Rails 3: include a field from has_many through association

My model association is as follows:

#book model class Book < ActiveRecord::Base has_many :recommendations, :dependent => :destroy has_many :similars, :through => :recommendations, :conditions => ['recommendation_type IS NULL'], :order => 'recommendations.created_at DESC'

#recommendation model class Recommendation < ActiveRecord::Base belongs_to :book

#Books_controller - injecting the recommendation_id @book_similars = Book.similars @book_similars.each do |similar|   @rec_id = Recommendation.where(:book_id=>similar.id, :recommendation_type=>'S').select('id').first.id   similar << {:rec_id => @rec_id}   # ^-- Above line gives NoMethodError (undefined method `<<' for #<Book:0x10de1f40>): end

So as noted above, A book has many similars through recommendations. My requirement is that while retrieving similars, I would also like to include the id of the corresponding record in the join table recommendations. My questions are:

How can I include the field *recommendation_id* alongwith similars?

If it cannot be included directly, then what is the correct way to determine this field separately (as shown above) and then inject it into the similars instance variable so that I can use it directly in my views?

You have not told us whether recomendation has_many similars or belongs_to similar. The answer depends on that I think. Your question may only make sense one way round but I would like confirmation.

Colin

you have to do an extra loop to get "recommendation_id" I think your @rec_id should be an array

I have had problems with has_many through in the past personally I try to avoid it.