Pass the attribute and option hashes to build_association

The build_association method was added as an API for plugins
to hook into in 1398db0. This commit restores this API and the
ability to override class.new to return a subclass based on
a virtual attribute in the attributes hash.

3 files changed, 42 insertions, 0 deletions

diff --git a/activerecord/test/cases/associations/has_many_associations_test.rb b/activerecord/test/cases/associations/has_many_associations_test.rb
index 0e33fa9c8e..522ac56d82 100644
--- a/activerecord/test/cases/associations/has_many_associations_test.rb
+++ b/activerecord/test/cases/associations/has_many_associations_test.rb
@@ -1455,4 +1455,17 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
 
     assert_equal "RED!", car.bulbs.to_a.first.color
   end
+
+  def test_new_is_called_with_attributes_and_options
+    car = Car.create(:name => 'honda')
+
+    bulb = car.bulbs.build
+    assert_equal Bulb, bulb.class
+
+    bulb = car.bulbs.build(:bulb_type => :custom)
+    assert_equal Bulb, bulb.class
+
+    bulb = car.bulbs.build({ :bulb_type => :custom }, :as => :admin)
+    assert_equal CustomBulb, bulb.class
+  end
 end
diff --git a/activerecord/test/cases/associations/has_one_associations_test.rb b/activerecord/test/cases/associations/has_one_associations_test.rb
index 356a4a7a09..38e622f90f 100644
--- a/activerecord/test/cases/associations/has_one_associations_test.rb
+++ b/activerecord/test/cases/associations/has_one_associations_test.rb
@@ -410,4 +410,20 @@ class HasOneAssociationsTest < ActiveRecord::TestCase
     bulb = car.create_frickinawesome_bulb(:frickinawesome => false)
     assert_equal true, bulb.frickinawesome?
   end
+
+  def test_new_is_called_with_attributes_and_options
+    car = Car.create(:name => 'honda')
+
+    bulb = car.build_bulb
+    assert_equal Bulb, bulb.class
+
+    bulb = car.build_bulb
+    assert_equal Bulb, bulb.class
+
+    bulb = car.build_bulb(:bulb_type => :custom)
+    assert_equal Bulb, bulb.class
+
+    bulb = car.build_bulb({ :bulb_type => :custom }, :as => :admin)
+    assert_equal CustomBulb, bulb.class
+  end
 end
diff --git a/activerecord/test/models/bulb.rb b/activerecord/test/models/bulb.rb
index 7d90963720..0dcc8d5970 100644
--- a/activerecord/test/models/bulb.rb
+++ b/activerecord/test/models/bulb.rb
@@ -15,4 +15,17 @@ class Bulb < ActiveRecord::Base
     self[:color] = color.upcase + "!"
   end
 
+  def self.new(attributes = {}, options = {}, &block)
+    bulb_type = (attributes || {}).delete(:bulb_type)
+
+    if options && options[:as] == :admin && bulb_type.present?
+      bulb_class = "#{bulb_type.to_s.camelize}Bulb".constantize
+      bulb_class.new(attributes, options, &block)
+    else
+      super
+    end
+  end
 end
+
+class CustomBulb < Bulb
+end
\ No newline at end of file