XML

Important

Check out the XML snippets page.

Note

The core components (of ElementTree) are also shipped with Python 2.5 and later…

Sample

Read

Note

The XML snippets page has a python 3 example which iterates over attributes and tags.

Tip

The XML snippets page has an example using xmltodict. If the file can fit in memory this is probably an easier option.

An older python 2 example which iterates over tags:

from xml.etree import ElementTree as ET
tree = ET.parse('pom.xml')
r = tree.getroot()
def trav(node, indent=0):
    for c in node.getchildren():
        print ' '*indent, c.tag, ':', c.text
        trav(c, indent+1)
trav(r)

…using the trav method above, we can iterate over a string:

>>> xml = '<code><detail><userId>79918</userId><totalPoints>8</totalPoints></detail></code>'
>>> tree = ET.fromstring(xml)
>>> trav(tree)

Another (slightly confusing) sample:

>>> testtext = """
...     <html><body>hello world.  <i>foo!</i>
...     </body></html>"""
>>> testtext
'\n    <html><body>hello world.  <i>foo!</i>\n    </body></html>'
>>> tree = ET.fromstring(testtext)
>>> len(tree)
1
>>> tree[0].text
'hello world.  '
>>> tree[0][0].text
'foo!'
>>> for italicNode in tree.findall('.//i'):
...     print italicNode.text
...
foo!
>>> ET.tostring(tree)
'<html><body>hello world.  <i>foo!</i>\n    </body></html>'
>>>

Create

from xml.etree import ElementTree as ET
root = ET.Element('html')
head = ET.SubElement(root, 'head')
title = ET.SubElement(head, 'title')
title.text = 'Page Title'
body = ET.SubElement(root, 'body')
body.set('bgcolor', '#ffffff')
body.text = 'Hello World!'
tree = ET.ElementTree(root)
tree.write('temp.xml')

Encoding

e.g. using the tree object from the Create sample (above):

tree.write('out.xml', encoding="UTF-8")

Introducing ElementTree 1.3, XML Output

Pretty Print

We can produce a pretty print using this method:

def indent(elem, level=0):
    i = "\n" + level*"  "
    if len(elem):
        if not elem.text or not elem.text.strip():
            elem.text = i + "  "
        if not elem.tail or not elem.tail.strip():
            elem.tail = i
        for elem in elem:
            indent(elem, level+1)
        if not elem.tail or not elem.tail.strip():
            elem.tail = i
    else:
        if level and (not elem.tail or not elem.tail.strip()):
            elem.tail = i

e.g. using the tree object from the Create sample (above):

indent(tree.getroot())
tree.write('pretty.xml', encoding="ISO-8859-1")

#!/usr/bin/env python
import xml.dom.minidom as md
import sys

pretty_print = lambda f: '\n'.join([line for line in md.parse(open(f)).toprettyxml(indent=' '*2).split('\n') if line.strip()])

if __name__ == "__main__":
   if len(sys.argv)>=2:
      print pretty_print(sys.argv[1])
   else:
      sys.exit("Usage: %s [xmlfile]" % sys.argv[0])

find and findAll

For this example we will parse a standard Maven pom.xml file.

To find elements using XPath like syntax, we first need to know the namespace:

from xml.etree import ElementTree as ET
tree = ET.parse('sample-app/pom.xml')
root = tree.getroot()
for element in root: print element.tag
   ...:
{http://maven.apache.org/POM/4.0.0}modelVersion
{http://maven.apache.org/POM/4.0.0}groupId
{http://maven.apache.org/POM/4.0.0}artifactId
...

Don’t forget to include the namespace when searching for elements:

e = tree.find('{http://maven.apache.org/POM/4.0.0}artifactId')
e.text
'sample-app'

To find all elements in the xml file, prefix the query with \/\/:

e = tree.findall('//{http://maven.apache.org/POM/4.0.0}artifactId')
for i in e:
    print i.text
   ....:
sample-app
junit

To search down through a specific path:

e = tree.find('{http://maven.apache.org/POM/4.0.0}dependencies/{http://maven.apache.org/POM/4.0.0}dependency/{http://maven.apache.org/POM/4.0.0}artifactId')
e.text
'junit'