gistfile1.txt

...
  def feeds_counts
    @result = []
    current_user.feeds.each do |feed|
      @result << {
        id: feed.id,
        title: feed.title,
        count: feed.post_count_since_last_read
      }
    end

    respond_to do |format|
      format.json { render json: @result }
    end
  end
...

my code

...

def feeds_counts
    respond_to do |format|
      format.json { render json: (@result = current_user.feeds.map(&:to_feed_count_json)) }
    end
  end

...

class Feed < ActiveRecord::Base

  ...

  def to_feed_count_json
    { 
      id: id, title: title, 
      count: post_count_since_last_read
    }
  end

  ...
end