From 80989437dc1502f9194b0600941b6d70a3efa3b2 Mon Sep 17 00:00:00 2001
From: Josh Sharpe <josh.m.sharpe@gmail.com>
Date: Mon, 31 Aug 2009 12:50:27 -0500
Subject: I added this feature so that a Map of changed fields could be
 retrieved after a model had been saved. This is useful in the after_save
 callback when you need to know what fields changed. At present there is no
 way to do this other than have code in the before_save callback that takes a
 copy of the changes Map, which I thought was a bit messy.

Example.

  person = Person.find_by_name('bob')
  person.name = 'robert'
  person.changes # => {'name' => ['bob, 'robert']}
  person.save
  person.changes # => {}
  person.previous_changes # => {'name' => ['bob, 'robert']}
  person.reload
  person.previous_changes # => {}

Signed-off-by: Joshua Peek <josh@joshpeek.com>
---
 activerecord/test/cases/dirty_test.rb | 78 +++++++++++++++++++++++++++++++++++
 1 file changed, 78 insertions(+)

(limited to 'activerecord/test/cases/dirty_test.rb')

diff --git a/activerecord/test/cases/dirty_test.rb b/activerecord/test/cases/dirty_test.rb
index 74571d923a..f456d273fe 100644
--- a/activerecord/test/cases/dirty_test.rb
+++ b/activerecord/test/cases/dirty_test.rb
@@ -308,6 +308,84 @@ class DirtyTest < ActiveRecord::TestCase
     end
   end
 
+  def test_previous_changes
+    # original values should be in previous_changes
+    pirate = Pirate.new
+  
+    assert_equal Hash.new, pirate.previous_changes
+    pirate.catchphrase = "arrr"
+    pirate.save!
+  
+    assert_equal 4, pirate.previous_changes.size
+    assert_equal [nil, "arrr"], pirate.previous_changes['catchphrase']
+    assert_equal [nil, pirate.id], pirate.previous_changes['id']
+    assert_nil pirate.previous_changes['updated_on'][0]
+    assert_not_nil pirate.previous_changes['updated_on'][1]
+    assert_nil pirate.previous_changes['created_on'][0]
+    assert_not_nil pirate.previous_changes['created_on'][1]
+    assert !pirate.previous_changes.key?('parrot_id')
+  
+    # original values should be in previous_changes
+    pirate = Pirate.new
+  
+    assert_equal Hash.new, pirate.previous_changes
+    pirate.catchphrase = "arrr"
+    pirate.save
+  
+    assert_equal 4, pirate.previous_changes.size
+    assert_equal [nil, "arrr"], pirate.previous_changes['catchphrase']
+    assert_equal [nil, pirate.id], pirate.previous_changes['id']
+    assert pirate.previous_changes.include?('updated_on')
+    assert pirate.previous_changes.include?('created_on')
+    assert !pirate.previous_changes.key?('parrot_id')
+  
+    pirate.catchphrase = "Yar!!"
+    pirate.reload
+    assert_equal Hash.new, pirate.previous_changes
+
+    pirate = Pirate.find_by_catchphrase("arrr")
+    pirate.catchphrase = "Me Maties!"
+    pirate.save!
+
+    assert_equal 2, pirate.previous_changes.size
+    assert_equal ["arrr", "Me Maties!"], pirate.previous_changes['catchphrase']
+    assert_not_nil pirate.previous_changes['updated_on'][0]
+    assert_not_nil pirate.previous_changes['updated_on'][1]
+    assert !pirate.previous_changes.key?('parrot_id')
+    assert !pirate.previous_changes.key?('created_on')
+
+    pirate = Pirate.find_by_catchphrase("Me Maties!")
+    pirate.catchphrase = "Thar She Blows!"
+    pirate.save
+
+    assert_equal 2, pirate.previous_changes.size
+    assert_equal ["Me Maties!", "Thar She Blows!"], pirate.previous_changes['catchphrase']
+    assert_not_nil pirate.previous_changes['updated_on'][0]
+    assert_not_nil pirate.previous_changes['updated_on'][1]
+    assert !pirate.previous_changes.key?('parrot_id')
+    assert !pirate.previous_changes.key?('created_on')
+
+    pirate = Pirate.find_by_catchphrase("Thar She Blows!")
+    pirate.update_attributes(:catchphrase => "Ahoy!")
+
+    assert_equal 2, pirate.previous_changes.size
+    assert_equal ["Thar She Blows!", "Ahoy!"], pirate.previous_changes['catchphrase']
+    assert_not_nil pirate.previous_changes['updated_on'][0]
+    assert_not_nil pirate.previous_changes['updated_on'][1]
+    assert !pirate.previous_changes.key?('parrot_id')
+    assert !pirate.previous_changes.key?('created_on')
+
+    pirate = Pirate.find_by_catchphrase("Ahoy!")
+    pirate.update_attribute(:catchphrase, "Ninjas suck!")
+
+    assert_equal 2, pirate.previous_changes.size
+    assert_equal ["Ahoy!", "Ninjas suck!"], pirate.previous_changes['catchphrase']
+    assert_not_nil pirate.previous_changes['updated_on'][0]
+    assert_not_nil pirate.previous_changes['updated_on'][1]
+    assert !pirate.previous_changes.key?('parrot_id')
+    assert !pirate.previous_changes.key?('created_on')    
+  end
+
   private
     def with_partial_updates(klass, on = true)
       old = klass.partial_updates?
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