尝试将XML从字符串解析为Python

Question

So first the string

'<?xml version="1.0" encoding="UTF-8"?><metalink version="3.0" xmlns="http://www.metalinker.org/" xmlns:lcgdm="LCGDM:" generator="lcgdm-dav" pubdate="Fri, 11 Oct 2013 12:46:10 GMT"><files><file name="/lhcb/L"><size>173272912</size><resources><url type="https">https://test-kit.test.de:2880/pnfs/test.file</url><url type="https">https://test.grid.sara.nl:2882/pnfs/test.file</url></resources></file></files></metalink>'

What I want to extract is the url text. Following code works but has flaws because it's hard coded:

root = ET.fromstring( xml_string )
for entry in root[0][0][1].iter():
  print entry.text

So this only works if the xml structure is the same. I tried to use xpath but I never got it working or with tags. I never got any results.

Is it a problem with the format of the xml string or am I doing something wrong?

Answer 1

You can use xpath (and findall function of Node ) to get the urls , but since you have used xmlns="http://www.metalinker.org/" for the root element, you will need to use that xmlns in the xpath as well.

Example -

>>> root = fromstring(xml_string)
>>> urls = root.findall('.//{http://www.metalinker.org/}url')
>>> for url in urls:
...     print(url.text)
...
https://test-kit.test.de:2880/pnfs/test.file
https://test.grid.sara.nl:2882/pnfs/test.file

The above xpath will find all urls in the xml.

Answer 2

You used namespaces, so you need to use them in XPath:

for entry in root.findall('.//{http://www.metalinker.org/}url'):
    print entry.text