Question

I`m new to RoR. Please help me:
I have two models:

class User < ActiveRecord::Base
  belongs_to :game
end

and

class Game < ActiveRecord::Base
  has_many :users, :foreign_key => "game_id"
end

Game objects have many users. I need to find all Game objects, where users.count == 1. Please help.

Answer 1

A bit long but this worked for me:

 Game.joins(:users).where("(select count(users.game_id) from users users2 where users2.game_id = games.id) = 1")

You can use includes() or joins() depending on what you want to do.