Fix #3837.

We also need to time zone convert time zone aware attributes when
accessed via read_attribute, not only when via direct access.

activerecord/lib/active_record/attribute_methods/time_zone_conversion.rb

@@ -16,22 +16,16 @@ module TimeZoneConversion
 
       module ClassMethods
         protected
-          # Defined for all +datetime+ and +timestamp+ attributes when +time_zone_aware_attributes+ are enabled.
-          # This enhanced read method automatically converts the UTC time stored in the database to the time
+          # The enhanced read method automatically converts the UTC time stored in the database to the time
           # zone stored in Time.zone.
-          def internal_attribute_access_code(attr_name, cast_code)
+          def attribute_cast_code(attr_name)
             column = columns_hash[attr_name]
 
             if create_time_zone_conversion_attribute?(attr_name, column)
-              super(attr_name, "(v=#{column.type_cast_code('v')}) && #{cast_code}")
-            else
-              super
-            end
-          end
+              typecast             = "v = #{super}"
+              time_zone_conversion = "v.acts_like?(:time) ? v.in_time_zone : v"
 
-          def attribute_cast_code(attr_name)
-            if create_time_zone_conversion_attribute?(attr_name, columns_hash[attr_name])
-              "(v.acts_like?(:time) ? v.in_time_zone : v)"
+              "((#{typecast}) && (#{time_zone_conversion}))"
             else
               super
             end

activerecord/test/cases/attribute_methods_test.rb

@@ -553,6 +553,17 @@ def test_setting_time_zone_aware_attribute_in_other_time_zone
     end
   end
 
+  def test_setting_time_zone_aware_read_attribute
+    utc_time = Time.utc(2008, 1, 1)
+    cst_time = utc_time.in_time_zone("Central Time (US & Canada)")
+    in_time_zone "Pacific Time (US & Canada)" do
+      record = @target.create(:written_on => cst_time).reload
+      assert_equal utc_time, record[:written_on]
+      assert_equal ActiveSupport::TimeZone["Pacific Time (US & Canada)"], record[:written_on].time_zone
+      assert_equal Time.utc(2007, 12, 31, 16), record[:written_on].time
+    end
+  end
+
   def test_setting_time_zone_aware_attribute_with_string
     utc_time = Time.utc(2008, 1, 1)
     (-11..13).each do |timezone_offset|
@@ -572,6 +583,7 @@ def test_setting_time_zone_aware_attribute_to_blank_string_returns_nil
       record   = @target.new
       record.written_on = ' '
       assert_nil record.written_on
+      assert_nil record[:written_on]
     end
   end