<% @user = MarkupUser.new %> <% form_for @user , '/demo1', :id => 'demo-fields-for' do |f| %> <%= f.text_field :gender %> <% fields_for @user.permission do |permission| %> <%= permission.check_box :can_edit %> <%= permission.check_box :can_delete %> <% end %> <% end %>