Improve associations

app/models/order.rb

@@ -8,6 +8,7 @@ class Order < ActiveRecord::Base
   has_many :articles, :through => :order_articles
   has_many :group_orders, :dependent => :destroy
   has_many :ordergroups, :through => :group_orders
+  has_many :users_ordered, :through => :ordergroups, :source => :users
   has_one :invoice
   has_many :comments, -> { order('created_at') }, :class_name => "OrderComment"
   has_many :stock_changes

plugins/messages/app/models/message.rb

@@ -42,9 +42,7 @@ class Message < ActiveRecord::Base
 
   def order_id=(order_id)
     @order_id = order_id
-    for ordergroup in Order.find(order_id).ordergroups
-      add_recipients ordergroup.users
-    end
+    add_recipients Order.find(order_id).users_ordered unless order_id.blank?
   end
 
   def recipient_tokens=(ids)