如何强制用户登录某个动作然后在以后执行。

 def update
    @article.attributes = params[:article]
    @article.save

    #store this article as a session variable
    session[:pending_article] = @article.body

    respond_with(@article, :location => article_url(@article))
  end

 def require_user
    unless current_user
      store_location
      flash[:notice] = \"You must be logged in to access this page\"
      redirect_to login_url
      return false
    end
  end

session[:article] = params[:article]

# this should take you back /articles/new,
# you may have to move your call to store_location 
# or manually set session[:return_to]
redirect_back_or_default 

def new
  @article = Article.new(session[:article] || {})
end