unique filenames per album

app/models/photo.rb

@@ -2,6 +2,7 @@ class Photo < ActiveRecord::Base
   attr_accessor :file
   
   validates_presence_of :author_id, :album_id
+  validates_uniqueness_of :filename, :scope => :album_id
   
   belongs_to :album
   belongs_to :author
@@ -108,4 +109,4 @@ class Photo < ActiveRecord::Base
     end
     Dir.delete(base_directory)
   end
-end
+end