Dear all,
I've been trying to answer my own question and use the
attribute_mapped_collection component like this :
mapper(Tournament, tournaments_table, properties={
"subscriptions": relationship(Subscription,
order_by=[desc(Subscription.status), Subscription.user_id],
collection_class=attribute_mapped_collection('user'))
})
Now, the following code works :
def subscribe(self, user, status):
current_subscription = self.subscriptions.get(user)
if current_subscription :
current_subscription.status = status
else :
self.subscriptions[user] = Subscription(user, status)
1. Is it good ? My tables are small, maybe I don't need such logic in the
mapping ?
2. The key is a "user" object (not an id), so more DB SQL will be issued,
right ?
3. Now, with the subscriptions mapped as a dictionary, the order_by clause
does not seem to work, which makes sense (subscriptions.values() is not
ordered). How could I force the order_by nevertheless ?
Thanks a lot !
Franck
On Mon, Jan 10, 2011 at 7:05 PM, Franck <[email protected]> wrote:
> Dear all,
>
> I'm developing a website aimed at handling tournaments' results and
> subscriptions.
> One subscription is bound to one user and one tournament.
>
> subscriptions_table = Table('SUBSCRIPTIONS', metadata,
> ...
> Column('tournament_id', Integer,
> ForeignKey('TOURNAMENTS.id')),
> Column('user_id', Integer, ForeignKey('USERS.id')),
>
> Here are the mappers (I'm not sure I actually need the backref) :
>
> mapper(Tournament, tournaments_table, properties={
> "subscriptions": relationship(Subscription, backref="tournament")
> })
>
> mapper(Subscription, subscriptions_table, properties={
> "user": relationship(User)
> })
>
> When the user clicks "Subscribe" on the page, the model is checking if the
> user already subscribed to the current tournament or not. If yes,
> SUBSCRIPTIONS.UPDATE should be issued, otherwise SUBSCRIPTIONS.INSERT
>
> As you can see, it's a very classical scenario.
>
> Here's how I implemented the "subscribe" method... but I don't like it at
> all :
>
> class Tournament(Base):
>
> def subscribe(self, user, status):
>
> # Works, but dirty ! Why should I manually query RESULTS since I
> have access to self.subscriptions ?
> # Should I manually look the user in [subscription .user for
> subscription in self.subscriptions] ?
> current_subscription = orm.query(Result).filter(Result.tournament
> == self).filter(Result.user == user).first()
>
> if current_subscription :
> current_subscription.status = status
> else :
> self.subscriptions.append(Subscription(user, status))
>
> # Commit / rollback logic
>
>
> What do you think ? Since self.subscriptions is already bound, how should I
> properly filter it by user ?
>
> Thanks very much for your help !
> Franck
>
>
>
>
>
>
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