# File lib/action_view/helpers/form_helper.rb, line 145 def fields_for(object_name, *args, &block) raise ArgumentError, "Missing block" unless block_given? options = args.last.is_a?(Hash) ? args.pop : {} object = args.first builder = options[:builder] || ActionView::Base.default_form_builder yield builder.new(object_name, object, self, options, block) end