Rails Table Relations questions

Hello,

I'm breaking my head atm about table relations / associations in
Rails.

The idea is this: Collections has many mods, mods have many folders,
folders have many items.
A collection can have many different versions, the mods associated
with a collection, should 'have the same version'.
Changelogs are linked to Version, but should differ per Mod.

If I work with ActiveScaffold, things become quite a mess, and I can
for instance create a Changelog entry, for a mod that is not part of
the chosen Collection, and so on.

This is basically what I have atm:
class Collection < ActiveRecord::Base
   has_many :mods
   has_many :versions
end

class Version < ActiveRecord::Base
  belongs_to :collection
  has_many :changelogs
end

class Mod < ActiveRecord::Base
   belongs_to :collection
   has_many :folders
   has_many :changelogs
end

class Changelog < ActiveRecord::Base
  belongs_to :version
  belongs_to :mod
end

class Folder < ActiveRecord::Base
  belongs to :mod
  has_many :folders
end

class Item < ActiveRecord::Base
  belongs to :folder
end

Anybody any ideas? Cheers

If I’ve understood your problem correctly, I would map the core relationships as you have described them and then use validation to ensure the business rules such as a mod of a collection must be of the same version as the collection.

You can use the validation method or perhaps before_save callbacks depending on which suits what you’re doing better.