Search code examples
pythonxmlcommentselementtree

Add comment to beginning of document

Using ElementTree, how do I place a comment just below the XML declaration and above the root element?

I have tried root.append(comment), but this places the comment as the last child of root. Can I append the comment to whatever is root's parent?

Thanks.

Solution

  • Here is how a comment can be added in the wanted position (after XML declaration, before root element) with lxml, using the addprevious() method.

    from lxml import etree

root = etree.fromstring('<root><x>y</x></root>')
comment = etree.Comment('This is a comment')
root.addprevious(comment)  # Add the comment as a preceding sibling

etree.ElementTree(root).write("out.xml",
                              pretty_print=True,
                              encoding="UTF-8",
                              xml_declaration=True)

    Result (out.xml):

    <?xml version='1.0' encoding='UTF-8'?>
<!--This is a comment-->
<root>
  <x>y</x>
</root>