05, 08:17 PM

Re: XPath and XQuery in Python?

Nelson Minar <nelson@monkey. org> writes:[color=blue]
> Could someone help me get started using XPath or XQuery in Python?[/color]

I figured this out. Thanks for the help, John! Examples below.

I used this exercise as an opportunity to get something off my chest
about XML and Python - it's kind of a mess! More here:

http://www.nelson.monkey.org/~nelson/weblog/tech/python/xpath.html

Here are my samples, in three libraries:

# PyXML

from xml.dom.ext.rea der import Sax2
from xml import xpath
doc = Sax2.FromXmlFil e('foo.opml').d ocumentElement
for url in xpath.Evaluate( '//@xmlUrl', doc):
print url.value

# libxml2

import libxml2
doc = libxml2.parseFi le('foo.opml')
for url in doc.xpathEval('//@xmlUrl'):
print url.content

# ElementTree

from elementtree import ElementTree
tree = ElementTree.par se("foo.opml")
for outline in tree.findall("//outline"):
print outline.get('xm lUrl')

Please see my blog entry for more commentary

http://www.nelson.monkey.org/~nelson/weblog/tech/python/xpath.html

**Uche Ogbuji** · Jul 18 '05, 08:18 PM

Re: XPath and XQuery in Python?

Interesting discussion. My own thoughts:

http://www.oreillynet.com/pub/wlg/6224
http://www.oreillynet.com/pub/wlg/6225

Meanwhile, please don't make the mistake of bothering with XQuery.
It's despicable crap. And a huge impedance mismatch with Python.
--Uche

XPath and XQuery in Python?

XPath and XQuery in Python?

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