From fec5bb1ada0313bc0f9ef4211fdfa370f9c90353 Mon Sep 17 00:00:00 2001
From: Paul Gillard <paulmgillard@gmail.com>
Date: Sat, 4 Jul 2009 11:50:16 +0100
Subject: [PATCH] Add method to reset attributes on dirty records

Added attribute_reset method which will reset an attribute to its original value should it have changed.
---
 activerecord/lib/active_record/dirty.rb |   29 ++++++++++++++++++++---------
 activerecord/test/cases/dirty_test.rb   |   10 ++++++++++
 2 files changed, 30 insertions(+), 9 deletions(-)

diff --git a/activerecord/lib/active_record/dirty.rb b/activerecord/lib/active_record/dirty.rb
index 178767e..b0f6692 100644
--- a/activerecord/lib/active_record/dirty.rb
+++ b/activerecord/lib/active_record/dirty.rb
@@ -2,17 +2,17 @@ module ActiveRecord
   # Track unsaved attribute changes.
   #
   # A newly instantiated object is unchanged:
-  #   person = Person.find_by_name('uncle bob')
+  #   person = Person.find_by_name('Uncle Bob')
   #   person.changed?       # => false
   #
   # Change the name:
   #   person.name = 'Bob'
   #   person.changed?       # => true
   #   person.name_changed?  # => true
-  #   person.name_was       # => 'uncle bob'
-  #   person.name_change    # => ['uncle bob', 'Bob']
+  #   person.name_was       # => 'Uncle Bob'
+  #   person.name_change    # => ['Uncle Bob', 'Bob']
   #   person.name = 'Bill'
-  #   person.name_change    # => ['uncle bob', 'Bill']
+  #   person.name_change    # => ['Uncle Bob', 'Bill']
   #
   # Save the changes:
   #   person.save
@@ -25,18 +25,24 @@ module ActiveRecord
   #   person.name_change    # => nil
   #
   # Which attributes have changed?
-  #   person.name = 'bob'
+  #   person.name = 'Bob'
   #   person.changed        # => ['name']
-  #   person.changes        # => { 'name' => ['Bill', 'bob'] }
+  #   person.changes        # => { 'name' => ['Bill', 'Bob'] }
+  #
+  # Resetting an attribute returns it to its original state:
+  #   person.name_reset     # => 'Bill'
+  #   person.changed?       # => false
+  #   person.name_changed?  # => false
+  #   person.name           # => 'Bill'
   #
   # Before modifying an attribute in-place:
   #   person.name_will_change!
-  #   person.name << 'by'
-  #   person.name_change    # => ['uncle bob', 'uncle bobby']
+  #   person.name << 'y'
+  #   person.name_change    # => ['Bill', 'Billy']
   module Dirty
     extend ActiveSupport::Concern
 
-    DIRTY_SUFFIXES = ['_changed?', '_change', '_will_change!', '_was']
+    DIRTY_SUFFIXES = ['_changed?', '_change', '_will_change!', '_was', '_reset']
 
     included do
       attribute_method_suffix *DIRTY_SUFFIXES
@@ -117,6 +123,11 @@ module ActiveRecord
       def attribute_was(attr)
         attribute_changed?(attr) ? changed_attributes[attr] : __send__(attr)
       end
+      
+      # Handle <tt>*_reset</tt> for +method_missing+.
+      def attribute_reset(attr)
+        attribute_changed?(attr) ? self[attr] = changed_attributes[attr] : __send__(attr)
+      end
 
       # Handle <tt>*_will_change!</tt> for +method_missing+.
       def attribute_will_change!(attr)
diff --git a/activerecord/test/cases/dirty_test.rb b/activerecord/test/cases/dirty_test.rb
index ac95bac..bc0eb80 100644
--- a/activerecord/test/cases/dirty_test.rb
+++ b/activerecord/test/cases/dirty_test.rb
@@ -62,6 +62,16 @@ class DirtyTest < ActiveRecord::TestCase
     assert_equal parrot.name_change, parrot.title_change
   end
 
+  def test_attribute_reset
+    pirate = Pirate.create!(:catchphrase => 'Yar!')
+    pirate.catchphrase = 'Ahoy!'
+
+    pirate.catchphrase_reset
+    assert_equal "Yar!", pirate.catchphrase
+    assert_equal Hash.new, pirate.changes
+    assert !pirate.catchphrase_changed?
+  end
+
   def test_nullable_number_not_marked_as_changed_if_new_value_is_blank
     pirate = Pirate.new
 
-- 
1.6.0.5