Hi Eric, Thank you, I actually used this documentation (even though they are only many-to-many) and some other blog post to come up with this solution. Using 0.7 I don't have event on Mixin so I had to find an alternative to event attachment. BTW I'm pretty surprised by the speed of the event solution provided by SQLAlchemy, as I always heard that event listener on DB object were evil, but it turned out to almost add no overhead (test operated 2k object creation).
On Sat, Dec 1, 2012 at 10:35 PM, Eric Ongerth <[email protected]> wrote: > Hi Brice, > > Yours is another good case of the 'Generic Associations' or 'Polymorphic > Association' pattern which comes up quite often. Here's a link to some > docs that will get you going on a good solution that keeps the database > normalized. > > > http://docs.sqlalchemy.org/en/rel_0_8/orm/examples.html#generic-associations > > If that doesn't get you off and running, especially the example in > discriminator_on_association.py, continue this thread or pop into the IRC > channel. > > - ejo > > > On Wednesday, November 28, 2012 1:20:52 PM UTC-8, deBrice wrote: > >> So here is my solution, >> >> https://gist.github.com/**4164619 <https://gist.github.com/4164619> >> >> Hope it helps others to get an insight on generic relation in SQLAlchemy. >> >> >> On Tue, Nov 27, 2012 at 7:41 AM, Brice Leroy <[email protected]> wrote: >> >>> Thank you for the advice Robert. As I'm using flask I'm not sure how >>> adaptable the ZCA would be. I'll try to understand the logic behind it and >>> see if I can replicate it within my models. >>> >>> >>> On Tue, Nov 27, 2012 at 7:12 AM, Robert Forkel >>> <[email protected]>wrote: >>> >>>> hi, >>>> i used to do something like this, i.e. adding information about urls, >>>> views, etc. to sqlalchemy models, but found this to be inflexibel. Now >>>> I keep URL-related information in the web app's routing component, and >>>> to solve problems like the one you pose, I use zca adapters [1] (which >>>> is easier when using pyramid, because you already have a component >>>> registry available). So with this technology you'd register the same >>>> FeedItem class as adapter for the various sqlalchemy models, which >>>> means that at adaption time, the object to adapt will be passed to >>>> you. >>>> regards >>>> robert >>>> >>>> [1] >>>> http://www.muthukadan.net/**docs/zca.html<http://www.muthukadan.net/docs/zca.html> >>>> >>>> >>>> On Tue, Nov 27, 2012 at 3:58 PM, Brice Leroy <[email protected]> >>>> wrote: >>>> > Hello everybody, >>>> > >>>> > It's about brainstorming on an elegant solution. I previously posted >>>> this >>>> > question on the Flask mailing list, and I got advised to post it on >>>> > SQLAlchemy list... which make more sense I admit. So here is my issue: >>>> > >>>> > I have N different classes: >>>> > >>>> > class Comment(Models): >>>> > author_id = Integer >>>> > comment = String >>>> > creation_date = Date >>>> > >>>> > class Picture(Models): >>>> > author_id = Integer >>>> > image = File >>>> > creation_date = Date >>>> > ... >>>> > >>>> > now let say, I have a "follow" feature, allowing a user X to get >>>> updates >>>> > when Y (the user followed by X) does something (creepy...). >>>> > >>>> > So far I came up with something like that: >>>> > >>>> > class FeedItem(Model) >>>> > table = String >>>> > key = Integer >>>> > creation_date = Date >>>> > >>>> > def url(self): >>>> > #get object by querying self.table with self.key >>>> > object = self.get_an_object(table=self.**table, key=self.key) >>>> > return object.view_url >>>> > >>>> > and then add this property to Comment and Picture classes: >>>> > >>>> > @property >>>> > def view_url(self): >>>> > return url_for('view_function_name', self.id) >>>> > >>>> > - What would be your way of dealing with this kind of "open/generic" >>>> > relationship items? >>>> > >>>> > - How would you manage automatic deletion of a FeedItem when the >>>> object it >>>> > points to get destroyed? (I'm thinking attaching function on delete >>>> event to >>>> > classes) >>>> > >>>> > - Would you create as many FeedItem per follower, or use a Table to >>>> link >>>> > them to followers, therefore deleting a FeedItem would automatically >>>> delete >>>> > the relation record from the Table.? >>>> > >>>> > Thank you, >>>> > >>>> > -- >>>> > Brice >>>> > >>>> > -- >>>> > You received this message because you are subscribed to the Google >>>> Groups >>>> > "sqlalchemy" group. >>>> > To post to this group, send email to [email protected]. >>>> >>>> > To unsubscribe from this group, send email to >>>> > sqlalchemy+...@**googlegroups.com. >>>> >>>> > For more options, visit this group at >>>> > http://groups.google.com/**group/sqlalchemy?hl=en<http://groups.google.com/group/sqlalchemy?hl=en> >>>> . >>>> >>>> -- >>>> You received this message because you are subscribed to the Google >>>> Groups "sqlalchemy" group. >>>> To post to this group, send email to [email protected]. >>>> To unsubscribe from this group, send email to sqlalchemy+...@** >>>> googlegroups.com. >>>> >>>> For more options, visit this group at http://groups.google.com/** >>>> group/sqlalchemy?hl=en<http://groups.google.com/group/sqlalchemy?hl=en> >>>> . >>>> >>>> >>> >>> >>> -- >>> -- >>> Brice >>> >>> >> >> >> -- >> Brice >> >> -- > You received this message because you are subscribed to the Google Groups > "sqlalchemy" group. > To view this discussion on the web visit > https://groups.google.com/d/msg/sqlalchemy/-/fIkNEtwTaH8J. > > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]. > For more options, visit this group at > http://groups.google.com/group/sqlalchemy?hl=en. > -- Brice -- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
