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From: JB on 17 May 2010 18:10
I'm working on the webapp of our company intranet and I had a question
about proper handling of user input that's causing encoding issues.

Some of the uesrs take notes in Microsoft Office and copy/paste these
into textarea's of the webapp. Some of the characters from Word such
as hypens (–) and apostrophes (’) are in an odd encoding. When passed
to the database using sqlalchemy they appear as – and other
characters.

What's the proper handling (conversion?) of user input before it gets
to my database. Do I need to start making a list of the offending
characters and .replace them? Or is there a means to decode/encode the
user input to something more generic? Thanks for your time.
From: Neil Hodgson on 17 May 2010 19:05
JB:

> as hypens (�) and apostrophes (�) are in an odd encoding. When passed
> to the database using sqlalchemy they appear as – and other
> characters.

The encoding is UTF-8. Normally the best way to handle encodings is
to convert to Unicode strings (unicode(s, "UTF-8")) as soon as possible
and perform most processing in Unicode.

Neil
From: Bryan on 17 May 2010 22:38
Neil Hodgson wrote:
> JB:
>
> > as hypens (–) and apostrophes (’) are in an odd encoding. When passed
> > to the database using sqlalchemy they appear as – and other
> > characters.
>
>    The encoding is UTF-8. Normally the best way to handle encodings is
> to convert to Unicode strings (unicode(s, "UTF-8")) as soon as possible
> and perform most processing in Unicode.

Good advice to work in Unicode (and in Python 3.X str is unicode), but
I'd guess the encoding he's getting is "Windows-1252". The default
character set of HTTP is ISO-8859-1, but Microsoft likes to use
Windows-1252 in it's place.

What to do about it? First, try specifying utf-8 in the form
containing the textarea, as in

<form action="process.cgi" accept-charset="utf-8">

Note that specifying ISO-8859-1 will not work, in that Microsoft will
still use Windows-1252. I've heard they've gotten better at supporting
utf-8, but I haven't tested.

When a request comes in, check for a Content-Type header that names
the character set, which should be:

Content-Type: application/x-www-form-urlencoded; charset=utf-8

Then you con decode to a unicode object as Neil Hodgson explained.

In case you still have to deal with Windows-1252, Python knows how to
translate Windows-1252 to the best-fit in Unicode. In current Python
2.x:

ustring = unicode(raw_string, 'Windows-1252')

In Python 3.X, what comes from a socket is bytes, and str means
unicode:

ustring = str(raw_bytes, 'Windows-1252')


Of course this all assumes that JB's database likes Unicode. If it
chokes, then alternatives include encoding back to utf-8 and storing
as binary, or translating characters to some best-fit in the set the
database supports.


--
--Bryan Olson
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