Use xml.etree.ElementTree to print nicely formatted xml files

Question

I am trying to use xml.etree.ElementTree to write out xml files with Python. The issue is that they keep getting generated in a single line. I want to be able to easily reference them so if it's possible I would really like to be able to have the file written out cleanly.

This is what I am getting:

<Language><En><Port>Port</Port><UserName>UserName</UserName></En><Ch><Port>IP地址</Port><UserName>用户名称</UserName></Ch></Language>

This is what I would like to see:

<Language>
    <En>
        <Port>Port</Port>
        <UserName>UserName</UserName>
    </En>
    <Ch>
        <Port>IP地址</Port>
        <UserName>用户名称</UserName>
    </Ch>
</Language>

This is not a true duplicate: The other question leaves the possibility to use _any_ XML library. This question asks specifically for a solution when you are already working with the _built-in element tree_ library. Imho it makes perfect sense to ask this question specifically for this library, because it is apparently a missing feature!? — bluenote10, Dec 24 '13 at 15:36
you can use a function like the one i found here: http://effbot.org/zone/element-lib.htm#prettyprint — Simon Meyer, Dec 28 '16 at 17:41
@bluenote10 When someone report, the other people will re-report, just to follow something. I'm from Colombia, so sorry for my bad english. — Máxima Alekz, Dec 16 '17 at 16:32
Related: [Python Bug Tracker - Issue report for Pretty Printing](https://bugs.python.org/issue14465); and [GitHub - proposed pull request](https://github.com/python/cpython/pull/4016). — Stevoisiak, Apr 27 '18 at 20:23
You can check my answer here: https://stackoverflow.com/a/63373633/268627. As of Python 3.9 there will be a new indent function built-in. — o15a3d4l11s2, Aug 12 '20 at 09:29

score 72 · Accepted Answer · edited Apr 27 '18 at 20:14

72

You can use the function toprettyxml() from xml.dom.minidom in order to do that:

def prettify(elem):
    """Return a pretty-printed XML string for the Element.
    """
    rough_string = ElementTree.tostring(elem, 'utf-8')
    reparsed = minidom.parseString(rough_string)
    return reparsed.toprettyxml(indent="\t")

The idea is to print your Element in a string, parse it using minidom and convert it again in XML using the toprettyxml function.

Source: http://pymotw.com/2/xml/etree/ElementTree/create.html

edited Apr 27 '18 at 20:14

Stevoisiak

23,794
27
122
225

answered Jul 01 '13 at 10:35

Maxime Chéramy

17,761
8
54
75

21

This adds extra lines. Not sure I'd call that pretty. – Steve Cohen Oct 03 '14 at 22:32
5

For a large file though this requires reparsing the whole XML. hmm... – Michael Scott Asato Cuthbert Sep 02 '15 at 23:01
2

@steve: Not only does that add another line, the data is processed like this: convert the XML tree to string, convert it back to an XML tree, and then convert it back to a string. That's not pretty, that's completely out of the question. – Regis May May 20 '18 at 12:29
2

At least it works out of the box with a normal Python installation. – Raúl Salinas-Monteagudo Mar 28 '19 at 12:10
@RaúlSalinas-Monteagudo Not for my Python installation. Unfortunately I have the displeasure of working in an environment where lxml, bs4, xmltodict, stdio, numpy, etc. don't exist and can't be easily installed. Sorry just ranting... Now if only I could find a one-line solution for an out-dated and unsupported Python 2.7... – FriskySaga May 14 '20 at 02:40
This answer does not refer to `xml.etree`. – buhtz Jan 12 '21 at 09:30
@buhtz `ElementTree` is imported from `xml.etree` – Maxime Chéramy Jan 12 '21 at 16:01

mmmmmm · Answer 2 · 2019-09-27T10:03:42.120

24

You could use the library lxml (Note top level link is now spam) , which is a superset of ElementTree. Its tostring() method includes a parameter pretty_print - for example:

>>> print(etree.tostring(root, pretty_print=True))
<root>
  <child1/>
  <child2/>
  <child3/>
</root>

edited Sep 27 '19 at 10:03

answered Jul 01 '13 at 10:39

mmmmmm

32,227
27
88
117

"pretty_print=True" does not work for me, and I do not why – vanke xu Jan 26 '19 at 07:03
2

etree.tostring(root, pretty_print=True).decode() works! – vanke xu Jan 26 '19 at 07:07
1

Yes. But [lxml](https://lxml.de/) does not support default namespace very well. – Hanson Sep 27 '19 at 02:25
It supportds namespaces much better than other libraries :) Also that link is now dead and a spam – mmmmmm Sep 27 '19 at 10:03
This answer does not refer to `xml.etree`. – buhtz Jan 12 '21 at 09:30
@buhtz No but it does tell you how to get a prettyprint without changing much code - only need to change the import rather than using minidom which has a totally different API – mmmmmm Jan 12 '21 at 09:36

Use xml.etree.ElementTree to print nicely formatted xml files

2 Answers2

Linked