I've updated the documentation and in a few hours it should be up at https://docs.sqlalchemy.org/en/latest/orm/persistence_techniques.html#simple-vertical-partitioning On Tue, Nov 6, 2018 at 3:04 PM <yoch.me...@gmail.com> wrote: > > Oh, it's perfect for me if I can use bases for bindings. > > Thank you > > Le mardi 6 novembre 2018 21:27:19 UTC+2, Mike Bayer a écrit : >> >> On Tue, Nov 6, 2018 at 2:20 PM <yoch....@gmail.com> wrote: >> > >> > I have many classes, so it's seems a better idea to use something like >> > that (but I don't know what exactly is this registry, and why it's a >> > WeakRef dict) : >> > >> > binding = {cls: engine for cls in Base._decl_class_registry.values()} >> >> >> see I don't want you to use that because it's a private variable. You >> should make your own "registry" as you do the automap. >> >> >> > >> > If not, maybe I can use the second approach, overloading Session, but is >> > this safe ? >> > >> > class BindSession(Session): >> > def get_bind(self, mapper=None, clause=None): >> > if mapper: >> > if issubclass(mapper.class_, SomeBase): >> > return some_engine >> > elif issubclass(mapper.class_, OtherBase): >> > return other_engine >> >> oh is it based on two different bases? Guess what, you can use those >> base classes: >> >> session = Session(binds={SomeBase: engine1, OtherBase: engine2}) >> >> docs seem to not be in-depth enough or adequately cross-linked, will fix >> >> >> >> > # correct ? >> > return super().get_bind(mapper,clause) >> > >> > >> > >> > >> > >> > >> > >> > >> > Le mardi 6 novembre 2018 18:07:48 UTC+2, Mike Bayer a écrit : >> >> >> >> On Tue, Nov 6, 2018 at 9:41 AM <yoch....@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/ >> >> > >> >> > To post example code, please provide an MCVE: Minimal, Complete, and >> >> > Verifiable Example. 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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 Example. See http://stackoverflow.com/help/mcve for a full description. --- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To unsubscribe from this group and stop receiving emails from it, send an email to sqlalchemy+unsubscr...@googlegroups.com. To post to this group, send email to sqlalchemy@googlegroups.com. Visit this group at https://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/d/optout.
