升级 到 Rails 2.0 之前的准备动作

1. 创建文件：lib/tasks/rails.rake

desc "Checks your app and gently warns you if you are using deprecated code."
task :deprecated => :environment do
  deprecated = {
    '@params'    => 'Use params[] instead',
    '@session'   => 'Use session[] instead',
    '@flash'     => 'Use flash[] instead',
    '@request'   => 'Use request[] instead',
    '@env' => 'Use env[] instead',
    'find_all'   => 'Use find(:all) instead',
    'find_first' => 'Use find(:first) instead',
    'render_partial' => 'Use render :partial instead',
    'component'  => 'Use of components are frowned upon',
    'paginate'   => 'The default paginator is slow. Writing your own may be faster',
    'start_form_tag'   => 'Use form_for instead',
    'end_form_tag'   => 'Use form_for instead',
    ':post => true'   => 'Use :method => :post instead'
  }

  deprecated.each do |key, warning|
    puts '--> ' + key
    output = `cd '#{File.expand_path('app', RAILS_ROOT)}' && grep -n --exclude=*.svn* -r '#{key}' *`
    unless output =~ /^$/
      puts "  !! " + warning + " !!"
      puts '  ' + '.' * (warning.length + 6)
      puts output
    else
      puts "  Clean! Cheers for you!"
    end
    puts
  end
end

2. 执行 ＃railsapp>rake deprecated
  可以查看升级所需要更改的。即使现在不马上升级，到是可以随时注意一些写法。
 
3.使用插件 willpaginate
＃ install
＃railsapp>ruby /script/plugin install svn://errtheblog.com/svn/plugins/will_paginate

   # 替换以前的代码
@skus_pages,@skus = paginate :sku, :conditions => sql , :per_page => 30 , rder => "skuid"
替换为：
@skus = Sku.paginate :conditions => sql , :per_page => 30 , rder => "skuid",:page=>params["page"]
  记得要增加:page=>params["page"]，以前是不用的。

可能你会发现@skus_pages不见了，不用担心，它已经集成到了@skus中了
pages.current.previous => objs.previous_page
pages.current_page.number => objs.current_page
pages.current.next => objs.next_page

没有了pages.last ， 但是可以考虑使用 objs.page_count
没有了pages.first , 但是可以考虑直接使用 1

willpaginate 多执行了一次统计总记录条数的sql语句，所以可以直接使用objs.total_entries 获取总记录数量。


参考文档：
http://www.slashdotdash.net/articles/2007/12/03/rails-2-upgrade-notes
http://errtheblog.com/posts/56-im-paginating-again
http://www.iteye.com/news/567