Changing Element Value in Existing XML File Using DOM

Question

I am trying to find examples of how to change an existing xml files Element Value.

Using the following xml example:

<book>
  <title>My Book</title>
  <author>John Smith</author>
</book>

If I wanted to replace the author element value 'John Smith' with 'Jim Johnson' in a Python script using DOM, how would I go about doing so? I've tried to look for examples on this, but have failed in doing so. Any help would be greatly appreciated.

Regards, Rylic

Callahad · Accepted Answer · 2010-03-18 19:09:59Z

5

Presuming

s = '''
<book>
  <title>My Book</title>
  <author>John Smith</author>
</book>'''

DOM would look like:

from xml.dom import minidom

dom = minidom.parseString(s) # or parse(filename_or_file)
for author in dom.getElementsByTagName('author'):
    author.childNodes = [dom.createTextNode("Jane Smith")]

But I'd encourage you to look into ElementTree, it makes working with XML a breeze:

from xml.etree import ElementTree

et = ElementTree.fromstring(s) # or parse(filename_or_file)
for author in et.findall('author'):
    author.text = "Jane Smith"

edited Mar 18, 2010 at 19:09

answered Mar 18, 2010 at 19:01

Callahad

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4 Comments

user296793 Over a year ago

IThanks for your help. I used ElementTree as you suggested, and it works fine. I am able to write to the xml file with the change that was needed. I did notice that when the file is written to, a lock is put on the file. I am presuming that the file is still open for writting. Is there a close method to unlock the file after writting to it with ElementTree?

Callahad Over a year ago

@rylic38 How are you handling writing the file? Can you paste a code sample up on pastie.org?

user296793 Over a year ago

pastie.org is unfortunetly not accessable at work. I'll try to add it here: import os import xml from xml.etree import ElementTree as et path = "C:\\temp\\books.xml" tree = et.parse(path) for author in tree.findall('author'): author.text = "Jane Doe" tree.write(path) When I run this line by line at the command line, the xml file is written to, but is locked. If I exit python, the file is released, and I can then see the change.

user296793 Over a year ago

The format came out unreadable, I seperated each line with "". I hope that makes it more readable. import os *** import xml *** from xml.etree import ElementTree as et path = "C:\\temp\\books.xml"*** tree = et.parse(path)*** for author in tree.findall('author'): *** author.text = "Jane Doe" *** tree.write(path) ***

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