Python – How to convert a string to utf-8 in Python

pythonpython-2.7unicodeutf-8

I have a browser which sends utf-8 characters to my Python server, but when I retrieve it from the query string, the encoding that Python returns is ASCII. How can I convert the plain string to utf-8?

NOTE: The string passed from the web is already UTF-8 encoded, I just want to make Python to treat it as UTF-8 not ASCII.

Best Answer

In Python 2

>>> plain_string = "Hi!"
>>> unicode_string = u"Hi!"
>>> type(plain_string), type(unicode_string)
(<type 'str'>, <type 'unicode'>)

^ This is the difference between a byte string (plain_string) and a unicode string.

>>> s = "Hello!"
>>> u = unicode(s, "utf-8")

^ Converting to unicode and specifying the encoding.

In Python 3

All strings are unicode. The unicode function does not exist anymore. See answer from @Noumenon

Related Solutions

Best way to convert text files between character sets

Stand-alone utility approach

iconv -f ISO-8859-1 -t UTF-8 in.txt > out.txt

-f ENCODING  the encoding of the input
-t ENCODING  the encoding of the output

You don't have to specify either of these arguments. They will default to your current locale, which is usually UTF-8.

Python – How to check whether a file exists without exceptions

If the reason you're checking is so you can do something like if file_exists: open_it(), it's safer to use a try around the attempt to open it. Checking and then opening risks the file being deleted or moved or something between when you check and when you try to open it.

If you're not planning to open the file immediately, you can use os.path.isfile

Return True if path is an existing regular file. This follows symbolic links, so both islink() and isfile() can be true for the same path.

import os.path
os.path.isfile(fname)

if you need to be sure it's a file.

Starting with Python 3.4, the pathlib module offers an object-oriented approach (backported to pathlib2 in Python 2.7):

from pathlib import Path

my_file = Path("/path/to/file")
if my_file.is_file():
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To check a directory, do:

if my_file.is_dir():
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To check whether a Path object exists independently of whether is it a file or directory, use exists():

if my_file.exists():
    # path exists

You can also use resolve(strict=True) in a try block:

try:
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except FileNotFoundError:
    # doesn't exist
else:
    # exists