These days, the most popular (and very simple) option is the ElementTree API, which has been included in the standard library since Python 2.5.

The available options for that are:

• ElementTree (Basic, pure-Python implementation of ElementTree. Part of the standard library since 2.5)
• cElementTree (Optimized C implementation of ElementTree. Also offered in the standard library since 2.5. Deprecated and folded into the regular ElementTree as an automatic thing as of 3.3.)
• LXML (Based on libxml2. Offers a rich superset of the ElementTree API as well XPath, CSS Selectors, and more)

Here's an example of how to generate your example document using the in-stdlib cElementTree:

import xml.etree.cElementTree as ET

root = ET.Element("root")
doc = ET.SubElement(root, "doc")

ET.SubElement(doc, "field1", name="blah").text = "some value1"
ET.SubElement(doc, "field2", name="asdfasd").text = "some vlaue2"

tree = ET.ElementTree(root)
tree.write("filename.xml")

I've tested it and it works, but I'm assuming whitespace isn't significant. If you need "prettyprint" indentation, let me know and I'll look up how to do that. (It may be an LXML-specific option. I don't use the stdlib implementation much)

For further reading, here are some useful links:

• API docs for the implementation in the Python standard library
• Introductory Tutorial (From the original author's site)
• LXML etree tutorial. (With example code for loading the best available option from all major ElementTree implementations)

As a final note, either cElementTree or LXML should be fast enough for all your needs (both are optimized C code), but in the event you're in a situation where you need to squeeze out every last bit of performance, the benchmarks on the LXML site indicate that:

• LXML clearly wins for serializing (generating) XML
• As a side-effect of implementing proper parent traversal, LXML is a bit slower than cElementTree for parsing.

You need to

1. Use ET.tostring() to get your xml as a string
2. Use xml.dom.minidom to get a DOM object from the string
3. Use toprettyxml() of DOM object to get the xml as formatted string
4. Add encoding information to the xml declaration part by simply splitting and concating the formatted string
5. Write the string to a file

Code:

import xml.etree.cElementTree as ET
import xml.dom.minidom

m_encoding = 'UTF-8'

root = ET.Element("data")
doc = ET.SubElement(root, "status", date="20210123")
ET.SubElement(doc, "name", name="john").text = "some value1"
ET.SubElement(doc, "class", name="abc").text = "some vlaue2"

dom = xml.dom.minidom.parseString(ET.tostring(root))
xml_string = dom.toprettyxml()
part1, part2 = xml_string.split('?>')

with open("FILE.xml", 'w') as xfile:
    xfile.write(part1 + 'encoding=\"{}\"?>\n'.format(m_encoding) + part2)
    xfile.close()

Output file

<?xml version="1.0" encoding="UTF-8"?>

<data>
    <status date="20210123">
        <name name="john">some value1</name>
        <class name="abc">some vlaue2</class>
    </status>
</data>

You are on the right track save for a few minor syntax and usage issues:

1. class is a Python keyword, you can't use it as a function parameter name (which is essentially what class = 'playlistItem' is doing
2. data-type is not a valid variable name in Python, it will be evaluated as data MINUS type, consider using something like dataType or data_type. There might be ways around this but, IMHO, that would make the code unnecessarily complicated without adding any value (please see Edit #1 on how to do this)

That being said, the following code snippet should give you something usable and you can move on from there. Please feel free to let me know if you need any additional help:

from lxml import etree

data_el = etree.Element('data')

# You can do this in a loop and keep adding new elements
# Note: A deepcopy will be required for subsequent items
li_el = etree.SubElement(data_el, "li", class_name = 'playlistItem', data_type = "local", data_mp3 = "PATH")
a_el = etree.SubElement(li_el, "a", class_name = 'playlistNotSelected', href='#')

print etree.tostring(data_el, encoding='utf-8', xml_declaration = True, pretty_print = True)

This will generate the following output (which you can write to a file):

<?xml version='1.0' encoding='utf-8'?>
<data>
  <li class_name="playlistItem" data_mp3="PATH" data_type="local">
    <a class_name="playlistNotSelected" href="#"/>
  </li>
</data>

Edit #0:

Alternatively, you can also write to a file by converting it to an ElementTree first, e.g.

# Replace sys.stdout with a file object pointing to your object file:
etree.ElementTree(data_el).write(sys.stdout, encoding='utf-8', xml_declaration = True, pretty_print = True)

Edit #1:

Since element attributes are dictionaries, you can use set to specify arbitrary attributes without any restrictions, e.g.

li_el.set('class', 'playlistItem')
li_el.set('data-type', 'local')

ElementTree is a good module for reading xml and writing too e.g.

from xml.etree.ElementTree import Element, SubElement, tostring

root = Element('root')
child = SubElement(root, "child")
child.text = "I am a child"

print(tostring(root))

Output:

<root><child>I am a child</child></root>

See this tutorial for more details and how to pretty print.

Alternatively if your XML is simple, do not underestimate the power of string formatting :)

xmlTemplate = """<root>
    <person>
        <name>%(name)s</name>
        <address>%(address)s</address>
     </person>
</root>"""

data = {'name':'anurag', 'address':'Pune, india'}
print xmlTemplate%data

Output:

<root>
    <person>
        <name>anurag</name>
        <address>Pune, india</address>
     </person>
</root>

You can use string.Template or some template engine too, for complex formatting.