> from pylons import config as pylons_config

> On Jun 9, 10:52 am, Mike Driscoll <kyoso...@gmail.com> wrote:

> > By popular request, I'm sticking what I did on here:

> > I used the pylons docs to figure out part of this:http://www.pylonshq.com/docs/en/0.9.7/models/#multiple-engines

> > Here are the files to change:

> > #--------------
> > # development.ini

> > # create 2 or more sqlalchemy urls

> > sqlalchemy.main.url = sqlite:///%(here)s/devdata.db
> > sqlalchemy.other.url = sqlite:///%(here)s/devdata2.db

> > # -------------------------------------------

> > #--------------
> > # app_cfg.py (which is in the config folder)

> > # need to subclass AppConfig and
> > # override setup_sqlalchemy

> > from sqlalchemy import engine_from_config
> > from pyretention.model import init_model

> > class MyAppConfig(AppConfig):
> >     def setup_sqlalchemy(self):
> >         """Setup SQLAlchemy database engine."""
> >         engineOne = engine_from_config(pylons_config,
> > 'sqlalchemy.main.')
> >         engineTwo = engine_from_config(pylons_config,
> > 'sqlalchemy.other.')
> >         config['pylons.app_globals'].engineOne  = engineOne
> >         config['pylons.app_globals'].engineTwo  = engineTwo
> >         # Pass the engine to initmodel, to be able to introspect
> > tables
> >         init_model(engineOne, engineTwo)

> > base_config = MyAppConfig()

> > # -------------------------------------------

> > #--------------
> > # model\__init__.py

> > # Global session manager: DBSession() returns the Thread-local
> > # session object appropriate for the current web request.
> > maker = sessionmaker(autoflush=True, autocommit=False,
> >                      extension=ZopeTransactionExtension())
> > DBSession = scoped_session(maker)

> > maker2 = sessionmaker(autoflush=True, autocommit=False,
> >                       extension=ZopeTransactionExtension())
> > secondSession = scoped_session(maker2)

> > def init_model(engineOne, engineTwo):
> >     """Call me before using any of the tables or classes in the
> > model."""

> >     DBSession.configure(bind=engineTwo)

> >     secondSession.configure(bind=engineOne)

> >     # you only need this metadata
> >     #if you want to autoload a table
> >     second_metadata = MetaData(engineOne)
> > # -------------------------------------------

> > Note that in websetup, there is a call to

> > model.metadata.create_all(bind=config['pylons.app_globals'].sa_engine)

> > So when you override AppConfig in app_cfg.py, you'll want to change
> > one of these lines or hack websetup.py and any other references to
> > sa_engine:

> > config['pylons.app_globals'].engineOne = engineOne
> > config['pylons.app_globals'].engineTwo = engineTwo

> > to

> > config['pylons.app_globals'].sa_engine = engineOne

> > Hope that helps others.

> > - Mike

> > On Jun 9, 9:10 am, Mike Driscoll <kyoso...@gmail.com> wrote:

> > > For the record, this was resolved. I didn't know how to set up the
> > > second session object.

> > > Thanks!

> > > Mike

> > > On Jun 5, 2:06 pm, percious <ch...@percious.com> wrote:

> > > > It's not too bad, but you have to do your own custom app setup, and
> > > > modify your init_model stuff to create multiple transaction manager.

> > > > app_cfg.py:

> > > > from webapp.model import init_model
> > > > from sqlalchemy import engine_from_config
> > > > from tg.configuration import AppConfig, Bunch
> > > > from pylons import config as pylons_config

> > > > class MyAppConfig(AppConfig):
> > > >     def setup_sqlalchemy(self):
> > > >         """Setup SQLAlchemy database engine"""
> > > >         users_engine = engine_from_config(pylons_config,
> > > > 'sqlalchemy_users.')
> > > >         samples_engine = engine_from_config(pylons_config,
> > > > 'sqlalchemy_samples.')
> > > >         config['pylons.app_globals'].sa_engine = users_engine
> > > >         config['pylons.app_globals'].sa_users_engine = users_engine
> > > >         config['pylons.app_globals'].sa_samples_engine =
> > > > samples_engine

> > > >         # Pass the engine to initmodel, to be able to introspect
> > > > tables
> > > >         init_model(users_engine, samples_engine)

> > > > base_config = MyAppConfig()
> > > > ...

