1 files changed, 11 insertions, 10 deletions
diff --git a/activerecord/lib/active_record/associations/singular_association.rb b/activerecord/lib/active_record/associations/singular_association.rb
index 877ddf3ee1..ce1f2a5543 100644
--- a/activerecord/lib/active_record/associations/singular_association.rb
+++ b/activerecord/lib/active_record/associations/singular_association.rb
@@ -17,27 +17,28 @@ module ActiveRecord
         replace(record)
       end
 
-      def create(attributes = {}, options = {})
-        build(attributes, options).tap { |record| record.save }
+      def create(attributes = {}, options = {}, &block)
+        build(attributes, options, &block).tap { |record| record.save }
       end
 
-      def create!(attributes = {}, options = {})
-        build(attributes, options).tap { |record| record.save! }
+      def create!(attributes = {}, options = {}, &block)
+        build(attributes, options, &block).tap { |record| record.save! }
       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)
+        yield(record) if block_given?
         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