On 7/4/07, psnively <[EMAIL PROTECTED]> wrote: > > > Apart for an existing DB where a specific table handles this one-to-one > > relation, what is the benefit of this method over the > > belongs_to / has_one syntax ? You also get a bidirectional association, > > don't you ? > > You do, but it's strictly 1-1 or 1-N (in whatever direction). In other > words, when you change the reference on either end, you... change the > reference. With has_and_belongs_to(uselist=False), you get > bidirectional (a named attribute on both models), 1-1 (each reference > is singular), but each entity can have a distinct reference to some > other distinct entity--that is, under the hood, an association table > is still created, and the foreign key references on the entities > actually refer to that association table, which in turn refers to the > other entity. You seem to be confused by what an has_and_belongs_to_many does. There are no foreign key from the entities to the association table. Only from the association table to both entities!
> This prevents weird semantics (from the object-oriented > perspective), where an entity can only be associated with a single > other entity, and "vanishes" from the entity it was previously > associated with when the reference on the parent entity is changed. This also happens when using has_and_belongs_to_one (or whatever you call it). So, I really don't see the point in your change, except to support a database doing it this way already (as noted by Remi), and this seem rare enough to stay out of the main distribution. -- Gaëtan de Menten http://openhex.org --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "SQLElixir" 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/sqlelixir?hl=en -~----------~----~----~----~------~----~------~--~---
