gistfile1.rb

#form 
<%= form_for [@site, @detail] do |f| %>
        <table id='amenities'>
          <thead>
            <th> Rank </th>
            <th> Value </th>
          </thead>
          <%= f.fields_for :amenities do |af| %>
            <tr>
              <td><%= af.text_field :rank, :size => 1 %></td>
              <td><%= af.text_field :value %></td>
              <td><%= link_to "[X]", amenity_path(af.object), :method => 'delete', :remote => true %></td>
            </tr>
          <% end %>
        </table>
        <a href='' class='add_amenity' id="<%= @detail.amenities.count %>">New Amenity</a>
        <br/>
        <%= f.submit "Save Changes" %>
      <% end %>

#controller action 
 def update
    @site = current_site
    if @site
      @detail = @site.detail
    else
      @detail = Detail.find(params[:id])
    end

    respond_to do |format|
      if @detail.update_attributes(params[:detail])
        format.html { redirect_to(site_detail_path(@site), :notice => 'Details Updated!') }
        format.js { render :layout => false}
      else
        format.html { redirect_to(site_detail_path(@site), :notice => 'Details Not Updated.') }
        format.xml { head :ok }
      end
    end
  end

#Routes
 resources :sites do
    resource :home_page
    resource :detail
    resource :calendar
    resources :galleries
  end

  resources :sites, :home_pages, :galleries, :pictures, :details, :amenities, :calendars, :reservations


  resource :detail do
    resources :amenities
  end

  resources :calendars do
    resources :reservations do
      get 'confirm', :on => :member
    end
  end