From 7666f84f22cacfa193e9444c2264ffda8c7a8210 Mon Sep 17 00:00:00 2001
From: Stephen H. Gerstacker <stephen@shortround.net>
Date: Tue, 13 Jan 2009 20:10:03 -0500
Subject: [PATCH] Fixed bug with decimals of 0.0 being set as '' not counting as a change

---
 activerecord/lib/active_record/dirty.rb |    6 +++---
 activerecord/test/cases/dirty_test.rb   |   27 +++++++++++++++++++++++++++
 activerecord/test/schema/schema.rb      |    1 +
 3 files changed, 31 insertions(+), 3 deletions(-)

diff --git a/activerecord/lib/active_record/dirty.rb b/activerecord/lib/active_record/dirty.rb
index 4c899f5..a2eddaf 100644
--- a/activerecord/lib/active_record/dirty.rb
+++ b/activerecord/lib/active_record/dirty.rb
@@ -151,11 +151,11 @@ module ActiveRecord
 
       def field_changed?(attr, old, value)
         if column = column_for_attribute(attr)
-          if column.type == :integer && column.null && (old.nil? || old == 0) && value.blank?
-            # For nullable integer columns, NULL gets stored in database for blank (i.e. '') values.
+          if (column.type == :integer || column.type == :decimal) && column.null && (old.nil? || old == 0) && value.blank?
+            # For nullable integer and decimal columns, NULL gets stored in database for blank (i.e. '') values.
             # Hence we don't record it as a change if the value changes from nil to ''.
             # If an old value of 0 is set to '' we want this to get changed to nil as otherwise it'll
-            # be typecast back to 0 (''.to_i => 0)
+            # be typecast back to 0 (''.to_i => 0; ''.to_f => 0.0)
             value = nil
           else
             value = column.type_cast(value)
diff --git a/activerecord/test/cases/dirty_test.rb b/activerecord/test/cases/dirty_test.rb
index 10cdbdc..6d4bf34 100644
--- a/activerecord/test/cases/dirty_test.rb
+++ b/activerecord/test/cases/dirty_test.rb
@@ -107,6 +107,33 @@ class DirtyTest < ActiveRecord::TestCase
     assert_equal([0, nil], pirate.parrot_id_change)
   end
 
+  def test_decimal_zero_to_blank_marked_as_changed
+    pirate = Pirate.new
+    pirate.catchphrase = "Yarrrr, me hearties"
+    pirate.legs = 1.0
+    pirate.save
+
+    # check the change from 1 to ''
+    pirate = Pirate.find_by_catchphrase("Yarrrr, me hearties")
+    pirate.legs = ''
+    assert pirate.legs_changed?
+    assert_equal([1.0, nil], pirate.legs_change)
+    pirate.save
+
+    # check the change from nil to 0
+    pirate = Pirate.find_by_catchphrase("Yarrrr, me hearties")
+    pirate.legs = 0.0
+    assert pirate.legs_changed?
+    assert_equal([nil, 0.0], pirate.legs_change)
+    pirate.save
+
+    # check the change from 0 to ''
+    pirate = Pirate.find_by_catchphrase("Yarrrr, me hearties")
+    pirate.legs = ''
+    assert pirate.legs_changed?
+    assert_equal([0.0, nil], pirate.legs_change)
+  end
+
   def test_object_should_be_changed_if_any_attribute_is_changed
     pirate = Pirate.new
     assert !pirate.changed?
diff --git a/activerecord/test/schema/schema.rb b/activerecord/test/schema/schema.rb
index 8199cb8..6258827 100644
--- a/activerecord/test/schema/schema.rb
+++ b/activerecord/test/schema/schema.rb
@@ -312,6 +312,7 @@ ActiveRecord::Schema.define do
   create_table :pirates, :force => true do |t|
     t.column :catchphrase, :string
     t.column :parrot_id, :integer
+    t.column :legs, :decimal, :precision => 2, :scale => 1
     t.column :created_on, :datetime
     t.column :updated_on, :datetime
   end
-- 
1.6.1