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1# mssql/pymssql.py
2# Copyright (C) 2005-2020 the SQLAlchemy authors and contributors
3# <see AUTHORS file>
4#
5# This module is part of SQLAlchemy and is released under
6# the MIT License: http://www.opensource.org/licenses/mit-license.php
8"""
9.. dialect:: mssql+pymssql
10 :name: pymssql
11 :dbapi: pymssql
12 :connectstring: mssql+pymssql://<username>:<password>@<freetds_name>/?charset=utf8
14pymssql is a Python module that provides a Python DBAPI interface around
15`FreeTDS <http://www.freetds.org/>`_.
17.. note::
19 pymssql is currently not included in SQLAlchemy's continuous integration
20 (CI) testing.
22Modern versions of this driver worked very well with SQL Server and FreeTDS
23from Linux and were highly recommended. However, pymssql is currently
24unmaintained and has fallen behind the progress of the Microsoft ODBC driver in
25its support for newer features of SQL Server. The latest official release of
26pymssql at the time of this document is version 2.1.4 (August, 2018) and it
27lacks support for:
291. table-valued parameters (TVPs),
302. ``datetimeoffset`` columns using timezone-aware ``datetime`` objects
31 (values are sent and retrieved as strings), and
323. encrypted connections (e.g., to Azure SQL), when pymssql is installed from
33 the pre-built wheels. Support for encrypted connections requires building
34 pymssql from source, which can be a nuisance, especially under Windows.
36The above features are all supported by mssql+pyodbc when using Microsoft's
37ODBC Driver for SQL Server (msodbcsql), which is now available for Windows,
38(several flavors of) Linux, and macOS.
41""" # noqa
42import re
44from .base import MSDialect
45from .base import MSIdentifierPreparer
46from ... import processors
47from ... import types as sqltypes
48from ... import util
51class _MSNumeric_pymssql(sqltypes.Numeric):
52 def result_processor(self, dialect, type_):
53 if not self.asdecimal:
54 return processors.to_float
55 else:
56 return sqltypes.Numeric.result_processor(self, dialect, type_)
59class MSIdentifierPreparer_pymssql(MSIdentifierPreparer):
60 def __init__(self, dialect):
61 super(MSIdentifierPreparer_pymssql, self).__init__(dialect)
62 # pymssql has the very unusual behavior that it uses pyformat
63 # yet does not require that percent signs be doubled
64 self._double_percents = False
67class MSDialect_pymssql(MSDialect):
68 supports_native_decimal = True
69 driver = "pymssql"
71 preparer = MSIdentifierPreparer_pymssql
73 colspecs = util.update_copy(
74 MSDialect.colspecs,
75 {sqltypes.Numeric: _MSNumeric_pymssql, sqltypes.Float: sqltypes.Float},
76 )
78 @classmethod
79 def dbapi(cls):
80 module = __import__("pymssql")
81 # pymmsql < 2.1.1 doesn't have a Binary method. we use string
82 client_ver = tuple(int(x) for x in module.__version__.split("."))
83 if client_ver < (2, 1, 1):
84 # TODO: monkeypatching here is less than ideal
85 module.Binary = lambda x: x if hasattr(x, "decode") else str(x)
87 if client_ver < (1,):
88 util.warn(
89 "The pymssql dialect expects at least "
90 "the 1.0 series of the pymssql DBAPI."
91 )
92 return module
94 def _get_server_version_info(self, connection):
95 vers = connection.scalar("select @@version")
96 m = re.match(r"Microsoft .*? - (\d+).(\d+).(\d+).(\d+)", vers)
97 if m:
98 return tuple(int(x) for x in m.group(1, 2, 3, 4))
99 else:
100 return None
102 def create_connect_args(self, url):
103 opts = url.translate_connect_args(username="user")
104 opts.update(url.query)
105 port = opts.pop("port", None)
106 if port and "host" in opts:
107 opts["host"] = "%s:%s" % (opts["host"], port)
108 return [[], opts]
110 def is_disconnect(self, e, connection, cursor):
111 for msg in (
112 "Adaptive Server connection timed out",
113 "Net-Lib error during Connection reset by peer",
114 "message 20003", # connection timeout
115 "Error 10054",
116 "Not connected to any MS SQL server",
117 "Connection is closed",
118 "message 20006", # Write to the server failed
119 "message 20017", # Unexpected EOF from the server
120 "message 20047", # DBPROCESS is dead or not enabled
121 ):
122 if msg in str(e):
123 return True
124 else:
125 return False
127 def set_isolation_level(self, connection, level):
128 if level == "AUTOCOMMIT":
129 connection.autocommit(True)
130 else:
131 connection.autocommit(False)
132 super(MSDialect_pymssql, self).set_isolation_level(
133 connection, level
134 )
137dialect = MSDialect_pymssql