From eb22c51173f3ebe0f5a53f8bc57ebc74e4f0a824 Mon Sep 17 00:00:00 2001
From: Damien Mathieu <42@dmathieu.com>
Date: Sun, 26 Jun 2011 09:41:30 +0200
Subject: comparing different classes returns nil

---
 activerecord/lib/active_record/base.rb | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

(limited to 'activerecord/lib/active_record')

diff --git a/activerecord/lib/active_record/base.rb b/activerecord/lib/active_record/base.rb
index a2b5a3ec4f..e970445082 100644
--- a/activerecord/lib/active_record/base.rb
+++ b/activerecord/lib/active_record/base.rb
@@ -1806,7 +1806,11 @@ MSG
 
       # Allows sort on objects
       def <=>(other_object)
-        self.to_key <=> other_object.to_key
+        if other_object.is_a?(self.class)
+          self.to_key <=> other_object.to_key
+        else
+          nil
+        end
       end
 
       # Backport dup from 1.9 so that initialize_dup() gets called
-- 
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