> > > > model/__init__.py:

> > > > import model.users
> > > > import model.samples

> > > > from model.users.mappers import *
> > > > from model.samples.mappers import *

> > > > from zope.sqlalchemy import ZopeTransactionExtension
> > > > from sqlalchemy.orm import scoped_session, sessionmaker

> > > > # Global session manager.  DBSession() returns the session object
> > > > # appropriate for the current web request.
> > > > maker = sessionmaker(autoflush=True, autocommit=False,
> > > >                      extension=ZopeTransactionExtension())

> > > > DBSession = UsersDBSession = scoped_session(maker)
> > > > maker3 = sessionmaker(autoflush=True, autocommit=False,
> > > >                      extension=ZopeTransactionExtension())

> > > > SamplesDBSession = scoped_session(maker3)
> > > > from model.users.metadata import metadata as users_metadata
> > > > from model.samples.metadata import metadata as samples_metadata

> > > > def init_model(users_engine, samples_engine):
> > > >     """Call me before using any of the tables or classes in the
> > > > model."""

> > > >     global UsersDBSession, SamplesDBSession, users_metadata,
> > > > samples_metadata

> > > >     UsersDBSession.configure(bind=users_engine)
> > > >     SamplesDBSession.configure(bind=samples_engine)

> > > >     users_metadata.bind = users_engine
> > > >     samples_metadata.bind = samples_engine

> > > > This is sort of an off-the cuff answer, we will provide a better one
> > > > in the next documentation release.

> > > > Come find me on IRC if you need some more help.

> > > > cheers.
> > > > -chris

> > > > On Jun 4, 10:31 am, Mike Driscoll <kyoso...@gmail.com> wrote:

> > > > > Hi,

> > > > > According to Mark Ramm's blog, supporting multiple databases is
> > > > > supposed to be easy (seehttp://compoundthinking.com/blog/index.php/2008/07/31/10-reasons-why-...).
> > > > > So where is the documentation that says how to do it??

> > > > > I "think" I need to put multiple sqlalchemy.url's in my
> > > > > development.ini file. But where oh where do I set up the SA engines
> > > > > at? The model's __init__ claims to support multiple databases too
> > > > > using MetaData, but it doesn't show where to bind the engine unless
> > > > > you're supposed to use the undocumented init_model function somehow.

> > > > > I'm pretty sure the init_model came from Perkins. Maybe he can tell me
> > > > > where to put my call to the function and how to set it up for multiple
> > > > > databases?

> > > > > That would be great!

> > > > > Thanks,

> > > > > Mike

> > > > > On May 28, 12:47 pm, Mike Driscoll <kyoso...@gmail.com> wrote:

> > > > > > Hi,

> > > > > > I am having a little trouble wrapping my head around how to configure
> > > > > > my model's __init__.py file for multiple databases. I am working on an
> > > > > > application that accesses 3 databases and does reflection on select
> > > > > > tables from all three.

> > > > > > I assume I need to comment out this line:

> > > > > > metadata = DeclarativeBase.metadata

> > > > > > and instead create three metadata instances based on MetaData(),
> > > > > > correct?

> > > > > > Finally, as I understand it, I can use the "init_model" function to do
> > > > > > the mapping for some of them, but I am not understanding where to
> > > > > > create the engine object to pass to it. Also, once I have my tables
> > > > > > mapped in the function, what do I put in my real model file if
> > > > > > anything?

> > > > > > Hopefully that stuff makes sense. I am using Python 2.5 and TG2 in a
> > > > > > virtualenv on Windows XP.

> > > > > > Thanks!

> > > > > > Mike