Add method fields_for_with_index to FormHelper

1 files changed, 19 insertions, 0 deletions

diff --git a/actionpack/lib/action_view/helpers/form_helper.rb b/actionpack/lib/action_view/helpers/form_helper.rb
index 07e2c8d341..319aa36698 100644
--- a/actionpack/lib/action_view/helpers/form_helper.rb
+++ b/actionpack/lib/action_view/helpers/form_helper.rb
@@ -555,6 +555,19 @@ module ActionView
       #     ...
       #   <% end %>
       #
+      # In addition, you may want to have access to the current iteration index.
+      # In that case, you can use a similar method called fields_for_with_index
+      # which receives a block with an extra parameter:
+      #
+      #   <%= form_for @person do |person_form| %>
+      #     ...
+      #     <%= person_form.fields_for_with_index :projects do |project_fields, index| %>
+      #       Position: <%= index %>
+      #       Name: <%= project_fields.text_field :name %>
+      #     <% end %>
+      #     ...
+      #   <% end %>
+      #
       # When projects is already an association on Person you can use
       # +accepts_nested_attributes_for+ to define the writer method for you:
       #
@@ -1216,6 +1229,12 @@ module ActionView
         RUBY_EVAL
       end
 
+      def fields_for_with_index(record_name, record_object = nil, fields_options = {}, &block)
+        index = fields_options[:index] || options[:child_index] || nested_child_index(@object_name)
+        block_with_index = Proc.new{ |obj| block.call(obj, index) }
+        fields_for(record_name, record_object, fields_options, &block_with_index)
+      end
+
       def fields_for(record_name, record_object = nil, fields_options = {}, &block)
         fields_options, record_object = record_object, nil if record_object.is_a?(Hash)
         fields_options[:builder] ||= options[:builder]