update prices fails if list price is smaller than input price

back-office/app/models/item.rb

@@ -15,6 +15,7 @@ class Item < ActiveRecord::Base
 
 
   validates_presence_of :name, :description, :list_price, :current_input_price, :tags, :unit_id, :code, :sub_category_id, :weight, :supplier_id
+  validate :we_must_earn_money
 
   def self.items_to_order
     items_raw = Item.find_by_sql(%Q{
@@ -124,5 +125,11 @@ class Item < ActiveRecord::Base
     puts nonexistent_codes.join("\n")
   end
 
+  def we_must_earn_money
+    if list_price.to_f <= current_input_price.to_f
+      errors[:list_price] << "#{code} Ulazna cijena veca od izlazne"
+    end
+  end
+
 
 end