rurabe

    last_three_posts = Post.limit(3).order(created_at: :desc)
    @posts = Comment.where(post_id: last_three_posts)

    class Comment
      scope :with_vote_count, ->{ joins(:votes).select('comments.*').select('count(votes.*) as vote_count') }
    end

    class Post
      has_many :comments
      has_many :comments_with_vote_counts, ->{ with_vote_counts }, class_name: 'Comment'
    end

    # in controller
    @posts = Post.includes(:comments_with_vote_counts).limit(3).order(:created_at: :desc)

    # in view/serializer, posts and comments are both AR instances
    @posts.each do |post|
      post.comments.each do |comment|
        comment.vote_count # => Integer
      end
    end