the code there doesn't seem to show anything that would result in any DELETEs emitted. a DELETE here would only occur if you deassociated a TestDevice and a TestPartition by removing from the TestDevice.partitions collection or setting a TestPartition.device to None, and I don't see that. All of the manipulations you're doing with part.partition_id have nothing to do with any of that, SQLAlchemy's relationships have no idea what you're doing with those, and overall it's a bad idea to mix the usage of "obj.foreign_key = <id>" along with direct manipulation of the relationship (where you say dev_part.device = ndev) together. SQLAlchemy's relationship management code knows nothing about any of those foreign key sets. See http://docs.sqlalchemy.org/en/rel_0_9/faq.html#i-set-the-foo-id-attribute-on-my-instance-to-7-but-the-foo-attribute-is-still-none-shouldn-t-it-have-loaded-foo-with-id-7.
On Jul 21, 2014, at 2:55 AM, Bala Ramakrishnan <bal...@gmail.com> wrote: > I had asked this question on Stack Overflow. The details are at this link: > > http://stackoverflow.com/questions/24836816/updating-a-few-children-in-one-to-many-relationship-deletes-all-rows-and-adds-ne > > The summary is I have a parent class A and a bidirectional one-to-many > relationship with class B. When I update the class B list for an instance of > A, the update may involve deleting some class B instances, updating some of > them, and adding new ones. However, I find that SqlAlchemy deletes all ROWS > of classB, and the inserts the necessary new rows. I would have expected > SqlAchemy to insert only new rows, not delete and add those rows that are > being updated. Do you know what is wrong with my code? > > Thanks. > > > -- > 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 http://groups.google.com/group/sqlalchemy. > For more options, visit https://groups.google.com/d/optout. -- 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 http://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/d/optout.
