Very interesting!
I'll try tomorrow.
Thanks a lot, Dave.
On Fri, Jun 25, 2010 at 1:21 AM, dlypka <dly...@gmail.com> wrote:
> I've done a parent - to - many child GAE / web2py implementation using
> SelfReference fields (or you can use Reference as well) using the
> technique for adding native GAE fields into a web2py table definition.
>
> It gives fantastic retrieval performance because GAE automatically
> adds the link from the child back into the parent's reference list
> at the time you create each child. When you later query for the
> parent, voila GAE retrieves all the child entities along with it in
> one backend call!
>
> Hopefully this technique is relevant to your application.
>
> I also develop some other tricks for inheriting native GAE classes
> into your web2py model, though
> this is less attractive perhaps now that GAE native properties can be
> directly declared in web2py tables.
>
> - Dave Lypka.
>
> On Jun 21, 10:25 am, Carles Gonzalez <carle...@gmail.com> wrote:
>> Hi,
>>
>> I have developed some applications in web2py, and 2 are running
>> currently in gae, but now i have serious problem.
>>
>> My current project is a social application, and when i design
>> (example) the tables to make an user follow the actions other user
>> (twitter like) I find that many-to-many relationships in app-engine
>> are not easily supported.
>>
>> From my understanding using the tools present in web2py right i would
>> need to do a lot of processing in memory, an that would hurt
>> performance greatly.
>>
>> The pattern proposed by app store developers uses lists and "parent"
>> relationship:
>>
>> class Message(db.Model):
>> sender = db.StringProperty()
>> body = db.TextProperty()
>>
>> class MessageIndex(db.Model):
>> receivers = db.StringListProperty()
>>
>> indexes = MessageIndex.all(keys_only = True).filter('receivers = ', user_id)
>> keys = [k.parent() for k in indexes)
>> messages = db.get(keys)
>>
>> For using that pattern in web2py I would need a method for specifying
>> the parent of a model instance. Can I specify that relationship using
>> any method I don't know? If not, would it be hard to implement?
>>
>> Thanks in advance!
