mirror of
https://github.com/janeczku/calibre-web
synced 2024-11-09 19:40:00 +00:00
255 lines
9.0 KiB
Python
255 lines
9.0 KiB
Python
# mssql/pyodbc.py
|
|
# Copyright (C) 2005-2013 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
|
|
|
|
"""
|
|
.. dialect:: mssql+pyodbc
|
|
:name: PyODBC
|
|
:dbapi: pyodbc
|
|
:connectstring: mssql+pyodbc://<username>:<password>@<dsnname>
|
|
:url: http://pypi.python.org/pypi/pyodbc/
|
|
|
|
Additional Connection Examples
|
|
-------------------------------
|
|
|
|
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
|
|
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 which includes the port
|
|
information using the comma syntax. 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 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
|
|
|
|
* ``mssql+pyodbc://user:pass@host/db?driver=MyDriver`` - connects using a connection
|
|
string that includes a custom
|
|
ODBC driver name. This will create the following connection string::
|
|
|
|
DRIVER={MyDriver};Server=host;Database=db;UID=user;PWD=pass
|
|
|
|
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'
|
|
|
|
Unicode Binds
|
|
-------------
|
|
|
|
The current state of PyODBC on a unix backend with FreeTDS and/or
|
|
EasySoft is poor regarding unicode; different OS platforms and versions of UnixODBC
|
|
versus IODBC versus FreeTDS/EasySoft versus PyODBC itself dramatically
|
|
alter how strings are received. The PyODBC dialect attempts to use all the information
|
|
it knows to determine whether or not a Python unicode literal can be
|
|
passed directly to the PyODBC driver or not; while SQLAlchemy can encode
|
|
these to bytestrings first, some users have reported that PyODBC mis-handles
|
|
bytestrings for certain encodings and requires a Python unicode object,
|
|
while the author has observed widespread cases where a Python unicode
|
|
is completely misinterpreted by PyODBC, particularly when dealing with
|
|
the information schema tables used in table reflection, and the value
|
|
must first be encoded to a bytestring.
|
|
|
|
It is for this reason that whether or not unicode literals for bound
|
|
parameters be sent to PyODBC can be controlled using the
|
|
``supports_unicode_binds`` parameter to ``create_engine()``. When
|
|
left at its default of ``None``, the PyODBC dialect will use its
|
|
best guess as to whether or not the driver deals with unicode literals
|
|
well. When ``False``, unicode literals will be encoded first, and when
|
|
``True`` unicode literals will be passed straight through. This is an interim
|
|
flag that hopefully should not be needed when the unicode situation stabilizes
|
|
for unix + PyODBC.
|
|
|
|
.. versionadded:: 0.7.7
|
|
``supports_unicode_binds`` parameter to ``create_engine()``\ .
|
|
|
|
"""
|
|
|
|
from .base import MSExecutionContext, MSDialect
|
|
from ...connectors.pyodbc import PyODBCConnector
|
|
from ... import types as sqltypes, util
|
|
import decimal
|
|
|
|
|
|
class _MSNumeric_pyodbc(sqltypes.Numeric):
|
|
"""Turns Decimals with adjusted() < 0 or > 7 into strings.
|
|
|
|
The routines here are needed for older pyodbc versions
|
|
as well as current mxODBC versions.
|
|
|
|
"""
|
|
|
|
def bind_processor(self, dialect):
|
|
|
|
super_process = super(_MSNumeric_pyodbc, self).\
|
|
bind_processor(dialect)
|
|
|
|
if not dialect._need_decimal_fix:
|
|
return super_process
|
|
|
|
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
|
|
|
|
# these routines needed for older versions of pyodbc.
|
|
# as of 2.1.8 this logic is integrated.
|
|
|
|
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.as_tuple()[1]]))
|
|
|
|
def _large_dec_to_string(self, value):
|
|
_int = value.as_tuple()[1]
|
|
if 'E' in str(value):
|
|
result = "%s%s%s" % (
|
|
(value < 0 and '-' or ''),
|
|
"".join([str(s) for s in _int]),
|
|
"0" * (value.adjusted() - (len(_int) - 1)))
|
|
else:
|
|
if (len(_int) - 1) > value.adjusted():
|
|
result = "%s%s.%s" % (
|
|
(value < 0 and '-' or ''),
|
|
"".join(
|
|
[str(s) for s in _int][0:value.adjusted() + 1]),
|
|
"".join(
|
|
[str(s) for s in _int][value.adjusted() + 1:]))
|
|
else:
|
|
result = "%s%s" % (
|
|
(value < 0 and '-' or ''),
|
|
"".join(
|
|
[str(s) for s in _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=None, **params):
|
|
super(MSDialect_pyodbc, self).__init__(**params)
|
|
self.description_encoding = description_encoding
|
|
self.use_scope_identity = self.use_scope_identity and \
|
|
self.dbapi and \
|
|
hasattr(self.dbapi.Cursor, 'nextset')
|
|
self._need_decimal_fix = self.dbapi and \
|
|
self._dbapi_version() < (2, 1, 8)
|
|
|
|
dialect = MSDialect_pyodbc
|