From 5ecb02f6dd60a742d93d306b70be09d6ffb29081 Mon Sep 17 00:00:00 2001
From: Jon Leighton <j@jonathanleighton.com>
Date: Fri, 17 Aug 2012 18:20:12 +0100
Subject: [PATCH] don't call method unless we need to

---
 activerecord/lib/active_record/attribute_assignment.rb | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/activerecord/lib/active_record/attribute_assignment.rb b/activerecord/lib/active_record/attribute_assignment.rb
index 6f6fc13d1608..a54c1034765f 100644
--- a/activerecord/lib/active_record/attribute_assignment.rb
+++ b/activerecord/lib/active_record/attribute_assignment.rb
@@ -106,7 +106,7 @@ def assign_attributes(new_attributes, options = {})
 
       # assign any deferred nested attributes after the base attributes have been set
       nested_parameter_attributes.each { |k,v| _assign_attribute(k, v) }
-      assign_multiparameter_attributes(multi_parameter_attributes)
+      assign_multiparameter_attributes(multi_parameter_attributes) unless multi_parameter_attributes.empty?
     ensure
       @mass_assignment_options = previous_options
     end