On Jan 16, 2012, at 12:53 PM, Mariano Mara wrote: > On 05.01.12 16:13, Michael Bayer wrote: >> >> On Jan 5, 2012, at 3:03 PM, Mariano Mara wrote: >> >>> Hi there! I have a master-detail entity. Since I do some post-processing >>> work >>> on the details before inserting the entity in the db, I added an >>> 'after_insert' event where I do the extra stuff. >>> One of the things I need is to make sure certain "details" have been >>> selected by the user and in case he didn't I add some default values on his >>> behalf, just like >>> >>> master.detail.append(DetailCls(score=100, >>> timestamp=datetime.datetime.now())) >> >> don't do any kind of manipulation of the flush plan, which includes >> collection alterations, inside of after_insert(). >> >> The append() operation here is most cleanly implemented in the __init__ >> method of your Master object. That way the model itself handles the shape >> it should be in. >> >> Another way to set up state is using the @validates hook to respond to an >> attribute set event: >> >> http://www.sqlalchemy.org/docs/orm/mapper_config.html?highlight=validates#simple-validators >> >> The other way is to use the before_flush event: >> >> http://www.sqlalchemy.org/docs/orm/events.html?highlight=before_flush#sqlalchemy.orm.events.SessionEvents.before_flush >> > > Thanks a lot for the answer. As expected adding my logic in the __init__ was > the way to go. > I have a question though: > Let's say users can edit the detail instances of this master and in case I > detect that certain attribute is modified, I want invalidate the detail and > create > a new one. e.g.: > > if get_history(inst_detail, "attr").has_changes(): > inst_detail.active=False > new_detail = Detail(attr=new_attr, score=100) > master.append(new_detail) > > My question is how I can skip the "attr" modification made in the > old_instance? > I want to keep the active=False but I want to ignore the "attr" change. I > tried with several methods in Session (e.g. expunge) but the update occurs > nevertheless.
I think you'd want to expire inst_detail.active, like with Session.expire(), or you could also try attributes.set_committed_state(inst_detail, 'active', False), should erase the history. -- 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.
