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.

5 files changed, 54 insertions, 8 deletions

diff --git a/activerecord/lib/active_record/associations/collection_association.rb b/activerecord/lib/active_record/associations/collection_association.rb
index 525ac65722..902ad8cb64 100644
--- a/activerecord/lib/active_record/associations/collection_association.rb
+++ b/activerecord/lib/active_record/associations/collection_association.rb
@@ -423,9 +423,13 @@ module ActiveRecord
           raise NotImplementedError
         end
 
+        def create_scope
+          scoped.scope_for_create.stringify_keys
+        end
+
         def build_record(attributes, options)
-          record = reflection.build_association
-          record.assign_attributes(scoped.scope_for_create, :without_protection => true)
+          record = reflection.build_association(attributes, options)
+          record.assign_attributes(create_scope.except(*record.changed), :without_protection => true)
           record.assign_attributes(attributes, options)
           record
         end
diff --git a/activerecord/lib/active_record/associations/singular_association.rb b/activerecord/lib/active_record/associations/singular_association.rb
index 877ddf3ee1..44dbe984d4 100644
--- a/activerecord/lib/active_record/associations/singular_association.rb
+++ b/activerecord/lib/active_record/associations/singular_association.rb
@@ -26,18 +26,18 @@ module ActiveRecord
       end
 
       def build(attributes = {}, options = {})
-        record = reflection.build_association
-        record.assign_attributes(
-          scoped.scope_for_create.except(klass.primary_key),
-          :without_protection => true
-        )
-        record.assign_attributes(attributes, options)
+        record = reflection.build_association(attributes, options)
+        record.assign_attributes(create_scope.except(*record.changed), :without_protection => true)
         set_new_record(record)
         record
       end
 
       private
 
+        def create_scope
+          scoped.scope_for_create.stringify_keys.except(klass.primary_key)
+        end
+
         def find_target
           scoped.first.tap { |record| set_inverse_instance(record) }
         end
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
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