This isn't something that's going to be easy in any ORM, but here's an idea.
What about caching a list of the members of a Grouping in an attribute? You'd need to include the type obviously, so it would look something like this: 'bar:1,bar:5,foo:2,frob:14' You'd need to update this field when adding an element, and then validates_uniqueness_of and/or unique key it in the DB. Also note that you'll want to sort it, otherwise you'll run into problems. Dealing with users concurrently adding things to Groupings is a whole 'nother bucket of hurt, which will be trickier to deal with. --Matt Jones On Oct 23, 3:13 pm, raji <[email protected]> wrote: > Ok, that's not the best subject line, but I couldn't think of a > concise way to describe what I'm trying to do. > > I've got two models. Grouping simply contains an id and a few other > attributes (e.g. rating). A grouping can contain many elements which > are stored the Element model. > > A set of elements is tied together by a grouping_id. An element can > be one of several types of objects. I'm doing this with polymorphic > associations. > > I need a way to ensure that a grouping is unique. That is, there > should not be two grouping_ids containing the exact same elements. > > The closest analogy I can think of is a composite primary key. > Except, this is across multiple rows (instead of columns) and uses > polymorphic association types and ids. > > Can this be easily done with Rails and ActiveRecord? > > Thanks, > Raj --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" 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/rubyonrails-talk?hl=en -~----------~----~----~----~------~----~------~--~---
