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# mssql/pymssql.py
# Copyright (C) 2005-2011 the SQLAlchemy authors and contributors <see AUTHORS file>
#
# This module is part of SQLAlchemy and is released under
# the MIT License: http://www.opensource.org/licenses/mit-license.php
"""
Support for the pymssql dialect.
This dialect supports pymssql 1.0 and greater.
pymssql is available at:
http://pymssql.sourceforge.net/
Connecting
^^^^^^^^^^
Sample connect string::
mssql+pymssql://<username>:<password>@<freetds_name>
Adding "?charset=utf8" or similar will cause pymssql to return
strings as Python unicode objects. This can potentially improve
performance in some scenarios as decoding of strings is
handled natively.
Limitations
^^^^^^^^^^^
pymssql inherits a lot of limitations from FreeTDS, including:
* no support for multibyte schema identifiers
* poor support for large decimals
* poor support for binary fields
* poor support for VARCHAR/CHAR fields over 255 characters
Please consult the pymssql documentation for further information.
"""
from sqlalchemy.dialects.mssql.base import MSDialect
from sqlalchemy import types as sqltypes, util, processors
import re
class _MSNumeric_pymssql(sqltypes.Numeric):
def result_processor(self, dialect, type_):
if not self.asdecimal:
return processors.to_float
else:
return sqltypes.Numeric.result_processor(self, dialect, type_)
class MSDialect_pymssql(MSDialect):
supports_sane_rowcount = False
max_identifier_length = 30
driver = 'pymssql'
colspecs = util.update_copy(
MSDialect.colspecs,
{
sqltypes.Numeric:_MSNumeric_pymssql,
sqltypes.Float:sqltypes.Float,
}
)
@classmethod
def dbapi(cls):
module = __import__('pymssql')
# pymmsql doesn't have a Binary method. we use string
# TODO: monkeypatching here is less than ideal
module.Binary = str
client_ver = tuple(int(x) for x in module.__version__.split("."))
if client_ver < (1, ):
util.warn("The pymssql dialect expects at least "
"the 1.0 series of the pymssql DBAPI.")
return module
def __init__(self, **params):
super(MSDialect_pymssql, self).__init__(**params)
self.use_scope_identity = True
def _get_server_version_info(self, connection):
vers = connection.scalar("select @@version")
m = re.match(
r"Microsoft SQL Server.*? - (\d+).(\d+).(\d+).(\d+)", vers)
if m:
return tuple(int(x) for x in m.group(1, 2, 3, 4))
else:
return None
def create_connect_args(self, url):
opts = url.translate_connect_args(username='user')
opts.update(url.query)
port = opts.pop('port', None)
if port and 'host' in opts:
opts['host'] = "%s:%s" % (opts['host'], port)
return [[], opts]
def is_disconnect(self, e, connection, cursor):
for msg in (
"Error 10054",
"Not connected to any MS SQL server",
"Connection is closed"
):
if msg in str(e):
return True
else:
return False
dialect = MSDialect_pymssql
|
