""" Support for MS-SQL via pyodbc. pyodbc is available at: http://pypi.python.org/pypi/pyodbc/ Connecting ^^^^^^^^^^ Examples of pyodbc connection string URLs: * ``mssql+pyodbc://mydsn`` - connects using the specified DSN named ``mydsn``. The connection string that is created will appear like:: dsn=mydsn;Trusted_Connection=Yes * ``mssql+pyodbc://user:pass@mydsn`` - connects using the DSN named ``mydsn`` passing in the ``UID`` and ``PWD`` information. The connection string that is created will appear like:: dsn=mydsn;UID=user;PWD=pass * ``mssql+pyodbc://user:pass@mydsn/?LANGUAGE=us_english`` - connects using the DSN named ``mydsn`` passing in the ``UID`` and ``PWD`` information, plus the additional connection configuration option ``LANGUAGE``. The connection string that is created will appear like:: dsn=mydsn;UID=user;PWD=pass;LANGUAGE=us_english * ``mssql+pyodbc://user:pass@host/db`` - connects using a connection string dynamically created that would appear like:: DRIVER={SQL Server};Server=host;Database=db;UID=user;PWD=pass * ``mssql+pyodbc://user:pass@host:123/db`` - connects using a connection string that is dynamically created, which also includes the port information using the comma syntax. If your connection string requires the port information to be passed as a ``port`` keyword see the next example. This will create the following connection string:: DRIVER={SQL Server};Server=host,123;Database=db;UID=user;PWD=pass * ``mssql+pyodbc://user:pass@host/db?port=123`` - connects using a connection string that is dynamically created that includes the port information as a separate ``port`` keyword. This will create the following connection string:: DRIVER={SQL Server};Server=host;Database=db;UID=user;PWD=pass;port=123 If you require a connection string that is outside the options presented above, use the ``odbc_connect`` keyword to pass in a urlencoded connection string. What gets passed in will be urldecoded and passed directly. For example:: mssql+pyodbc:///?odbc_connect=dsn%3Dmydsn%3BDatabase%3Ddb would create the following connection string:: dsn=mydsn;Database=db Encoding your connection string can be easily accomplished through the python shell. For example:: >>> import urllib >>> urllib.quote_plus('dsn=mydsn;Database=db') 'dsn%3Dmydsn%3BDatabase%3Ddb' """ from sqlalchemy.dialects.mssql.base import MSExecutionContext, MSDialect from sqlalchemy.connectors.pyodbc import PyODBCConnector from sqlalchemy import types as sqltypes, util import decimal class _MSNumeric_pyodbc(sqltypes.Numeric): """Turns Decimals with adjusted() < 0 or > 7 into strings. This is the only method that is proven to work with Pyodbc+MSSQL without crashing (floats can be used but seem to cause sporadic crashes). """ def bind_processor(self, dialect): super_process = super(_MSNumeric_pyodbc, self).bind_processor(dialect) def process(value): if self.asdecimal and \ isinstance(value, decimal.Decimal): adjusted = value.adjusted() if adjusted < 0: return self._small_dec_to_string(value) elif adjusted > 7: return self._large_dec_to_string(value) if super_process: return super_process(value) else: return value return process def _small_dec_to_string(self, value): return "%s0.%s%s" % ( (value < 0 and '-' or ''), '0' * (abs(value.adjusted()) - 1), "".join([str(nint) for nint in value._int])) def _large_dec_to_string(self, value): if 'E' in str(value): result = "%s%s%s" % ( (value < 0 and '-' or ''), "".join([str(s) for s in value._int]), "0" * (value.adjusted() - (len(value._int)-1))) else: if (len(value._int) - 1) > value.adjusted(): result = "%s%s.%s" % ( (value < 0 and '-' or ''), "".join([str(s) for s in value._int][0:value.adjusted() + 1]), "".join([str(s) for s in value._int][value.adjusted() + 1:])) else: result = "%s%s" % ( (value < 0 and '-' or ''), "".join([str(s) for s in value._int][0:value.adjusted() + 1])) return result class MSExecutionContext_pyodbc(MSExecutionContext): _embedded_scope_identity = False def pre_exec(self): """where appropriate, issue "select scope_identity()" in the same statement. Background on why "scope_identity()" is preferable to "@@identity": http://msdn.microsoft.com/en-us/library/ms190315.aspx Background on why we attempt to embed "scope_identity()" into the same statement as the INSERT: http://code.google.com/p/pyodbc/wiki/FAQs#How_do_I_retrieve_autogenerated/identity_values? """ super(MSExecutionContext_pyodbc, self).pre_exec() # don't embed the scope_identity select into an "INSERT .. DEFAULT VALUES" if self._select_lastrowid and \ self.dialect.use_scope_identity and \ len(self.parameters[0]): self._embedded_scope_identity = True self.statement += "; select scope_identity()" def post_exec(self): if self._embedded_scope_identity: # Fetch the last inserted id from the manipulated statement # We may have to skip over a number of result sets with no data (due to triggers, etc.) while True: try: # fetchall() ensures the cursor is consumed # without closing it (FreeTDS particularly) row = self.cursor.fetchall()[0] break except self.dialect.dbapi.Error, e: # no way around this - nextset() consumes the previous set # so we need to just keep flipping self.cursor.nextset() self._lastrowid = int(row[0]) else: super(MSExecutionContext_pyodbc, self).post_exec() class MSDialect_pyodbc(PyODBCConnector, MSDialect): execution_ctx_cls = MSExecutionContext_pyodbc pyodbc_driver_name = 'SQL Server' colspecs = util.update_copy( MSDialect.colspecs, { sqltypes.Numeric:_MSNumeric_pyodbc } ) def __init__(self, description_encoding='latin-1', **params): super(MSDialect_pyodbc, self).__init__(**params) self.description_encoding = description_encoding self.use_scope_identity = self.dbapi and hasattr(self.dbapi.Cursor, 'nextset') dialect = MSDialect_pyodbc