Ruby active record JOIN

gistfile1.txt

class Category < ActiveRecord::Base
  has_many :posts
end

class Post < ActiveRecord::Base
  belongs_to :category
  has_many :comments
  has_many :tags
end

class Comments < ActiveRecord::Base
  belongs_to :post
  has_one :guest
end

class Guest < ActiveRecord::Base
  belongs_to :comment
end


----

Category.all :joins => :posts
#SELECT categories.* FROM categories
  INNER JOIN posts ON posts.category_id = categories.id
  
Post.all :joins => [:category, :comments]
#SELECT posts.* FROM posts 
  INNER JOIN categories ON posts.category_id = categories.id
  INNER JOIN comments ON comments.post_id = posts.id
  
Post.all :joins => {:comments => :guest}
Category.all :joins => {:posts => [{:comments => :guest}, :tags]}

time_range = (Time.now.midnight - 1.day)..Time.now.midnight
Client.all :joins => :orders, :conditions => {'orders.created_at' => time_range}
Client.all :joins => :orders, :conditions => {:orders => {:created_at => time_range}}