Question

Let’s say that

Post has_many :comments

and that

Comment has_many :ratings

How can I grab the last 5 comment ratings for each Post? I’ve been thinking of just looping through comment for each post but that wouldn’t solve the Last 5 part.

EDIT: In response to J. since I can’t seem to format code inside the comments field

Would you be able to nest the :through relationship? say…

class Category < ActiveRecord::Base
  has_many :posts
  has_many :comments, :through => posts
  has_many :ratings, :through => comments
end

class Post < ActiveRecord::Base
  belongs_to :category
  has_many :comments
  has_many :ratings, :through => comments
end

class Comment < ActiveRecord::Base
  belongs_to :post
  has_many :ratings
end

class Rating < ActiveRecord::Base
  belongs_to :comment
end

Answer 1

At the end I was able to get what I was looking for with this under Rails 3

class Category < ActiveRecord::Base
  has_many :posts
  has_many :comments, :through => :posts

  def ratings
    Rating.category_ratings(self)
  end
end

class Rating < ActiveRecord::Base
  belongs_to :comment

  scope :category_ratings, lambda { |c|
    joins(:comment, 'INNER JOIN `posts` ON `posts`.`id` = `comments`.`post_id`').
    where(:posts => {:category_id => c.id}).
    select('DISTINCT `comments`.*')
  }
end