inserting newlines in xml file generated via xml.etree.ElementTree in python

Question

I have created a xml file using xml.etree.ElementTree in python. I then use

tree.write(filename, "UTF-8") 

to write out the document to a file.

But when I open filename using a text editor, there are no newlines between the tags. Everything is one big line

How can I write out the document in a "pretty printed" format so that there are new lines (and hopefully indentations etc) between all the xml tags?

Answer 1

I found a new way to avoid new libraries and reparsing the xml. You just need to pass your root element to this function (see below explanation):

def indent(elem, level=0):
    i = "
" + level*"  "
    if len(elem):
        if not elem.text or not elem.text.strip():
            elem.text = i + "  "
        if not elem.tail or not elem.tail.strip():
            elem.tail = i
        for elem in elem:
            indent(elem, level+1)
        if not elem.tail or not elem.tail.strip():
            elem.tail = i
    else:
        if level and (not elem.tail or not elem.tail.strip()):
            elem.tail = i

There is an attribute named "tail" on xml.etree.ElementTree.Element instances. This attribute can set an string after a node:

"<a>text</a>tail"

I found a link from 2004 telling about an Element Library Functions that uses this "tail" to indent an element.

Example:

root = ET.fromstring("<fruits><fruit>banana</fruit><fruit>apple</fruit></fruits>""")
tree = ET.ElementTree(root)

indent(root)
# writing xml
tree.write("example.xml", encoding="utf-8", xml_declaration=True)

Result on "example.xml":

<?xml version='1.0' encoding='utf-8'?>
<fruits>
    <fruit>banana</fruit>
    <fruit>apple</fruit>
</fruits>