Hello az, thanks for answer,
a...@svilendobrev.com wrote: > the copy can be a dummy non-db-aware - if that is ok in your case > > there's yet another option; u can just go all over the original > object, and on cancel do a rollback, and restore all changed stuff > back by hand (eventualy looking at object-state's history). But this > assumes short editing/single user. > > if the editing session is really long, u need a "user transaction", > that is a copy saved to the db etc. then later at ok, retrieved, > removed and replacing the original object (or upgrading if u have > versions). > > m2m relations are ok for copying; but they have caused me some > leftovers when creating new objects then destroying them without > save. > > one2many are the tricky ones - there's no "copy" as semantics, > there's "move". Say again? I can't (shallow) copy one-to-many object to another? Or do you mean: I can't copy it to another object, modify it and then copy it back? > AFAIK there's no a perfect solution for all cases; u have to decide > which one is the least painful for your setup. I think I'll go with the 'generic temporary object' method proposed by Mike, I just need to figure out the best way to save that object between http requests. Regards, mk > > > On Wednesday 06 May 2009 18:00:33 Marcin Krol wrote: >> a...@svilendobrev.com wrote: >>> u'd better edit a new copy and on save copy all back into >>> original then commit that one, on cancel abandon the new one (but >>> beware of m2m relations if u have them). >>> all else isn't safe/nice IMO. >> To make it specific, should I do smth like: >> >> 1. on beginning of edit, make a new instance of an object, then >> copy all the attributes from the original object, save the 'under >> editing' object >> >> 2. on user save, copy all the attributes from the 'under editing' >> object one by one into the original object, expunge the 'under >> editing' object, do session.save()? >> >> I'm not even sure this would be safe, as I indeed have many to many >> relation, Reservation having many Hosts, with hosts being >> added/removed in Reservation. >> >> So I would be moving or copying the Hosts collection from one >> Reservation object to another Reservation object and back -- Mike, >> is this safe? >> >> Regards, >> mk >> >>> On Wednesday 06 May 2009 17:25:47 Marcin Krol wrote: >>>> Hello, >>>> >>>> I would like to implement typical Save / Cancel dialog operating >>>> on normal SQLA objects. >>>> >>>> For that purpose, the most convenient way is to make a shallow >>>> copy of an object using copy.copy(obj), let the user edit this >>>> object, and on user pressing OK in dialog replace it in SQLA, >>>> e.g. expunge existing object and add the edited object as >>>> replacement (and obviously drop the edited copy of object if >>>> user pressed Cancel instead). >>>> >>>> The reason I'm trying to do this instead of just doing >>>> session.commit() or session.close() on the changed object is >>>> that editing in my app is pretty complicated and it is done >>>> across many http requests, so I obviously need to save the state >>>> of the object in between them. >>>> >>>> Are there any problems with such approach? Risks? Is this safe? >>>> >>>> There obviously have to be some issues, such as enforcing the >>>> same PK in a new obj as in the old object, which is the first >>>> issue that comes to my mind. >>>> >>>> >>>> Regards, >>>> mk >> > > > > > --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
