Question

I have a the following models:

class Release < ActiveRecord::Base
    has_many :products, :dependent => :destroy
    has_and_belongs_to_many :tracks
end

class Product < ActiveRecord::Base
    belongs_to :release
    has_and_belongs_to_many :tracks
end

class Track < ActiveRecord::Base
    has_and_belongs_to_many :releases
    has_and_belongs_to_many :products
end

At the moment when I create a Release I can assign tracks to it. When I create a product (under a release) I want it to inherit the tracks assigned to it but be able to amend the order, add and remove tracks.

The reasoning behind this approach is that in most circumstances the tracks will be the same across multiple products so it saves work having to re-list/upload tracks. I could simply pull in tracks from the release, but I must have the facility to alter this, for example there could be an iTunes exclusive with bonus track.

I’m guessing I need to add some lines to the new & create actions of the Product controller to facilitate this? Can anyone offer some guidance?

In the scenario that an extra track not added at release level is later added at product level, how would I make sure it’s included at release level as well?

Would a Jquery drag and drop Release to Product approach be best?

Answer 1

So you could do something as follows:

class Product < ActiveRecord::Base
  belongs_to :release
  has_many :release_tracks, through: :release, source: :tracks      

  has_and_belongs_to_many :tracks

  before_save do
    self.track_ids = self.release_track_ids
  end
end

This way you should always have a list of the original tracks that came with the release, and you have a list of the tracks that are associated with the proudct. Now you can add and remove tracks from the product and always have an idea of which came with the original release.

Hope this helps.