Reading XML file and fetching its attributes value

问题:

I have this XML file:

<domain type='kmc' id='007'>
  <name>virtual bug</name>
  <uuid>66523dfdf555dfd</uuid>
  <os>
    <type arch='xintel' machine='ubuntu'>hvm</type>
    <boot dev='hd'/>
    <boot dev='cdrom'/>
  </os>
  <memory unit='KiB'>524288</memory>
  <currentMemory unit='KiB'>270336</currentMemory>
  <vcpu placement='static'>10</vcpu>

Now, I want parse this and fetch its attribute value. For instance, I want to fetch the uuid field. So what should be the proper method to fetch it, in Python?

回答1:

Here's an lxml snippet that extracts an attribute as well as element text (your question was a little ambiguous about which one you needed, so I'm including both):

from lxml import etree
doc = etree.parse(filename)

memoryElem = doc.find('memory')
print memoryElem.text        # element text
print memoryElem.get('unit') # attribute

You asked (in a comment on Ali Afshar's answer) whether minidom (2.x, 3.x) is a good alternative. Here's the equivalent code using minidom; judge for yourself which is nicer:

import xml.dom.minidom as minidom
doc = minidom.parse(filename)

memoryElem = doc.getElementsByTagName('memory')[0]
print ''.join( [node.data for node in memoryElem.childNodes] )
print memoryElem.getAttribute('unit')

lxml seems like the winner to me.

回答2:

XML

<data>
    <items>
        <item name="item1">item1</item>
        <item name="item2">item2</item>
        <item name="item3">item3</item>
        <item name="item4">item4</item>
    </items>
</data>

Python :

from xml.dom import minidom
xmldoc = minidom.parse('items.xml')
itemlist = xmldoc.getElementsByTagName('item') 
print "Len : ", len(itemlist)
print "Attribute Name : ", itemlist[0].attributes['name'].value
print "Text : ", itemlist[0].firstChild.nodeValue
for s in itemlist :
    print "Attribute Name : ", s.attributes['name'].value
    print "Text : ", s.firstChild.nodeValue

回答3:

etree, with lxml probably:

root = etree.XML(MY_XML)
uuid = root.find('uuid')
print uuid.text

回答4:

Other people can tell you how to do it with the Python standard library. I'd recommend my own mini-library that makes this a completely straight forward.

>>> obj = xml2obj.xml2obj("""<domain type='kmc' id='007'>
... <name>virtual bug</name>
... <uuid>66523dfdf555dfd</uuid>
... <os>
... <type arch='xintel' machine='ubuntu'>hvm</type>
... <boot dev='hd'/>
... <boot dev='cdrom'/>
... </os>
... <memory unit='KiB'>524288</memory>
... <currentMemory unit='KiB'>270336</currentMemory>
... <vcpu placement='static'>10</vcpu>
... </domain>""")
>>> obj.uuid
u'66523dfdf555dfd'

http://code.activestate.com/recipes/534109-xml-to-python-data-structure/

回答5:

I would use lxml and parse it out using xpath //UUID

回答6:

Above XML does not have closing tag, It will give

etree parse error: Premature end of data in tag

Correct XML is:

<domain type='kmc' id='007'>
  <name>virtual bug</name>
  <uuid>66523dfdf555dfd</uuid>
  <os>
    <type arch='xintel' machine='ubuntu'>hvm</type>
    <boot dev='hd'/>
    <boot dev='cdrom'/>
  </os>
  <memory unit='KiB'>524288</memory>
  <currentMemory unit='KiB'>270336</currentMemory>
  <vcpu placement='static'>10</vcpu>
</domain>