> id use an association table with its own entity to make things > easy. hm, u mean... A.link references that table by single id, and the table contains the tuple (discriminator,id) ? But isn't this another sort of table-inheritance? looks like a join to me... not that i'm big specialist on joins. And how to automate the secondary loadby(discriminator,id)?
> On Feb 21, 2007, at 10:05 AM, svilen wrote: > > g'day. > > > > How one can make such thing as a reference to concrete-inherited > > polymorphic mapper? > > e.g. if there are just two, A and B, B inherits A, both have full > > concrete tables. A has polymorphic mapper. > > > > If both tables have separate primary ids, they will overlap as > > values - table_A.id=1 for some A() and table_B.id=1 for some B() > > are both ok; hence, query(A).getby_id(1) would return 2 objects > > via the polymorphic union. > > in this case, the unique key within the polymunion seems to be > > the id+type_discriminator; where type_discriminator effectively > > means "this id is from that table". > > > > i see 2 possibilities here: > > > > - use 2-field key: a tuple of discriminator(table_name) and > > id-in-that-table. How would one make references to those objects > > then? e.g. what would be the definition of Column( 'mylink_id', > > ...) be ? it becomes a link to multiple tables... Would the > > propertyLoaders support such multi-column key? or make some > > constructed single key instead? > > > > - use one common sequence for filling both primary-keys of both > > tables. But this is limited to DBs which support sequences... > > > > Any help? > > > > ciao > > svil > > --~--~---------~--~----~------------~-------~--~----~ 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 [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~----------~----~----~----~------~----~------~--~---
