From b5eb3215a68f94bb8cb20739366232c415744b83 Mon Sep 17 00:00:00 2001
From: bogdanvlviv <bogdanvlviv@gmail.com>
Date: Tue, 4 Apr 2017 20:23:51 +0300
Subject: [PATCH] Fix inconsistency with changed attributes when overriding AR
 attribute reader

---
 activemodel/lib/active_model/dirty.rb         | 12 ++++++++----
 activerecord/CHANGELOG.md                     |  4 ++++
 .../active_record/attribute_methods/dirty.rb  |  4 ++++
 activerecord/test/cases/dirty_test.rb         | 19 +++++++++++++++++++
 4 files changed, 35 insertions(+), 4 deletions(-)

diff --git a/activemodel/lib/active_model/dirty.rb b/activemodel/lib/active_model/dirty.rb
index 6e0af99ad7..37b51ad354 100644
--- a/activemodel/lib/active_model/dirty.rb
+++ b/activemodel/lib/active_model/dirty.rb
@@ -179,13 +179,13 @@ def changed_attributes
     # Handles <tt>*_changed?</tt> for +method_missing+.
     def attribute_changed?(attr, from: OPTION_NOT_GIVEN, to: OPTION_NOT_GIVEN) # :nodoc:
       !!changes_include?(attr) &&
-        (to == OPTION_NOT_GIVEN || to == __send__(attr)) &&
+        (to == OPTION_NOT_GIVEN || to == _attributes(attr)) &&
         (from == OPTION_NOT_GIVEN || from == changed_attributes[attr])
     end
 
     # Handles <tt>*_was</tt> for +method_missing+.
     def attribute_was(attr) # :nodoc:
-      attribute_changed?(attr) ? changed_attributes[attr] : __send__(attr)
+      attribute_changed?(attr) ? changed_attributes[attr] : _attributes(attr)
     end
 
     # Handles <tt>*_previously_changed?</tt> for +method_missing+.
@@ -226,7 +226,7 @@ def clear_changes_information # :doc:
 
       # Handles <tt>*_change</tt> for +method_missing+.
       def attribute_change(attr)
-        [changed_attributes[attr], __send__(attr)] if attribute_changed?(attr)
+        [changed_attributes[attr], _attributes(attr)] if attribute_changed?(attr)
       end
 
       # Handles <tt>*_previous_change</tt> for +method_missing+.
@@ -239,7 +239,7 @@ def attribute_will_change!(attr)
         return if attribute_changed?(attr)
 
         begin
-          value = __send__(attr)
+          value = _attributes(attr)
           value = value.duplicable? ? value.clone : value
         rescue TypeError, NoMethodError
         end
@@ -268,5 +268,9 @@ def set_attribute_was(attr, old_value)
       def clear_attribute_changes(attributes) # :doc:
         attributes_changed_by_setter.except!(*attributes)
       end
+
+      def _attributes(attr)
+        __send__(attr)
+      end
   end
 end
diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md
index 9e3b686bbb..ffe588b3c5 100644
--- a/activerecord/CHANGELOG.md
+++ b/activerecord/CHANGELOG.md
@@ -1,3 +1,7 @@
+*   Fix inconsistency with changed attributes when overriding AR attribute reader.
+
+    *bogdanvlviv*
+
 *   When calling the dynamic fixture accessor method with no arguments it now returns all fixtures of this type.
     Previously this method always returned an empty array.
 
diff --git a/activerecord/lib/active_record/attribute_methods/dirty.rb b/activerecord/lib/active_record/attribute_methods/dirty.rb
index bd5003d63a..63978cfb3e 100644
--- a/activerecord/lib/active_record/attribute_methods/dirty.rb
+++ b/activerecord/lib/active_record/attribute_methods/dirty.rb
@@ -328,6 +328,10 @@ def cache_changed_attributes
         def clear_changed_attributes_cache
           remove_instance_variable(:@cached_changed_attributes) if defined?(@cached_changed_attributes)
         end
+
+        def _attributes(attr)
+          _read_attribute(attr)
+        end
     end
   end
 end
diff --git a/activerecord/test/cases/dirty_test.rb b/activerecord/test/cases/dirty_test.rb
index f9eccfbda1..15d7a32e21 100644
--- a/activerecord/test/cases/dirty_test.rb
+++ b/activerecord/test/cases/dirty_test.rb
@@ -671,6 +671,25 @@ def test_datetime_attribute_doesnt_change_if_zone_is_modified_in_string
     assert binary.changed?
   end
 
+  test "changes is correct if override attribute reader" do
+    pirate = Pirate.create!(catchphrase: "arrrr")
+    def pirate.catchphrase
+      super.upcase
+    end
+
+    new_catchphrase = "arrrr matey!"
+
+    pirate.catchphrase = new_catchphrase
+    assert pirate.catchphrase_changed?
+
+    expected_changes = {
+      "catchphrase" => ["arrrr", new_catchphrase]
+    }
+
+    assert_equal new_catchphrase.upcase, pirate.catchphrase
+    assert_equal expected_changes, pirate.changes
+  end
+
   test "attribute_changed? doesn't compute in-place changes for unrelated attributes" do
     test_type_class = Class.new(ActiveRecord::Type::Value) do
       define_method(:changed_in_place?) do |*|
-- 
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