Michael Bayer wrote: > sqlalchemy objects always log change events when things are modified. > when i need a "throwaway" version of an object I often use a separate > class for that, sometimes just a vanilla "object" subclass that I set > attributes on, i.e. > > > class Lightweight(object): > def __init__(self, **kw): > self.__dict__.update(kw) > > @property > def lightweight(self): > return Lightweight(id=self.id, name=self.name, > attr1=self.attr1.lightweight) > > the lightweight attribute above can be automated in different ways too so > that individual versions of the method aren't needed.
Hmm thanks for the thought, that's interesting option - though forgive me for being slow, but how do you save such a 'throwaway' between http requests? Bc you can't save it in SQLA, or can you? In a blob directly in db? pickle/unpickle temporary file? Regards, mk > 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 -~----------~----~----~----~------~----~------~--~---
