Rails Automatically Save a Draft of a Form

Gmail里的Ajax自动保存草稿在Rails里的实现
首先在layout里引入Javascript标签
[coce]
<%= javascript_include_tag :defaults %>
posts_controller.rb

def new
  if request.get?
    @post = session[:post_draft] || Post.new
  else
    @post = Post.create(params:post])
    session[:post_draft] = nil
    redirecto_to :action => 'list'
  end
end

def save_draft
  session[:post_draft] = Post.new(params[:post])
  render :text => "<i>Draft saved at #{Time.now}</i>"
end

def new   if request.get?     @post = session[:post_draft] || Post.new   else     @post = Post.create(params:post])     session[:post_draft] = nil     redirecto_to :action => 'list'   end end  def save_draft   session[:post_draft] = Post.new(params[:post])   render :text => "<i>Draft saved at #{Time.now}</i>" end 

posts/new.rhtml

<% form_for :post, @post,
            :url => {:action => "new" },
            :html => {:id => 'post_form'} do |f| %>
  Title: <%= f.text_field :title %><br/>
  Body: <%= f.text_area :body %><br/>
  <%= submit_tag "Save Post" %>
<% end %>
<div id='draft-message' style='color:read;'>
</div>
<%= observe_form 'post_form',
                 :url => {:action => 'save_draft'},
                 :update => 'draft-message',
                 :frequency => 30 %>