On 7/3/14, 5:45 PM, Paul Molodowitch wrote: > I noticed that sqlalchemy now properly sets the onpudate / ondelete > properties of foreign keys when reflecting tables: > > https://bitbucket.org/zzzeek/sqlalchemy/issue/2183/support-on-delete-update-in-foreign-key > > However, it doesn't seem to set the cascade properties of > relationships to reflect these properties. ie, if the Child table > references the Parent table with a foreign key that has "ON DELETE > CASCADE", and the reference column does not allow NULL, when you > delete a parent table that has children, you will get an error, > because sqlalchemy will try to set the child's ref to NULL. > > ideally we should add "delete" in the relationship's cascade > properties (and probably delete-orphan as well), and then set > passive_updates=True. > > Or am I missing something obvious / doing something wrong / etc?
the configuration of a Column or ForeignKey has never been directly linked to how relationship() gets configured. passive_updates in particular is a thorny one as not every database supports ON UPDATE CASCADE, but for that matter not every database even supports ON DELETE CASCADE. There's also lots of variants to ON UPDATE and ON DELETE and SQLAlchemy has no awareness of any of these directly. If we were to explore some automatic configuration of relationship based on these attributes of ForeignKey, it would take place within the automap extension: see http://docs.sqlalchemy.org/en/rel_0_9/orm/extensions/automap.html. There are also recipes such that both relationship() and ForeignKey() are generated at once, these are also good places for this kind of thing to happen. See https://bitbucket.org/zzzeek/pycon2014_atmcraft/src/a6d96575bc497ce0c952bb81db9c05d054c98bb5/atmcraft/model/meta/orm.py?at=master for an example of this, I still am thinking of a way recipes like this could also be integrated into SQLAlchemy, possibly as an enhancement to declarative. -- 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.
