On Oct 29, 8:44 pm, "Michael Bayer" <mike...@zzzcomputing.com> wrote: > Tvrtko wrote: > > > Hi, > > > is it possible to merge an object back to session, but without merging > > the entire tree of related objects. Just this one root object. > > the general way is to disable merge cascade on the relation(), using > "cascade='save-update'" or "cascade=None"
I still didn't try "cascade" options, but the object copy works. > > I created a new user instance and copied all relevant attributes to > > it. I then tried to merge this copy back to session, but it doesn't > > work because you can only merge detached objects not transient ones > > transient objects can be merged. They get added to the session and enter > the pending state. I get: InvalidRequestError: merge() with dont_load=True option does not support objects transient (i.e. unpersisted) objects. flush() all changes on mapped instances before merging with dont_load=True. I managed to make a copy for merge like this: obj = User() obj.user_id = user.user_id obj.name = user.name obj._instance_key = user.user_id obj._state.modified = False user = session.merge(obj, dont_load=True) I guess I can now try the cascade option. > > > I then tried removing related objects but I'm not even sure how to do > > that. Anyway, the problem here is that you can't merge dirty objects. > > dirty objects are also mergeable, but only if you allow the Session to > load their existing state from the database (i.e. you dont use the > 'dont_load' flag). If you're playing with caching you shouldn't put > dirty objects into a cache. I need dont_load otherwise my caching isn't really caching. > > > My version of sqlalchemy is 0.4.4 > > oof. go to 0.4.8 at the very least. 0.5.6 preferably. In the past, I would often have to spend days porting from one version to another (0.2->0.3->0.4) because of some subtle changes in sqlalchemy (sessions, threading, way of accessing properties, mappers...). This would be just 0.4.x->0.4.y but I'm still reluctant. --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To post to this group, send email to sqlalchemy@googlegroups.com To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~----------~----~----~----~------~----~------~--~---
