On Monday, May 29, 2017 at 12:27:51 PM UTC-4, Mike Bayer wrote: > > I'm assuming this "invalidates the transaction" is on the Postgresql > side, e.g. you get "current transaction is aborted". There is a simple > solution for that which is to use a savepoint, which with the ORM is via > session.begin_nested(). > > > http://docs.sqlalchemy.org/en/latest/orm/session_transaction.html#session-begin-nested > >
Ah, right, SAVEPOINT. Thanks, that's perfect. Just a follow up regarding the behavior. The docs provide the following example: Session = sessionmaker() session = Session() session.add(u1) session.add(u2) session.begin_nested() # establish a savepoint session.add(u3) session.rollback() # rolls back u3, keeps u1 and u2 session.commit() # commits u1 and u2 It also says each use of begin_nested() must have a corresponding commit() or rollback(). I got that the rollback in the example only rolls back to the last savepoint (begin_nested()), but what would a commit right after session.add(u3) do? It looks like the non-error case would look like this: Session = sessionmaker() session = Session() session.add(u1) session.add(u2) session.begin_nested() # establish a savepoint session.add(u3) session.commit() # ??? session.commit() # ??? what does each commit actually do? -- 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.
