On Mon, Jul 8, 2019, at 6:08 AM, Gunnar Þór Magnússon wrote: > Hello, > > Some legacy code at work that I don't fully understand (and whose authors are > all long gone) does the following to eventually insert some values into the > table it gets: > > meta = sqlalchemy.MetaData(bind=session.get_bind()) > meta.reflect() > table = sqlalchemy.Table(TableName.__tablename__, meta, autoload=True) > > The meta.reflect() call fails if the session comes from a sessionmaker bound > to a copy of an engine that has a non-default isolation level, for example: > > engine = sqlalchemy.create_engine(setup) > maker = > sqlalchemy.orm.sessionmaker(bind=engine.execution_options(isolation_level='SERIALIZABLE')) > session = maker() > > The error message it gives is "AttributeError: 'OptionEngine' object has no > attribute 'engine'". The reason seems to be that in this case, > session.get_bind() returns an OptionEngine, which seems to be a facade around > the original Engine; it proxies to the original one.
oh that definitely would be a bug. > > See below for a minimal complete example [A] with a Conda environment [B]. > > I can get around this by checking whether the get_bind() call gives me an > OptionEngine, and pull the proxied Engine out of the object if it does, but > that involves using internal SQLAlchemy object variables and might break in > the future. > > 1. Should what I'm doing here work at all? That is, should OptionEngine > define 'engine' and have it resolve to whatever original Engine it was > created from? > > 2. If not, and what I've inherited is horrifying, does anyone have ideas on > how to make it better? The only comments around this piece of code say they > do this dance to be able to insert values into columns that are in the DB > table but not the SQLAlchemy ORM table. you have a workaround in place now right? I will commit a fix for this today https://github.com/sqlalchemy/sqlalchemy/issues/4754 > > Thank you, > Gunnar > > [A] Minimal example (done here in sqlite3, also works on SQL Server): > > import sqlalchemy > import sqlalchemy.orm > import sqlalchemy.ext.declarative > > Base = sqlalchemy.ext.declarative.declarative_base() > > class Foo(Base): > __tablename__ = 'foos' > id = sqlalchemy.Column(sqlalchemy.Integer, primary_key=True) > val = sqlalchemy.Column(sqlalchemy.Integer) > > if __name__ == '__main__': > db = sqlalchemy.create_engine('sqlite:///') > Foo.metadata.create_all(db) > > maker = > sqlalchemy.orm.sessionmaker(bind=db.execution_options(isolation_level='SERIALIZABLE')) > session = maker() > > bind = session.get_bind() > meta = sqlalchemy.MetaData(bind=bind) > meta.reflect() > table = sqlalchemy.Table(Foo.__tablename__, meta, autoload=True) > > vals = list(range(100)) > ins = table.insert().values(vals) > session.execute(ins) > session.commit() > session.close() > > [B] Conda environment that reproduces the problem in the example: > > # Name Version Build Channel > _libgcc_mutex 0.1 main > ca-certificates 2019.5.15 0 > certifi 2019.6.16 py37_0 > libedit 3.1.20181209 hc058e9b_0 > libffi 3.2.1 hd88cf55_4 > libgcc-ng 9.1.0 hdf63c60_0 > libstdcxx-ng 9.1.0 hdf63c60_0 > ncurses 6.1 he6710b0_1 > openssl 1.1.1c h7b6447c_1 > pip 19.1.1 py37_0 > python 3.7.3 h0371630_0 > readline 7.0 h7b6447c_5 > setuptools 41.0.1 py37_0 > sqlalchemy 1.3.5 py37h7b6447c_0 > sqlite 3.28.0 h7b6447c_0 > tk 8.6.8 hbc83047_0 > wheel 0.33.4 py37_0 > xz 5.2.4 h14c3975_4 > zlib 1.2.11 h7b6447c_3 > > > > -- > 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. > To view this discussion on the web visit > https://groups.google.com/d/msgid/sqlalchemy/d81b41c0-5e38-4601-a487-c763d3896b91%40googlegroups.com > > <https://groups.google.com/d/msgid/sqlalchemy/d81b41c0-5e38-4601-a487-c763d3896b91%40googlegroups.com?utm_medium=email&utm_source=footer>. > For more options, visit https://groups.google.com/d/optout. -- 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. To view this discussion on the web visit https://groups.google.com/d/msgid/sqlalchemy/c4c6746b-b900-4ba1-b71d-ecf9bf4f89ad%40www.fastmail.com. For more options, visit https://groups.google.com/d/optout.
