XML parsing specific values - Python

Question

I've been attempting to parse a list of xml files. I'd like to print specific values such as the userName value.

<?xml version="1.0" encoding="utf-8"?>
<Drives clsid="{8FDDCC1A-0C3C-43cd-A6B4-71A6DF20DA8C}" 
        disabled="1">
  <Drive clsid="{935D1B74-9CB8-4e3c-9914-7DD559B7A417}" 
         name="S:" 
         status="S:" 
         image="2" 
         changed="2007-07-06 20:57:37" 
         uid="{4DA4A7E3-F1D8-4FB1-874F-D2F7D16F7065}">
    <Properties action="U" 
                thisDrive="NOCHANGE" 
                allDrives="NOCHANGE" 
                userName="" 
                cpassword="" 
                path="\\scratch" 
                label="SCRATCH" 
                persistent="1" 
                useLetter="1" 
                letter="S"/>
  </Drive>
</Drives>

My script is working fine collecting a list of xml files etc. However the below function is to print the relevant values. I'm trying to achieve this as suggested in this post. However I'm clearly doing something incorrectly as I'm getting errors suggesting that elm object has no attribute text. Any help would be appreciated.

Current Code

from lxml import etree as ET

def read_files(files):
    for fi in files:
        doc = ET.parse(fi)
        elm = doc.find('userName')
        print elm.text

Dan Lenski · Accepted Answer · 2014-09-09 19:39:55Z

1

doc.find looks for a tag with the given name. You are looking for an attribute with the given name.

elm.text is giving you an error because doc.find doesn't find any tags, so it returns None, which has no text property.

Read the lxml.etree docs some more, and then try something like this:

doc = ET.parse(fi)
root = doc.getroot()
prop = root.find(".//Properties") # finds the first <Properties> tag anywhere
elm = prop.attrib['userName']

answered Sep 9, 2014 at 19:39

Dan Lenski

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2 Comments

Charles Duffy Over a year ago

Eh? It's not the root that the attribute hangs off of.

Dan Lenski Over a year ago

You're quite right, I fixed my answer to look for the attribute of the Properties tag instead.

Charles Duffy · Accepted Answer · 2014-09-09 19:39:53Z

1

userName is an attribute, not an element. Attributes don't have text nodes attached to them at all.

for el in doc.xpath('//*[@userName]'):
  print el.attrib['userName']

answered Sep 9, 2014 at 19:39

Charles Duffy

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6 Comments

iNoob Over a year ago

could you please explain the //*[@userName] value? Id like to understand how to add multiple attributes.

Dan Lenski Over a year ago

@iNoob, you should read the etree docs for how to use an XPath-like specification to find tags with specific attributes: docs.python.org/2/library/…

Charles Duffy Over a year ago

@DanLenski, ...oh, that's a fair objection -- I was using real XPath here; in practice, I use lxml.etree, not the standard-library ElementTree.

Charles Duffy Over a year ago

@DanLenski, ...actually, rereading the question, the OP is using lxml.etree, so it's actually a fair call. :)

Charles Duffy Over a year ago

@iNoob, @userName means "having an attribute called userName". // does a recursive search. * matches an element with any name. That said, if you know that the element with the properties you want will always be called Properties, then you don't need to search off of which attributes it has.

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ROMANIA_engineer · Accepted Answer · 2014-09-09 19:42:42Z

0

You can try to take the element using the tag name and then try to take its attribute (userName is an attribute for Properties):

from lxml import etree as ET

def read_files(files):
    for fi in files:
        doc = ET.parse(fi)
        props = doc.getElementsByTagName('Properties') 
        elm = props[0].attributes['userName']
        print elm.value

answered Sep 9, 2014 at 19:42

ROMANIA_engineer

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