model add scope

app/models/product.rb

@@ -122,7 +122,7 @@ class Product < ActiveRecord::Base
             rate = (( self.price.to_f - self.buy_price.to_f )/self.buy_price.to_f)*100
         end 
             #return ((rate*100).round.to_f/100).to_s + "%"
-        return admin_user.email
+        return @admin_user.email
     end
 
     rails_admin do