On Mar 11, 8:43 pm, "chasfs" <[EMAIL PROTECTED]> wrote: > ORM has been contentious for many years - for more background on the > problems of > ORM, check out Ted Neward's blog entry > -http://blogs.tedneward.com/2006/06/26/The+Vietnam+Of+Computer+Science... > > Peace, > -chasfs That for the link. Not a bad article (once you wade through the Vietnam stuff). But the author has only one paragraph on this topic: "Inheritance mapping isn't the end of it; associations between objects, the typical 1:n or m:n cardinality associations so commonly used in both SQL and/or UML, are handled entirely differently: in object systems, association is unidirectional, from the associator to the associatee (meaning the associated object(s) have no idea they are in fact associated unless an explicit bidirectional association is established), whereas in relational systems the association is actually reversed, from the associatee to the associator (via foreign key columns). This turns out to be surprisingly important, as it means that for m:n associations, a third table must be used to store the actual relationship between associator and associatee, and even for the simpler 1:n relationships the associator has no inherent knowledge of the relations to which it associates--discovering that data requires a JOIN against any or all associated tables at some point. (When to actually retrieve that data is a subject of some debate--see the Loading Paradox, below)." We already know that associations are reversed between OO and relational worlds, and it's not really that hard to accommodate, especially in Django where the relational schema is completely based off the OO schema. All that really needs to be done is to either add an attribute to model.ForeignKey to specify the direction of the association, or to create a new class to represent this type of association. The DB schema doesn't need to change at all, but some queries like get_related() might. I've heard the argument that Django is only making certain common use cases simple, and that for any real project "scaffolding is meant to be torn down". I can only assume that this particular use case (basically just composition), being pretty elemental to OO design, is very common. I also hope that newforms will mean that more of the built-in forms functionality is going to usable in production. As opposed to having everyone implement their own version, it'd benefit everyone to have it standardized. Simon, I hope to implement this also, once things calm down a little. Feel free to contact me. -Justin --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Django users" group. To post to this group, send email to django-users@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/django-users?hl=en -~----------~----~----~----~------~----~------~--~---
