search for: grouping_ids

OK I give up, how do I do this... I have a DB that stores dynamic variables with I group into group_id''s. For instance here are a couple examples of db rows: title="name", description = "john", grouping_id = "1" title="location", description = "USA", grouping_id = "1" title="comment", description = "hello",

...in 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