通过计数

Question

加入嵌套协会，团体和秩序我有嵌套的模型结构：

class Forum < ActiveRecord::Base 
    has_many :topics 

class Topic < ActiveRecord::Base 
    has_many :posts 
    belongs_to :forum 

class Post < ActiveRecord::Base 
    belongs_to :topic 
    has_many :post_links 
    has_many :links, ->{ uniq }, through: :post_links, dependent: :destroy 

class PostLink < ActiveRecord::Base 
    belongs_to :post 
    belongs_to :link 

class Link < ActiveRecord::Base 
    has_many :post_links 
    has_many :posts, ->{ uniq }, through: :post_links, dependent: :destroy 

所以我想这是帖子说是主题，在论坛，ID = 1

所有链接

按照论坛中出现的次数降序排列。

所以，如果我有一些职位youtube.com 5次论坛，ID = 1，和10时google.com话，我想有这样的：

id,name,mentions_count 
1,google.com,10 
2,youtube.com,5 

Answer 1

Forum.where(id: 1).joins(topics: [posts: [:links]]).order("count_all DESC").group("links.host").count 
=> {"youtube.com"=>5, "google.com"=>2} 

我假设你有在你的链接表中的主机列