Rails habtm：选择至少有一个关联的所有内容

Question

I have 2 models:

class Section < ActiveRecord::Base
  has_and_belongs_to_many :posts
end

and

class Post < ActiveRecord::Base
  has_and_belongs_to_many :sections
end

I need to select all sections that has at least one associated post and order this sections by count of assotiated posts. Can anyone help me?

Answer 1

I had no opportunity to test this code, but it looks about right.

Section.select("sections.*, count(posts.id) AS post_count").
  joins(:posts).
  group("sections.id").
  order("post_count DESC")