View difference between Paste ID: r7kzbr3t and Gkwm7Bc2

 #models/item.rb
 class Item < ActiveRecord::Base
   attr_accessible :item_votes_count, :name, :price, :taobaoke_url, :original_url, :topic_id, :image, :image_cache, :remote_image_url
   belongs_to :topic, counter_cache: true
   belongs_to :user
   has_many :item_votes, dependent: :destroy
 
   validates :name, :taobaoke_url, :topic_id, :original_url, presence: true
   validates :price, presence: true, numericality: true
 
   mount_uploader :image, ItemImageUploader
   store_in_background :image
 
   scope :order_by_votes, order('item_votes_count desc')
   scope :order_by_create_time, order('created_at desc')
 
   def vote(by)
     return false unless by
     return false if voted_by?(by)
     item_votes.create!(vote: 1, user_id: by.id)
   end
 
   def voted_by?(user)
     return false unless user
     !item_votes.by_user(user).size.zero?
   end
 
   def votes(options = {})
     reload = options[:reload]
     reload ? item_votes.count : item_votes.size
   end
 
 end
 
 #uploaders/item_image_uploader.rb
 class ItemImageUploader < CarrierWave::Uploader::Base
   include CarrierWave::MiniMagick
   include CarrierWave::Backgrounder::Delay
 
   def store_dir
     "uploads/#{model.class.to_s.underscore}/#{mounted_as}/#{model.id}"
   end
   # Create different versions of your uploaded files:
   version :s250x300 do
     process resize_to_fill: [250, 300]
   end
 
   version :s100 do
     process resize_to_fill: [100, 100]
   end
 end
 
 
 #models/topic.rb
 class Topic < ActiveRecord::Base
   attr_accessible :desc, :items_count, :name, :button_name, :user_id, :image, :image_cache
   has_many :items, dependent: :destroy
   belongs_to :user, counter_cache: true
 
   validates :name, :button_name, :user_id, presence: true
 
   mount_uploader :image, TopicImageUploader
   store_in_background :image
 
 end
 
 
 #controllers/topics_controller.rb
 class TopicsController < ApplicationController
   load_and_authorize_resource
   before_filter :require_login, except: [:index, :show]
 
   def index
     count = params[:count] ? params[:count].to_i : 12
     page = params[:page] ? params[:page].to_i : 1
     @topics = Topic.page(page).per(count)
 
     respond_to do |format|
         format.html # index.html.erb
       format.json { render json: @topics }
     end
   end
 
 
 #views/topics/index.html.erb
 <header class="header">
 <a href="/"><span class="logo"></span></a>
 <%= link_to('New Topic', new_topic_path) if can? :create, Topic %>
 </header>
 
 <section class="wrapper">
   <ul class="topic-list">
     <% @topics.each do |topic| %>
       <li>
         <a href="<%= topic_path(topic) %>">
           <h3 class="topic-list-title"><%= topic.name %></h3>
           <div class="topic-list-imgs">
             <% items = topic.items.order_by_votes.first(9) %>
             <% if !items.empty? %>
             <ul>
               <% items.each do |item| %>
                 <li>
                   <img src="<%= item.image_url(:s100) %>" alt="<%= topic.name %>">
                 </li>
               <% end %>
             </ul>
             <% else %>
               <img src="<%= topic.image_url(:s300) %>" alt="<%= topic.name %>">
             <% end %>
           </div>
         </a>
       </li>
     <% end -%>
   </ul>
   <%= paginate @topics %>
 </section>