Faithfully Preserve Comments in Parsed XML

Question

I\'d like to preserve comments as faithfully as possible while manipulating XML.

I managed to preserve comments, but the contents are getting XML-escaped.

Answer 1

Looks like both answers from @Martin and @sukhbinder didn't work for me... So made this as a workable completed solution on python 3.x

from xml.etree import ElementTree

string = '''<?xml version="1.0"?>
<data>
    <!--Test
    -->
    <country name="Liechtenstein">
        <rank>1</rank>
        <year>2008</year>
        <gdppc>141100</gdppc>
        <neighbor name="Austria" direction="E"/>
        <neighbor name="Switzerland" direction="W"/>
    </country>
</data>'''

class CommentedTreeBuilder(ElementTree.TreeBuilder):
    def comment(self, data):
        self.start(ElementTree.Comment, {})
        self.data(data)
        self.end(ElementTree.Comment)

parser = ElementTree.XMLParser(target=CommentedTreeBuilder())
tree = ElementTree.fromstring(string, parser)
print(tree.find("./*[0]").text)
# or ElementTree.parse(filename, parser)

Answer 2

Tested with Python 2.7 and 3.5, the following code should work as intended.

#!/usr/bin/env python
# CommentedTreeBuilder.py
from xml.etree import ElementTree

class CommentedTreeBuilder(ElementTree.TreeBuilder):
    def comment(self, data):
        self.start(ElementTree.Comment, {})
        self.data(data)
        self.end(ElementTree.Comment)

Then, in the main code use

parser = ElementTree.XMLParser(target=CommentedTreeBuilder())

as the parser instead of the current one.

By the way, comments work correctly out of the box with lxml. That is, you can just do

import lxml.etree as ET
tree = ET.parse(filename)

without needing any of the above.

Answer 3

Martin's Code didn't work for me. I modified the same with the following which works as intended.

import xml.etree.ElementTree as ET

class CommentedTreeBuilder(ET.XMLTreeBuilder):
    def __init__(self, *args, **kwargs):
        super(CommentedTreeBuilder, self).__init__(*args, **kwargs)
        self._parser.CommentHandler = self.comment

    def comment(self, data):
        self._target.start(ET.Comment, {})
        self._target.data(data)
        self._target.end(ET.Comment)

This is the test

    parser=CommentedTreeBuilder()
    tree = ET.parse(filename, parser)
    tree.write('out.xml')

Answer 4

Python 3.8 added the insert_comments argument to TreeBuilder which:

class xml.etree.ElementTree.TreeBuilder(element_factory=None, *, comment_factory=None, pi_factory=None, insert_comments=False, insert_pis=False)

When insert_comments and/or insert_pis is true, comments/pis will be inserted into the tree if they appear within the root element (but not outside of it).

Example:

parser = ElementTree.XMLParser(target=ElementTree.TreeBuilder(insert_comments=True))