gistfile1.rb

# Rails Monkey Patch for fields_for with nested attributes.
# Allows an array to be supplied to a nested fields_for call instead
# of just a single object.
module ActionView
  module Helpers
    class FormBuilder
      def fields_for_with_nested_attributes(association_name, args, block)
        name = "#{object_name}[#{association_name}_attributes]"

        obj_arg = args.first
        if obj_arg.respond_to?(:new_record?)
          if @object.send(association_name).is_a?(Array)
            records = [obj_arg]
          else
            records = obj_arg
          end 
        elsif obj_arg.is_a?(Array) && obj_arg.first.respond_to?(:new_record?)
          records = obj_arg
        else
          records = @object.send(association_name)
        end 

        if records.is_a?(Array)
          explicit_child_index = args.last[:child_index] if args.last.is_a?(Hash)

          records.map do |child|
            fields_for_nested_model("#{name}[#{explicit_child_index || nested_child_index}]", child, args, block)
          end.join
        else
          fields_for_nested_model(name, records, args, block)
        end 
      end 
    end 
  end 
end