How to rename an attribute name with python LXML?

user_191246 0
Viewed 99

It's fairly well documented how to get and set the value of an attribute with LXML, but is there a way to rename the name of an existing attribute?

The goal is to get from

<element old="cheese"/>

to

<element new="cheese"/>

What I am currently doing is a bit convoluted — deleting the attribute and then re-adding it with a new name and the old value:

from io import StringIO
from lxml import etree

doc = StringIO('<element old="cheese"/>')

tree = etree.parse(doc)
elem = tree.getroot()

attr_value = elem.attrib['old']
del elem.attrib['old']
elem.attrib['new'] = attr_value

Is there a way to rename an attribute directly instead of deleting and re-adding with a new key?

lxml xml python
2 Answers

First I wish I could upvote your question twice because you gave a minimal, reproducible example that I could copy/paste/run. Those new to stack overflow should take note! I suppose it's because users that have been around as long as you and I don't ask as many questions.

I don't think what you're doing is that convoluted, but since .attrib is a dict you could do something like this instead:

elem.attrib['new'] = elem.attrib.pop('old')

Full example:

from io import StringIO
from lxml import etree

doc = StringIO('<element old="cheese"/>')

tree = etree.parse(doc)
elem = tree.getroot()

elem.attrib['new'] = elem.attrib.pop('old')

print(etree.tostring(tree).decode())

Printed output...

<element new="cheese"/>
user_3170520

The below does the same with python "out of the box" python xml lib - ElementTree .

import xml.etree.ElementTree as ET

xml = '''<element old="cheese"/>'''
root = ET.fromstring(xml)
root.attrib['new'] = root.attrib.pop('old')
ET.dump(root)

output

<element new="cheese" />
user_4150160
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