Re: [Python-sybase-misc] Sybase type names?

[Sébastien S. <sa...@us...>]

Hi Skip,

I should definitely write some documentation about this.

In the mean time, here is an example that I use myself to shift the 
origin of Sybase dates and datetimes so that it corresponds to the ones 
used by Oracle:

import Sybase
from datetime import date, datetime

MY_DATE_ORIGIN = date(1752, 9, 14)
MY_DATETIME_ORIGIN = datetime(1752, 9, 14, 0, 0)
SYBASE_DATE_ORIGIN = date(1753, 1, 1)
SYBASE_DATETIME_ORIGIN = datetime(1753, 1, 1, 0, 0)

outputmap = dict(Sybase.DateTimeAsPython)

def change_outdatetime_origin(val):
     d = datetime(val.year, val.month + 1, val.day,
                  val.hour, val.minute,
                  val.second, val.msecond * 1000)
     if d.date() == SYBASE_DATE_ORIGIN:
         d = MY_DATETIME_ORIGIN
     return d
def change_outdate_origin(val):
     d = date(val.year, val.month + 1, val.day)
     if d == SYBASE_DATE_ORIGIN:
         d = MY_DATE_ORIGIN
     return d

outputmap.update({
     Sybase.CS_DATETIME_TYPE: change_outdatetime_origin,
     Sybase.CS_DATETIME4_TYPE: change_outdatetime_origin,
     Sybase.CS_DATE_TYPE: change_outdate_origin })


def change_indate_origin(val):
     if val < SYBASE_DATE_ORIGIN:
         val = SYBASE_DATE_ORIGIN
     return val
def change_indatetime_origin(val):
     if val < SYBASE_DATETIME_ORIGIN:
         val = SYBASE_DATETIME_ORIGIN
     return val

inputmap = { datetime: change_indatetime_origin,
              date: change_indate_origin }

conn = Sybase.connect(server, user, password, database, 
inputmap=inputmap, outputmap=outputmap)


regards

--
Sébastien Sablé

sk...@po... a écrit :
> In the python-sybase documentation it says 0.39 implements Carsten Haese's
> type mapping extension to the DB-API.  That specification is a bit ambiguous
> when it comes to naming the keys in the input and output maps.  It says:
> 
>     When a value is fetched from the database, if the value is not None, its
>     column type (as it would be indicated in cursor.description) is looked
>     up in outputmap, and the resulting callable object is called upon to
>     convert the fetched value...
> 
> The DB-API uses integer type codes in the description tuple, not strings.
> PEP 249 says:
> 
>     The type_code can be interpreted by comparing it to the Type Objects
>     specified in the section below.
> 
> Later on it says:
> 
>     The type_code must compare equal to one of Type Objects defined below.
> 
> What am I supposed to use as keys in my input and output maps?  Python
> strings (as Carsten's document suggests)?  Ints (implied by how type_codes
> are represeted in .description)?  Type Objects?  Is there a list somewhere
> of valid key values?  Any example usage?  I'm specifically interested in
> transparently representing dates and times using objects from Python's
> datetime module.
> 
> Thanks,
>