[SOLVED] Preserve line breaks in XML attributes when parsing with lxml

Preserve line breaks in XML attributes when parsing with lxml

I'm trying to batch-process a couple of XML files through a python script, with the XML files having line breaks in some of their attributes like so:

<?xml version='1.0' encoding='UTF-8'?>
<xml>
    <test value="This is
    a test

    with line breaks
    "/>
</xml>

However, I noticed that line breaks within attributes are removed when parsing this file. For example, the following script:

import lxml.etree as ET

with open("input.xml", "r", encoding="utf-8") as f:
    source = ET.parse(f)
    root = source.getroot()
    dest = ET.ElementTree(root)
    dest.write("output.xml", encoding="utf-8", xml_declaration=True)

would produce the following output file:

<?xml version='1.0' encoding='UTF-8'?>
<xml>
    <test value="This is  a test   with line breaks  "/>
</xml>

While this seems to be in line with W3Cs recommendations as per this related answer, is there a way to use xml.etree or lxml.etree for modifying the XML file without removing those line breaks?

Solution

One dirty hack what I think could be with bs4:

import re
from bs4 import BeautifulSoup

# Read XML as text 
with open("input.xml", encoding="utf-8") as f:
    xml_text = f.read()

# extract attributevalue per regex and store it e.g. in a dict key, value
match = re.search(r'value="(.*?)"', xml_text, re.DOTALL)
raw_value = match.group(1) if match else None
print("Raw string: ", repr(raw_value))
print()

# Parse your xml (replace attribute by placeholder e.g. key if necessary))
soup = BeautifulSoup(xml_text, "xml")
test_tag = soup.find("test")

# reset attributvalue from dict
if raw_value is not None:
    test_tag["value"] = raw_value

# result
print(soup.prettify())

Output:

Raw string:  'This is\n    a test\n\n    with line breaks\n    '

<?xml version="1.0" encoding="utf-8"?>
<xml>
 <test value="This is
    a test

    with line breaks
    "/>
</xml>