Mike, a question related to you saying "composites aren't a necessary feature in the first place". Would it be possible using just Python properties and synonym() to do something similar to the composites example in the doc, namely query(Vertex).filter(Vertex.start == Point(3, 4))? Thanks. Eric
2008/8/21, Michael Bayer <[EMAIL PROTECTED]>: > > > On Aug 21, 2008, at 9:03 AM, [EMAIL PROTECTED] wrote: > >> >> hi >> i plan to implement "embedded structures" in dbcook (as opposed to >> referenced structures living in separate tables), and composite props >> seems to fit nicely. >> >> the idea is to achieve something like: >> >> class Point( embeddableBase): >> x = Int() >> y = Int() >> >> class Vertex( base): >> p1 = Point() >> p2 = Point() >> >> which should create a table/mapping >> with columns ( p1_x, p1_y, p2_x, p2_y ) and a mapper with the p1, p2 >> as composite_props. >> >> the plain columns are still accessible via the mapper, right? e.g. >> query(Vertex).filter( Vertex.p1_x >4 ) >> can composite's props be used in query expressions? e.g. >> query(Vertex).filter( Vertex.p1.x > 4 ) > > Not by default, the composite attribute p1 and p2 would prevent p1_x, > p1_y, etc. from being mapped. you could try explicitly mapping them, > i havent experimented much with that. it becomes a gray area since > which attribute would it favor for the ultimate value to be > persisted? plain descriptors look like a better solution here > (composites are probably an unnecessary feature in the first place). > >> >> >> can composite's props be assigned separately ? e.g. would this work? >> v = Vertex( ...) >> v.p1.x = 3 >> v.p2 = Point( 1,2) >> v.p1_y = 5 > > > yeah that wont work at all. With a descriptor based approach (and a > Point object that knows how to proxy to the parent object), it could. > > > > > --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
