From 675094b2757cf90399dadca4489b1036810ae570 Mon Sep 17 00:00:00 2001
From: Santiago Pastorino <santiago@wyeworks.com>
Date: Thu, 5 Jan 2012 20:15:52 -0200
Subject: More 1.9 way

---
 activemodel/lib/active_model/conversion.rb | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/activemodel/lib/active_model/conversion.rb b/activemodel/lib/active_model/conversion.rb
index 80a3ba51c3..c7c805f1a2 100644
--- a/activemodel/lib/active_model/conversion.rb
+++ b/activemodel/lib/active_model/conversion.rb
@@ -39,11 +39,9 @@ module ActiveModel
 
     # Returns an Enumerable of all key attributes if any is set, regardless
     # if the object is persisted or not.
-    #
-    # Note the default implementation uses persisted? just because all objects
-    # in Ruby 1.8.x responds to <tt>:id</tt>.
     def to_key
-      persisted? ? [id] : nil
+      key = respond_to?(:id) && id
+      key ? [key] : nil
     end
 
     # Returns a string representing the object's key suitable for use in URLs,
-- 
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