Rails routes mapping的一个奇怪的问题。顺便讨论一下如何做RESTful的paginate。

大家可以试验一下，在我的开发环境中会出现这个问题，不知道是不是只有我有问题。做法如下：
[list]

随便建立一个Rails工程；

随便生成一个scaffold_resource，比如map.resources :articles；

在routes.rb中加入如下代码，添加自己的routes mapping：

map.articles_paginate "articles;paginate", :controller => 'articles', :action => 'paginate', :conditions => { :method => :get }

在ArticlesController中声明方法paginate，然后随便以任何方式从view中调用这个url。

[/list]
我这里产生的结果是unknow action。这说明routes mapping已经起作用了，但是找不到paginate方法。

我知道我想要的mapping可以通过rails自带的方式实现，不需要自己写mapping。但是由于某些原因，我无法使用自带的实现方式。而且按道理我自己mapping也不应该有问题。请各位看看是怎么回事儿。

另外，顺便讨论一下RESTful的paginate应该如何实现。OK，我知道有人会说不要为了REST而REST，要用在合适的地方。这我同意，就是想讨论一下。如果结论就是REST不适合用在paginate上，那就不用呗。

该怎样实现还怎样实现
比如TopicsController中:

@post_pages, @posts = paginate(:posts, :per_page => 5, : order => 'posts.created_at', :conditions => ['posts.topic_id = ?', params[:id]])

show.rhtml中:

<% if @post_pages and @post_pages.current.next %>
  <%= link_to "Next page", { :page => @post_pages.current.next }  %>
<% end %>

<% if @post_pages and @post_pages.current.previous %>
  <%= link_to "Previous page", { :page => @post_pages.current.previous }  %>
<% end %>

<% if @post_pages.page_count > 1 %>
  <%= _('Pages:') %>
    <%= pagination_links @post_pages, :window_size => 10 %><% end %>

参考Beast的源码即可

那你能解释一下为什么我自己加的mapping会找不到action吗？谢谢。

我在自己的代码中使用paginate，

  def index
    # @articles = Article.find(:all)
    @article_pages, @articles = paginate :articles, :per_page => 1
    respond_to do |format|
      format.html # index.rhtml
      format.xml  { render :xml => @articles.to_xml }
    end
  end

但是出现了如下问题：
ArgumentError in ArticlesController#index

wrong number of arguments (2 for 0)

RAILS_ROOT: /Users/benben/Documents/workspace/playground/config/..
Application Trace | Framework Trace | Full Trace

#{RAILS_ROOT}/app/controllers/articles_controller.rb:6:in `paginate'
#{RAILS_ROOT}/app/controllers/articles_controller.rb:6:in `index'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/bin/mongrel_rails:16:in `load'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/bin/mongrel_rails:16

/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/base.rb:1095:in `send'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/base.rb:1095:in `perform_action_without_filters'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/filters.rb:632:in `call_filter'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/filters.rb:619:in `perform_action_without_benchmark'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/benchmarking.rb:66:in `perform_action_without_rescue'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/1.8/benchmark.rb:293:in `measure'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/benchmarking.rb:66:in `perform_action_without_rescue'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/rescue.rb:83:in `perform_action'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/base.rb:430:in `send'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/base.rb:430:in `process_without_filters'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/filters.rb:624:in `process_without_session_management_support'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/session_management.rb:114:in `process'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/base.rb:330:in `process'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/rails-1.2.3/lib/dispatcher.rb:41:in `dispatch'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel/rails.rb:78:in `process'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel/rails.rb:76:in `synchronize'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel/rails.rb:76:in `process'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel.rb:618:in `process_client'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel.rb:617:in `each'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel.rb:617:in `process_client'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel.rb:736:in `run'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel.rb:736:in `initialize'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel.rb:736:in `new'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel.rb:736:in `run'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel.rb:720:in `initialize'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel.rb:720:in `new'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel.rb:720:in `run'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel/configurator.rb:271:in `run'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel/configurator.rb:270:in `each'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel/configurator.rb:270:in `run'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/mongrel-1.0.1/bin/mongrel_rails:127:in `run'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel/command.rb:211:in `run'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/mongrel-1.0.1/bin/mongrel_rails:243

#{RAILS_ROOT}/app/controllers/articles_controller.rb:6:in `paginate'
#{RAILS_ROOT}/app/controllers/articles_controller.rb:6:in `index'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/base.rb:1095:in `send'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/base.rb:1095:in `perform_action_without_filters'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/filters.rb:632:in `call_filter'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/filters.rb:619:in `perform_action_without_benchmark'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/benchmarking.rb:66:in `perform_action_without_rescue'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/1.8/benchmark.rb:293:in `measure'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/benchmarking.rb:66:in `perform_action_without_rescue'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/rescue.rb:83:in `perform_action'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/base.rb:430:in `send'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/base.rb:430:in `process_without_filters'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/filters.rb:624:in `process_without_session_management_support'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/session_management.rb:114:in `process'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/base.rb:330:in `process'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/rails-1.2.3/lib/dispatcher.rb:41:in `dispatch'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel/rails.rb:78:in `process'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel/rails.rb:76:in `synchronize'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel/rails.rb:76:in `process'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel.rb:618:in `process_client'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel.rb:617:in `each'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel.rb:617:in `process_client'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel.rb:736:in `run'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel.rb:736:in `initialize'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel.rb:736:in `new'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel.rb:736:in `run'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel.rb:720:in `initialize'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel.rb:720:in `new'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel.rb:720:in `run'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel/configurator.rb:271:in `run'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel/configurator.rb:270:in `each'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel/configurator.rb:270:in `run'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/mongrel-1.0.1/bin/mongrel_rails:127:in `run'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel/command.rb:211:in `run'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/lib/ruby/gems/1.8/gems/mongrel-1.0.1/bin/mongrel_rails:243
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/bin/mongrel_rails:16:in `load'
/Applications/Locomotive2/Bundles/standardRailsMar2007.locobundle/powerpc/bin/mongrel_rails:16

Request

Parameters: None

Show session dump

---
flash: !map:ActionController::Flash::FlashHash {}


Response
Headers: {"cookie"=>[], "Cache-Control"=>"no-cache"}

现在更奇怪，连这样的标准写法都不行了...

map.resources :articles, :collection => { :paginate => :get }

找到原因了，paginate是ActionController::Pagination中的一个方法的名字，在ActionController中是hidden action。换个名字就好了，哎。