gistfile1.rb

class CommentsController < ApplicationController

  before_action :set_commentable
  before_action :set_comment, only: [:show, :update, :destroy]
  before_filter :authenticate_user!

  def index
    obj = {}
    
    params[:page] = (params[:page].to_i.is_a? Integer) ? (params[:page].to_i > 0 ? params[:page].to_i : 1) : 1
    @comments = @commentable.comments.page(params[:page])
    obj['comments'] = @comments

    if @commentable.comments.page(params[:page].to_i + 1).count > 0
      obj['next'] = params[:page].to_i + 1
    end

    render json: obj
  end
end