Python pretty XML printer with lxml

After reading from an existing file with 'ugly' XML and doing some modifications, pretty printing doesn't work. I've tried etree.write(FILE_NAME, pretty_print=True).

I have the following XML:

<testsuites tests="14" failures="0" disabled="0" errors="0" time="0.306" name="AllTests">
    <testsuite name="AIR" tests="14" failures="0" disabled="0" errors="0" time="0.306">
....

And I use it like this:

tree = etree.parse('original.xml')
root = tree.getroot()

...    
# modifications
...

with open(FILE_NAME, "w") as f:
    tree.write(f, pretty_print=True)

Solution 1:

For me, this issue was not solved until I noticed this little tidbit here:

http://lxml.de/FAQ.html#why-doesn-t-the-pretty-print-option-reformat-my-xml-output

Short version:

Read in the file with this command:

>>> parser = etree.XMLParser(remove_blank_text=True)
>>> tree = etree.parse(filename, parser)

That will "reset" the already existing indentation, allowing the output to generate it's own indentation correctly. Then pretty_print as normal:

>>> tree.write(<output_file_name>, pretty_print=True)

Solution 2:

Well, according to the API docs, there is no method "write" in the lxml etree module. You've got a couple of options in regards to getting a pretty printed xml string into a file. You can use the tostring method like so:

f = open('doc.xml', 'w')
f.write(etree.tostring(root, pretty_print=True))
f.close()

Or, if your input source is less than perfect and/or you want more knobs and buttons to configure your out put you could use one of the python wrappers for the tidy lib.

http://utidylib.berlios.de/

import tidy
f.write(tidy.parseString(your_xml_str, **{'output_xml':1, 'indent':1, 'input_xml':1}))

http://countergram.com/open-source/pytidylib

from tidylib import tidy_document
document, errors = tidy_document(your_xml_str, options={'output_xml':1, 'indent':1, 'input_xml':1})
f.write(document)

Solution 3:

fp = file('out.txt', 'w')
print(e.tree.tostring(...), file=fp)
fp.close()

Solution 4:

Here is an answer that is fixed to work with Python 3:

from lxml import etree
from sys import stdout
from io import BytesIO

parser = etree.XMLParser(remove_blank_text = True)
file_obj = BytesIO(text)
tree = etree.parse(file_obj, parser)
tree.write(stdout.buffer, pretty_print = True)

where text is the xml code as a sequence of bytes.