[eluser]OverZealous[/eluser]
[quote author="lsemel" date="1257744054"]The only way I can think to do this is to override save() or create a prepping validation rule, on both sides of the many to many relationship, which seems like a hack.[/quote]
I don't think either of those techniques is a hack. Both would be supported techniques.
There are currently no methods in DMZ anywhere that can notify object A of a save on object B or vice-versa (besides save()). It sounds like a good feature to add in, though. (Like, calling on_related_save just before a relationship save, for example.)
Also: the next version of DMZ (which is ready, but I haven't had time to package), has a new method called include_related_count() which does just that - includes the real-time count of directly-related objects with any query. This might be helpful, although it just uses subqueries, so performance may or may not be an issue in your app still.
