On Tue, Nov 6, 2018 at 9:41 AM <yoch.me...@gmail.com> wrote:
>
> Hi,
>
> I'm using a schema with multiple DB, like :
>
> engine1 = create_engine("mysql://localhost/{db}?charset=utf8".format(db=db1))
> engine2 = create_engine("mysql://localhost/{db}?charset=utf8".format(db=db2))
>
> Then I use automap and reflection to generate mapping of all classes needed.
>
> Sometime, I want to use classes from both databases, but I cannot bind my
> session directly with two engines.
>
> I noticed that I can use the Session `binds` argument to decide which class
> to bind to some engine, but I have many classes to include here, and this is
> somewhat error prone.
>
> Is there any solution to automate the binding definition against each class ?
> Or to bind a session directly to multiple engines ?
you would use the "binds" argument as you saw in
https://docs.sqlalchemy.org/en/latest/orm/session_api.html#sqlalchemy.orm.session.Session.params.binds.
as you noticed though, you have to tell the Session which classes map
to which engine. So when you use automap, each time you reflect()
for a particular engine, you need to gather all the classes that were
generated for that call and add them to a dictionary, which you can
then pass to session.binds.
If you have some totally other way to tell the Session, given a class,
which engine to use, you can also make your own method to do whatever
you want and override it, by overriding get_bind:
https://docs.sqlalchemy.org/en/latest/orm/session_api.html#sqlalchemy.orm.session.Session.get_bind
. you probably don't need to do it this way but there's an example
of how that looks at
http://techspot.zzzeek.org/2012/01/11/django-style-database-routers-in-sqlalchemy/.
>
> Thank you
>
>
> --
> SQLAlchemy -
> The Python SQL Toolkit and Object Relational Mapper
>
> http://www.sqlalchemy.org/
>
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SQLAlchemy -
The Python SQL Toolkit and Object Relational Mapper
http://www.sqlalchemy.org/
To post example code, please provide an MCVE: Minimal, Complete, and Verifiable
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