Writing Unicode to database using ODBC

John Machin sjmachin at lexicon.net
Thu Sep 4 01:28:54 CEST 2008


On Sep 4, 3:11 am, Mudcat <mnati... at gmail.com> wrote:
[snip]

> However, now that I've got all that working I'd like to simply take
> the unicode data from the xml parser and then pass it directly into
> the database (which is currently set up for unicode data). I've run

What database? What does "set up for unicode data" mean? If you are
using MS SQL Server, are your text columns defined to be varchar or
nvarchar or something else?

> into problems and just can't figure why this isn't working.
>
> The breakdown is occurring when I try to execute the db query:
>
>           cur.execute( query )
>
> Fairly straightforward. I get the following error:
>
>   File "atp_alt.py", line 273, in dbWrite
>     cur.execute( query )
> UnicodeEncodeError: 'ascii' codec can't encode character u'\u201c' in
> position 3
> 79: ordinal not in range(128)
>
> I've verified that query is of type unicode by checking the type a
> statement or two earlier (output: <type 'unicode'>).

> So then I thought maybe the odbc execute just can't handle unicode
> data.

It appears to be expecting a str object, not a unicode object.

> But when I do the following command:
>
>           query = query.encode('utf-8')
>
> It actually works. So apparently execute can handle unicode data.

"not crashing" != "works"

> The
> problem now is that basically the data has been encoded twice and is
> in the wrong format when I pull it from the database:

No, your utf8 string has been DEcoded using some strange encoding.

>
> >>> a
>
> u'+CMGL: (\xe2\u20ac\u0153REC UNREAD\xe2\u20ac\x9d,\xe2\u20ac\x9dREC
> READ\xe2\u20ac\x9d,\xe2\u20ac\x9dSTO UNSENT\xe2\u20ac\x9d,\xe2\u20ac
> \x9dSTO SENT\xe2\u20ac\x9d,\xe2\u20ac\x9dALL\xe2\u20ac\x9d) OK'>>> print a
>
> +CMGL: (“REC UNREAD†,†REC READ†,†STO UNSENT†,†STO SENTâ
> € ,†ALL†) OK

It would help very much if you showed the repr() of your input unicode
text.

Observation: the first bunch of rubbish output (\xe2\u20ac\u0153)
differs from all the others (\xe2\u20ac\x9d).

>
> The non-alpha characters should be double-quotes.

What "double-quotes" character(s)? Unicode has several: U+0022
(unoriented), U+201C (left), U+201D (right), plus more exotic ones.

> It works correctly
> if I copy/paste into the editor:
>
> >>> d
> u'\u201cREC'
> >>> print d
> “REC
> >>> d.encode('utf-8')
> '\xe2\x80\x9cREC'

More observations:

>>> u'\u201c'.encode('utf8')
'\xe2\x80\x9c'
>>> u'\u201c'.encode('utf8').decode('cp1252')
u'\xe2\u20ac\u0153'

Aha! The first load of rubbish! However:

>>> u'\u201d'.encode('utf8')
'\xe2\x80\x9d'
>>> u'\u201d'.encode('utf8').decode('cp1252')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "C:\Python25\lib\encodings\cp1252.py", line 15, in decode
    return codecs.charmap_decode(input,errors,decoding_table)
UnicodeDecodeError: 'charmap' codec can't decode byte 0x9d in position
2: character maps to <undefined>
>>>

Hmmm, try the ferschlugginer mcbs encoding:

>>> u'\u201d'.encode('utf8').decode('mbcs')
u'\xe2\u20ac\x9d'
>>> u'\u201c'.encode('utf8').decode('mbcs')
u'\xe2\u20ac\u0153'
>>>

So, if you must persist with the odbc module, either encode your
unicode text with mbcs, not utf8, or find out how to "set up for
unicode data" so that utf8 is the default.

You may like to consider using pyODBC or mxODBC instead of odbc.

HTH,
John



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