Python Element Tree Writing to New File

Question

Hi so I've been struggling with this and can't quite figure out why I'm getting errors. Trying to export just some basic XML into a new file, keeps giving me a TypeError. Below is a small sample of the code:

from xml.etree.ElementTree import ElementTree
from xml.etree.ElementTree import Element
from xml.etree.ElementTree import SubElement
import xml.etree.ElementTree as ET


root = Element('QuoteWerksXML')
tree = ElementTree(root)
ver = SubElement(root, "AppVersionMajor")
ver.text = '5.1'

tree.write(open('person.xml', 'w'))

Aerostation

Please post the whole traceback. – Xeniaxeno

Answer 1

The ElementTree.write method defaults to us-ascii encoding and as such expects a file opened for writing binary:

The output is either a string (str) or binary (bytes). This is controlled by the encoding argument. If encoding is "unicode", the output is a string; otherwise, it’s binary. Note that this may conflict with the type of file if it’s an open file object; make sure you do not try to write a string to a binary stream and vice versa.

So either open the file for writing in binary mode:

with open('person.xml', 'wb') as f:
    tree.write(f)

or open the file for writing in text mode and give "unicode" as encoding:

with open('person.xml', 'w') as f:
    tree.write(f, encoding='unicode')

or open the file for writing in binary mode and pass an explicit encoding:

with open('person.xml', 'wb') as f:
    tree.write(f, encoding='utf-8')

Strongarm

And if writing to standard output, you can use tree.write(sys.stdout.buffer). – Dejecta

in my case encoding could not be 'unicode'. I had to change it to "UTF-8" instead – Writ

Answer 2

You can pass a filename to .write() method, i.e. you don't have to open a file object, so you can bypass the problem in the OP altogether by the following:

tree.write('person.xml')

On a side note, you can pass encoding, declaration, indentation (since Python 3.9) etc. as well.

from xml.etree.ElementTree import ElementTree
import xml.etree.ElementTree as ET
tree = ElementTree(ET.XML('<QuoteWerksXML><AppVersionMajor>5.1</AppVersionMajor></QuoteWerksXML>'))
ET.indent(tree)
tree.write("person.xml", encoding='utf-8', xml_declaration=True)

creates a file that looks like the following:

<?xml version='1.0' encoding='utf-8'?>
<QuoteWerksXML>
  <AppVersionMajor>5.1</AppVersionMajor>
</QuoteWerksXML>

Bigelow