How can I percent-encode URL parameters in Python?

Python 2

From the documentation:

urllib.quote(string[, safe])

Replace special characters in string using the %xx escape. Letters, digits, and the characters '_.-' are never quoted. By default, this function is intended for quoting the path section of the URL.The optional safe parameter specifies additional characters that should not be quoted — its default value is '/'

That means passing '' for safe will solve your first issue:

>>> urllib.quote('/test')
'/test'
>>> urllib.quote('/test', safe='')
'%2Ftest'

About the second issue, there is a bug report about it. Apparently it was fixed in Python 3. You can workaround it by encoding as UTF-8 like this:

>>> query = urllib.quote(u"Müller".encode('utf8'))
>>> print urllib.unquote(query).decode('utf8')
Müller

By the way, have a look at urlencode.

Python 3

>>> import urllib.parse
>>> print(urllib.parse.quote("Müller".encode('utf8')))
M%C3%BCller
>>> print(urllib.parse.unquote("M%C3%BCller"))
Müller

In Python 3, urllib.quote has been moved to urllib.parse.quote, and it does handle Unicode by default.

>>> from urllib.parse import quote
>>> quote('/test')
'/test'
>>> quote('/test', safe='')
'%2Ftest'
>>> quote('/El Niño/')
'/El%20Ni%C3%B1o/'

I think module requests is much better. It's based on urllib3.

You can try this:

>>> from requests.utils import quote
>>> quote('/test')
'/test'
>>> quote('/test', safe='')
'%2Ftest'

_{My answer is similar to Paolo's answer.}

If you're using Django, you can use urlquote:

>>> from django.utils.http import urlquote
>>> urlquote(u"Müller")
u'M%C3%BCller'

Note that changes to Python mean that this is now a legacy wrapper. From the Django 2.1 source code for django.utils.http:

A legacy compatibility wrapper to Python's urllib.parse.quote() function.
(was used for unicode handling on Python 2)