The object doesn't move from one relation to another : this is the
same relation 'entries' but on a different parent. This is common to
any parent.child pattern, not a business specific case.
The current behavior is not consistent because as soon as we commit()
+ refresh(), the object is not on accountA anymore (entry.account_id
has changed). This end result should be reflected in memory just after
the change too (i.e. before commit).
On Apr 6, 1:10 pm, Mike Conley <mconl...@gmail.com> wrote:
> So, we would like SA to have some kind of operation like "reparent_item()"
> that would move an object from one relation to another.
> It seems to me that this is is better handled as a piece of application
> business logic. In this case, provide a "move_entry()" function that
> properly encapsulates inserting and removing the entry in a single
> operation. I can imagine that there would be many variations on business
> rules for moving an item that would be difficult to encapsulate in a common
> operation within SA.
>
> --
> Mike Conley
>
> On Mon, Apr 6, 2009 at 2:10 AM, jean-philippe dutreve
> <jdutr...@gmail.com>wrote:
>
>
>
> > Currently, I use accountA.remove(entry) and I have rewritten insort to
> > bypass the bug you say.
>
> > So, AFAIK, whereas an entry has only one account (via
> > entry.account_id), SA can't remove the first relation.
> > It's dangerous, because if developer forget to remove the first
> > relation, the entry is contained in 2 accounts temporaly.
> > It can lead to false computation (when summing balance for instance).
>
> > On 5 avr, 22:03, jason kirtland <j...@discorporate.us> wrote:
> > > jean-philippe dutreve wrote:
> > > > Hi all,
>
> > > > I wonder if SA can handle this use case:
>
> > > > An Account can contain Entries ordered by 'position' attribute.
>
> > > > mapper(Account, table_accounts, properties = dict(
> > > > entries = relation(Entry, lazy=True, collection_class=ordering_list
> > > > ('position'),
> > > > order_by=[table_entries.c.position],
> > > > passive_deletes='all', cascade='save-update',
> > > > backref=backref('account', lazy=False),
> > > > ),
> > > > ))
>
> > > > I'd like to move an entry from accountA to accountB and let SA remove
> > > > the link between the entry and accountA:
>
> > > > entry = accountA.entries[0]
> > > > insort_right(accountB.entries, entry)
> > > > assert not entry in accountA.entries # false, entry is still in
> > > > accountA !!!!
>
> > > > It is possible?
>
> > > Try removing the entry from accountA:
>
> > > entry = accountA.pop(0)
> > > ...
>
> > > Also beware that bisect insort has a bug that prevents it from working
> > > properly with list subclasses like ordering_list (or any SA list-based
> > > collection). I think it's fixed in Python 3.0, not sure if the fix was
> > > backported to 2.x.
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