has_one maintains the association with separate after_create/after_update

This way parent models can get their own after_create and
after_update callbacks fired after has_one has done its job.

activerecord/CHANGELOG

@@ -1,5 +1,8 @@
 *Rails 3.1.0 (unreleased)*
 
+* has_one maintains the association with separate after_create/after_update instead
+  of a single after_save. [fxn]
+
 * The following code:
 
     Model.limit(10).scoping { Model.count }

activerecord/lib/active_record/autosave_association.rb

@@ -167,7 +167,16 @@ module ActiveRecord
           else
             if reflection.macro == :has_one
               define_method(save_method) { save_has_one_association(reflection) }
-              after_save save_method
+              # Configures two callbacks instead of a single after_save so that
+              # the model may rely on their execution order relative to its
+              # own callbacks.
+              #
+              # For example, given that after_creates run before after_saves, if
+              # we configured instead an after_save there would be no way to fire
+              # a custom after_create callback after the child association gets
+              # created.
+              after_create save_method
+              after_update save_method
             else
               define_method(save_method) { save_belongs_to_association(reflection) }
               before_save save_method

activerecord/test/cases/autosave_association_test.rb

@@ -17,6 +17,7 @@ require 'models/tag'
 require 'models/tagging'
 require 'models/treasure'
 require 'models/company'
+require 'models/eye'
 
 class TestAutosaveAssociationsInGeneral < ActiveRecord::TestCase
   def test_autosave_should_be_a_valid_option_for_has_one
@@ -170,6 +171,25 @@ class TestDefaultAutosaveAssociationOnAHasOneAssociation < ActiveRecord::TestCas
     firm.account = Account.find(:first).clone
     assert_queries(2) { firm.save! }
   end
+  
+  def test_callbacks_firing_order_on_create
+    eye = Eye.create(:iris_attributes => {:color => 'honey'})
+    assert_equal [true, false], eye.after_create_callbacks_stack
+  end
+
+  def test_callbacks_firing_order_on_update
+    eye = Eye.create(:iris_attributes => {:color => 'honey'})
+    eye.update_attributes(:iris_attributes => {:color => 'green'})
+    assert_equal [true, false], eye.after_update_callbacks_stack
+  end
+
+  def test_callbacks_firing_order_on_save
+    eye = Eye.create(:iris_attributes => {:color => 'honey'})
+    assert_equal [false, false], eye.after_save_callbacks_stack
+
+    eye.update_attributes(:iris_attributes => {:color => 'blue'})
+    assert_equal [false, false, false, false], eye.after_save_callbacks_stack
+  end
 end
 
 class TestDefaultAutosaveAssociationOnABelongsToAssociation < ActiveRecord::TestCase

activerecord/test/models/eye.rb

@@ -0,0 +1,37 @@
+class Eye < ActiveRecord::Base
+  attr_reader :after_create_callbacks_stack
+  attr_reader :after_update_callbacks_stack
+  attr_reader :after_save_callbacks_stack
+
+  # Callbacks configured before the ones has_one sets up.
+  after_create :trace_after_create
+  after_update :trace_after_update
+  after_save   :trace_after_save
+
+  has_one :iris
+  accepts_nested_attributes_for :iris
+
+  # Callbacks configured after the ones has_one sets up.
+  after_create :trace_after_create2
+  after_update :trace_after_update2
+  after_save   :trace_after_save2
+  
+  def trace_after_create
+    (@after_create_callbacks_stack ||= []) << iris.new_record?
+  end
+  alias trace_after_create2 trace_after_create
+
+  def trace_after_update
+    (@after_update_callbacks_stack ||= []) << iris.changed?
+  end
+  alias trace_after_update2 trace_after_update
+
+  def trace_after_save
+    (@after_save_callbacks_stack ||= []) << iris.changed?
+  end
+  alias trace_after_save2 trace_after_save
+end
+
+class Iris < ActiveRecord::Base
+  belongs_to :eye
+end

activerecord/test/schema/schema.rb

@@ -156,6 +156,11 @@ ActiveRecord::Schema.define do
     t.integer :company_id
   end
 
+  create_table :iris, :force => true do |t|
+    t.integer :eye
+    t.string  :color
+  end
+
   create_table :customers, :force => true do |t|
     t.string  :name
     t.integer :balance, :default => 0
@@ -194,6 +199,9 @@ ActiveRecord::Schema.define do
     t.integer :car_id
   end
 
+  create_table :eyes, :force => true do |t|
+  end
+
   create_table :tyres, :force => true do |t|
     t.integer :car_id
   end