Saving modified xml error 'ElementTree' object has no attribute 'tag'

Question

Code

When running the following code I cannot save the output as an xml file as I get the following error AttributeError: 'ElementTree' object has no attribute 'tag'(in traceback). There is a similarly named question on SO but I do not believe it is relevant to mine as it was to do with parsing from the root node, not saving.

Code

import xml.etree.ElementTree as ET
print('\n'*5)

xmlfile = 'widget.XML'

tree = ET.parse(xmlfile)
root = tree.getroot()

#ET.dump(tree)# prints the xml file to console,shows xml indentation
print('\n'*2)
for elm in root.findall("./Common/ForceBinary"):
    print(elm.attrib)
    elm.attrib = {'type': 'integer', 'value': '0'}

with open("new_file.xml", "w") as f:
    f.write(ET.tostring(tree))

Traceback

{'type': 'integer', 'value': '1'}
Traceback (most recent call last):
  File "/Users/user/Desktop/MY_PY/x_08.py", line 16, in <module>
    f.write(ET.tostring(tree))
  File "/Users/user/opt/anaconda3/lib/python3.7/xml/etree/ElementTree.py", line 1136, in tostring
    short_empty_elements=short_empty_elements)
  File "/Users/user/opt/anaconda3/lib/python3.7/xml/etree/ElementTree.py", line 777, in write
    short_empty_elements=short_empty_elements)
  File "/Users/user/opt/anaconda3/lib/python3.7/xml/etree/ElementTree.py", line 901, in _serialize_xml
    tag = elem.tag
AttributeError: 'ElementTree' object has no attribute 'tag'

Mike Roll · Accepted Answer · 2020-12-14 16:33:28Z

3

ElementTree.tostring() operates on an Element, which is not the same as ElementTree. You've already extracted the root node via tree.getroot() - you just need ET.tostring(root) instead.

The reason the API is this way is because Element is intended as the data structure for an in-memory parsed XML object, while ElementTree is mostly just a serialization-deserialization helper (perhaps the Tree naming was not the best idea) to bridge those Elements with the outside world.

A related question about the difference between the two: What is the difference between a ElementTree and an Element? (python xml)

edited Dec 14, 2020 at 16:33

answered Dec 14, 2020 at 15:30

Mike Roll

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3 Comments

Windy71 Over a year ago

How do you then write the xml to a file?

Mike Roll Over a year ago

As you would any other string and as you tried in your question, open a file and f.write() to it. You've asked for an explanation why the original solution didn't work and here it is - however if writing XML to a file is all you need, the tree.write() shortcut is the way to go.

Windy71 Over a year ago

Thank you Mike, much appreciated.

Windy71 · Accepted Answer · 2020-12-14 15:17:15Z

2

After trying quite a few methods to write the output to an xml file this is the line that worked (I don't know why, if anyone has an explanation I would be happy to accept it as the answer).

tree.write("sdn_edit2.xml")

answered Dec 14, 2020 at 15:17

Windy71

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