Allowing an object to be passed explicitly to a fields_for with nested_attributes on one-to-one associations

Signed-off-by: Michael Koziarski <michael@koziarski.com>
[#1849 state:committed]

2 files changed, 11 insertions, 1 deletions

diff --git a/actionpack/lib/action_view/helpers/form_helper.rb b/actionpack/lib/action_view/helpers/form_helper.rb
index 2ac2427884..0651f75cfb 100644
--- a/actionpack/lib/action_view/helpers/form_helper.rb
+++ b/actionpack/lib/action_view/helpers/form_helper.rb
@@ -971,7 +971,8 @@ module ActionView
               @template.fields_for(child_name, child, *args, &block)
             end.join
           else
-            @template.fields_for(name, association, *args, &block)
+            object = args.first.respond_to?(:new_record?) ? args.first : association
+            @template.fields_for(name, object, *args, &block)
           end
         end
 
diff --git a/actionpack/test/template/form_helper_test.rb b/actionpack/test/template/form_helper_test.rb
index 33a542af7e..b7ea2c0176 100644
--- a/actionpack/test/template/form_helper_test.rb
+++ b/actionpack/test/template/form_helper_test.rb
@@ -586,6 +586,15 @@ class FormHelperTest < ActionView::TestCase
     assert_dom_equal expected, output_buffer
   end
 
+  def test_nested_fields_for_with_explicitly_passed_object_on_a_nested_attributes_one_to_one_association
+    form_for(:post, @post) do |f|
+      f.fields_for(:author, Author.new(123)) do |af|
+        assert_not_nil af.object
+        assert_equal 123, af.object.id
+      end
+    end
+  end
+
   def test_nested_fields_for_with_an_existing_record_on_a_nested_attributes_one_to_one_association
     @post.author = Author.new(321)