Left outer join

cuuser.rb

class Cuuser < ActiveRecord::Base
	has_and_belongs_to_many :groups
	has_many :messages
	has_many :comments
	has_many :likes

	scope :activeusersleft, -> { joins("LEFT OUTER JOIN comments ON comments.cuuser_id = cuusers.id LEFT OUTER JOIN likes ON likes.cuuser_id = cuusers.id LEFT OUTER JOIN messages on messages.cuuser_id = cuusers.id").
			  select('cuusers.id, count(messages.id) as message_count, count(likes.id) as likes_count, count(comments.id) as comments_count').
			  group('cuusers.id').
			  order('count(comments.id) + count(likes.id) + count(messages.id) desc')}


end

outputconsole

⇒  rails console
Loading development environment (Rails 4.0.3)
2.0.0p353 :001 > Cuuser.activeusersleft

  Cuuser Load (1.5ms)  SELECT cuusers.id, count(messages.id) as message_count, count(likes.id) as likes_count, count(comments.id) as comments_count FROM 
"cuusers" LEFT OUTER JOIN comments ON comments.cuuser_id = cuusers.id LEFT OUTER JOIN likes ON likes.cuuser_id = cuusers.id LEFT OUTER JOIN 
messages on messages.cuuser_id = cuusers.id GROUP BY cuusers.id ORDER BY count(comments.id) + count(likes.id) + count(messages.id) desc

 => #<ActiveRecord::Relation [#<Cuuser id: 1>]>