Question

我需要用户获得5篇观看次数最多的文章。为此，我实现了“印象”功能，文章和印象模型之间存在多态关系。使用此功能，我无法获得每篇文章从用户获得的观点。但是现在我需要从db获取5篇最受欢迎的文章。我知道这是一个愚蠢的问题，但我试过，但找不到答案。

schema.rb（我没有粘贴完整文件但只是相关的）

ActiveRecord::Schema.define(:version => 20130419101017) do

  create_table "articles", :force => true do |t|
    t.string   "title"
    t.text     "body"
    t.datetime "created_at", :null => false
    t.datetime "updated_at", :null => false
    t.integer  "user_id"
  end

  create_table "comments", :force => true do |t|
    t.text     "content"
    t.integer  "user_id"
    t.string   "article_id"
    t.datetime "created_at", :null => false
    t.datetime "updated_at", :null => false
  end

  create_table "impressions", :force => true do |t|
    t.string   "impressionable_type"
    t.integer  "impressionable_id"
    t.integer  "user_id"
    t.string   "ip_address"
    t.datetime "created_at",          :null => false
    t.datetime "updated_at",          :null => false
  end

articles_controller.rb

class ArticlesController < ApplicationController
  before_filter :is_user_admin, only: [:new, :create, :edit, :destroy]
  before_filter :log_impression, :only=> [:show]

    def is_user_admin
      redirect_to(action: :index) unless current_user.try(:is_admin?) 
      return false 
    end

   def log_impression
     @article = Article.find(params[:id])
     # this assumes you have a current_user method in your authentication system
      @article.impressions.create(ip_address: request.remote_ip,user_id:current_user.id)
   end

      def index
          @articles = Article.all(:order => "created_at DESC")
      @article_titles = Article.first(10)
      @article_popular = Article. 
      @tags = Tag.all
      end

    def show
       @article = Article.find(params[:id])
       @related_articles = Article.joins(:taggings).
       where('articles.id != ?', @article.id)
       .where(taggings: { tag_id: @article.tag_ids }) 
    end

      def new
      @article = Article.new
      end

    def create
      @article = Article.new(params[:article])
      @article.user_id = current_user.id
      if @article.save
        flash[:success] = "article created!"
        redirect_to article_path(@article)
      else
        render 'new' 
      end 
    end

    def destroy
      @article = Article.find(params[:id])
      @article.destroy
      redirect_to action:  'index'  
    end

    def edit
      @article = Article.find(params[:id])
    end

    def update
      @article = Article.find(params[:id])
      if @article.update_attributes(params[:article])
       flash.notice = "Article '#{@article.title}' Updated!"
       redirect_to article_path(@article)
      else 
        render 'edit'
      end
    end
end

article.rb

class Article < ActiveRecord::Base
   attr_accessible :title, :body
   attr_accessible :tag_list
   has_many :comments
   belongs_to :user
   has_many :taggings
   has_many :tags, through: :taggings
   has_many :impressions, :as=>:impressionable
   validates :title, :body, :tag_list,  :presence => true

  def impression_count
    impressions.size
  end

  def unique_impression_count
    impressions.group(:ip_address).size #UNTESTED: might not be correct syntax
  end


   def tag_list
     self.tags.collect do |tag|
      tag.name
     end.join(", ")
   end

   def tag_list=(tags_string)
     tag_names = tags_string.split(",").collect{|s| s.strip.downcase}.uniq
     new_or_found_tags = tag_names.collect { |name| Tag.find_or_create_by_name(name) }
     self.tags = new_or_found_tags
   end
end

impression.rb

class Impression < ActiveRecord::Base
  attr_accessible :impressionable_id, :impressionable_type, :ip_address, :user_id
  belongs_to :impressionable, :polymorphic=>true 
end

物品/ show.html.erb

Viewed: <%=@article.impression_count %> times

这是我计算用户观看次数的方法。现在我希望用户获得5篇观看次数最多的文章。任何帮助都会令人欣慰。有关详细信息，我使用了（simple hit counter for page views in rails）来获取用户视图。

Answer 1

我认为，为了避免映射ruby对象，最好的方法是使用counter cache：

# add the impression count column to your tables
t.integer :articles, :impressions_count
t.integer :comments, :impressions_count

在你的模特中：

class Article < AR
  has_many :impressions, as: :impressionable
  has_many :comments
end

class Comment < AR
  belongs_to :article
  has_many :impressions, as: :impressionable
end

class Impression < AR
  # the counter cache here is the important option
  belongs_to :impressionable, polymorphic: true, counter_cache: :impressions_count
end

每次创建展示时都会使用此设置，正在更新相应模型中的impressions_count列。因此，您可以简单地对展示次数进行排序，以获得最高的5个展示次数：

Article.order('articles.impressions_count DESC').limit(5)

分别

Comment.order('comments.impressions_count DESC').limit(5)

当然，你也可以做@article.impressions_count ......

Answer 2

您是否尝试过：

impressions = Impression.select("impressionable_id, count(*) as qty").where("impressionable_type = ?", 'Article').group('impressionable_type, impresionable_id').order('qty desc').limit(5)
Article.joins(:impressions).where(impressions: {impresionable_id: impressions.map(&:impressionable_id)})

如何在铁轨上获得5个最受欢迎的文章

2 个答案: