SqlAlchemy equivalent of pyodbc connect string using FreeTDS

Question

The following works:

import pyodbc pyodbc.connect('DRIVER={FreeTDS};Server=my.db.server;Database=mydb;UID=myuser;PWD=mypwd;TDS_Version=8.0;Port=1433;') 

The following fails:

import sqlalchemy sqlalchemy.create_engine("mssql://myuser:[email protected]:1433/mydb?driver=FreeTDS& odbc_options='TDS_Version=8.0'").connect() 

The error message for above is:

DBAPIError: (Error) ('08001', '[08001] [unixODBC][FreeTDS][SQL Server]Unable to connect to data source (0) (SQLDriverConnectW)') None None

Can someone please point me in the right direction? Is there a way I can simply tell sqlalchemy to pass a specific connect string through to pyodbc?

Please Note: I want to keep this DSN-less.

Answer 1

The example by @Singletoned would not work for me with SQLAlchemy 0.7.2. From the SQLAlchemy docs for connecting to SQL Server:

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.

So to make it work I used:

import urllib quoted = urllib.quote_plus('DRIVER={FreeTDS};Server=my.db.server;Database=mydb;UID=myuser;PWD=mypwd;TDS_Version=8.0;Port=1433;') sqlalchemy.create_engine('mssql+pyodbc:///?odbc_connect={}'.format(quoted)) 

This should apply to Sybase as well.

NOTE: In python 3 the urllib module has been split into parts and renamed. Thus, this line in python 2.7:

quoted = urllib.quote_plus 

has to be changed to this line in python3:

quoted = urllib.parse.quote_plus 

Answer 2

I'm still interested in a way to do this in one line within the sqlalchemy create_engine statement, but I found the following workaround detailed here:

import pyodbc, sqlalchemy  def connect():     pyodbc.connect('DRIVER={FreeTDS};Server=my.db.server;Database=mydb;UID=myuser;PWD=mypwd;TDS_Version=8.0;Port=1433;')  sqlalchemy.create_engine('mssql://', creator=connect) 

UPDATE: Addresses a concern I raised in my own comment about not being able to pass arguments to the connect string. The following is a general solution if you need to dynamically connect to different databases at runtime. I only pass the database name as a parameter, but additional parameters could easily be used as needed:

import pyodbc import os  class Creator:     def __init__(self, db_name='MyDB'):         """Initialization procedure to receive the database name"""         self.db_name = db_name      def __call__(self):         """Defines a custom creator to be passed to sqlalchemy.create_engine            http://stackoverflow.com/questions/111234/what-is-a-callable-in-python#111255"""         if os.name == 'posix':             return pyodbc.connect('DRIVER={FreeTDS};'                                   'Server=my.db.server;'                                   'Database=%s;'                                   'UID=myuser;'                                   'PWD=mypassword;'                                   'TDS_Version=8.0;'                                   'Port=1433;' % self.db_name)         elif os.name == 'nt':             # use development environment             return pyodbc.connect('DRIVER={SQL Server};'                                   'Server=127.0.0.1;'                                   'Database=%s_Dev;'                                   'UID=user;'                                   'PWD=;'                                   'Trusted_Connection=Yes;'                                   'Port=1433;' % self.db_name)  def en(db_name):     """Returns a sql_alchemy engine"""     return sqlalchemy.create_engine('mssql://', creator=Creator(db_name))