Replace ordergroup.account_updated with non database attr.

app/models/ordergroup.rb

@@ -4,7 +4,6 @@
 # 
 # Ordergroup have the following attributes, in addition to Group
 # * account_balance (decimal)
-# * account_updated (datetime)
 class Ordergroup < Group
 
   APPLE_MONTH_AGO = 6                 # How many month back we will count tasks and orders sum
@@ -49,7 +48,6 @@ class Ordergroup < Group
       t = FinancialTransaction.new(:ordergroup => self, :amount => amount, :note => note, :user => user)
       t.save!
       self.account_balance = financial_transactions.sum('amount')
-      self.account_updated = t.created_on
       save!
       # Notify only when order group had a positive balance before the last transaction:
       if t.amount < 0 && self.account_balance < 0 && self.account_balance - t.amount >= 0
@@ -96,6 +94,10 @@ class Ordergroup < Group
     stats.sum {|s| s[:jobs_size].to_f } / stats.sum {|s| s[:orders_sum].to_f }
   end
 
+  def account_updated
+    financial_transactions.last.try(:created_on) || created_on
+  end
+  
   private
 
   # Make sure, that a user can only be in one ordergroup

db/migrate/20121230142516_remove_account_updated_from_ordergroups.rb

@@ -0,0 +1,9 @@
+class RemoveAccountUpdatedFromOrdergroups < ActiveRecord::Migration
+  def up
+    remove_column :groups, :account_updated
+  end
+
+  def down
+    add_column :groups, :account_updated, :datetime
+  end
+end

db/schema.rb

@@ -11,7 +11,7 @@
 #
 # It's strongly recommended to check this file into your version control system.
 
-ActiveRecord::Schema.define(:version => 20121216180646) do
+ActiveRecord::Schema.define(:version => 20121230142516) do
 
   create_table "article_categories", :force => true do |t|
     t.string "name",        :default => "", :null => false
@@ -137,7 +137,6 @@ ActiveRecord::Schema.define(:version => 20121216180646) do
     t.string   "name",                                                   :default => "",    :null => false
     t.string   "description"
     t.decimal  "account_balance",          :precision => 8, :scale => 2, :default => 0.0,   :null => false
-    t.datetime "account_updated"
     t.datetime "created_on",                                                                :null => false
     t.boolean  "role_admin",                                             :default => false, :null => false
     t.boolean  "role_suppliers",                                         :default => false, :null => false