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