Converting bytes to unicode that works both in python2 and 3

[Hanne Moa]

I got to start a new django 1.8-project in python 3.4 for once, and happily coded away. Turns out, the PaaS it needs to run on has a broken python 3.4, so... my code now needs to work in 2.7.8.

Everything works in both versions except I need to read from an uploaded file, bot in the web and from the commandline. In the management command I can do:

import io
with io.open(fieldname, 'rt', encoding='UTF-8') as F: do_stuff(F)

... and it works in both 2.7.8 and 3.4.x.

But a FileField in Python 3 reads stuff as bytes. So in the form, I need to check whether the chunk of data I get is bytes, and if it is, convert it to unicode from 'UTF-8'.

How to do that? It'll probably involve six in some way but the docs for six, and django's "how to have things run on both python 2 and 3"-docs, could be better.

[Vernon D. Cole]

if sys.version_info >= (3,0):
    def str2bytes(sval):
        return sval.encode("latin1")
    unicode = str
else:
    def str2bytes(sval):
        if isinstance(sval, str):
            return sval
        return sval.encode("latin1")

This is what I use to solve the opposite problem.  It should give you an idea how to go about it.