Revert "to_key on a destroyed model should return nil". Closes #2440

This reverts commit c5448721b5054b8a467958d60427fdee15eac604.

2 files changed, 3 insertions, 4 deletions

diff --git a/activerecord/lib/active_record/attribute_methods/primary_key.rb b/activerecord/lib/active_record/attribute_methods/primary_key.rb
index 8bd898d126..ed71b5e7d4 100644
--- a/activerecord/lib/active_record/attribute_methods/primary_key.rb
+++ b/activerecord/lib/active_record/attribute_methods/primary_key.rb
@@ -3,11 +3,10 @@ module ActiveRecord
     module PrimaryKey
       extend ActiveSupport::Concern
 
-      # Returns this record's primary key value wrapped in an Array or nil if
-      # the record is not persisted? or has just been destroyed.
+      # Returns this record's primary key value wrapped in an Array if one is available
       def to_key
         key = send(self.class.primary_key)
-        persisted? && key ? [key] : nil
+        [key] if key
       end
 
       module ClassMethods
diff --git a/activerecord/test/cases/primary_keys_test.rb b/activerecord/test/cases/primary_keys_test.rb
index 7e3da145e5..05a41d8a0a 100644
--- a/activerecord/test/cases/primary_keys_test.rb
+++ b/activerecord/test/cases/primary_keys_test.rb
@@ -26,7 +26,7 @@ class PrimaryKeysTest < ActiveRecord::TestCase
   def test_to_key_with_primary_key_after_destroy
     topic = Topic.find(1)
     topic.destroy
-    assert_equal nil, topic.to_key
+    assert_equal [1], topic.to_key
   end
 
   def test_integer_key