2 files changed, 36 insertions, 2 deletions
diff --git a/actionpack/lib/action_view/helpers/form_helper.rb b/actionpack/lib/action_view/helpers/form_helper.rb
index 4c050cae00..2bfb896633 100644
--- a/actionpack/lib/action_view/helpers/form_helper.rb
+++ b/actionpack/lib/action_view/helpers/form_helper.rb
@@ -639,8 +639,20 @@ module ActionView
         class_eval src, __FILE__, __LINE__
       end
 
-      def fields_for(name, *args, &block)
-        name = "#{object_name}[#{name}]"
+      def fields_for(record_or_name_or_array, *args, &block)
+        case record_or_name_or_array
+        when String, Symbol
+          name = "#{object_name}[#{record_or_name_or_array}]"
+        when Array
+          object = record_or_name_or_array.last
+          name = "#{object_name}[#{ActionController::RecordIdentifier.singular_class_name(object)}]"
+          args.unshift(object)
+        else
+          object = record_or_name_or_array
+          name = "#{object_name}[#{ActionController::RecordIdentifier.singular_class_name(object)}]"
+          args.unshift(object)
+        end
+        
         @template.fields_for(name, *args, &block)
       end
 
diff --git a/actionpack/test/template/form_helper_test.rb b/actionpack/test/template/form_helper_test.rb
index 136e6f1e83..37e3538b1e 100644
--- a/actionpack/test/template/form_helper_test.rb
+++ b/actionpack/test/template/form_helper_test.rb
@@ -489,6 +489,28 @@ class FormHelperTest < Test::Unit::TestCase
     assert_dom_equal expected, _erbout
   end
 
+  def test_form_for_and_fields_for_with_object
+    _erbout = ''
+
+    form_for(:post, @post, :html => { :id => 'create-post' }) do |post_form|
+      _erbout.concat post_form.text_field(:title)
+      _erbout.concat post_form.text_area(:body)
+
+      post_form.fields_for(@comment) do |comment_fields|
+        _erbout.concat comment_fields.text_field(:name)
+      end
+    end
+
+    expected = 
+      "<form action='http://www.example.com' id='create-post' method='post'>" +
+      "<input name='post[title]' size='30' type='text' id='post_title' value='Hello World' />" +
+      "<textarea name='post[body]' id='post_body' rows='20' cols='40'>Back to the hill and over it again!</textarea>" +
+      "<input name='post[comment][name]' type='text' id='post_comment_name' value='new comment' size='30' />" +
+      "</form>"
+
+    assert_dom_equal expected, _erbout
+  end
+
   class LabelledFormBuilder < ActionView::Helpers::FormBuilder
     (field_helpers - %w(hidden_field)).each do |selector|
       src = <<-END_SRC