从Rails2到Rails3

我们来看下rails3相比rails2, 进步在哪里, 优势又在什么地方.

 

1. 脚本命令

旧的命令                                      新的用法

script/generate                          rails g

script/console                            rails c

script/server                              rails s

script/dbconsole                        rails db

 

2. 配置文件

rails2: config/environment.rb

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Rails::Initializer.run do |config|       config.load_paths += %W( #{RAILS_ROOT}/extras )       config.gem "bj"      config.gem "sqlite3-ruby", :lib => "sqlite3"      config.gem "aws-s3", :lib => "aws/s3"     config.plugins = [ :exception_notification ]      config.time_zone = 'UTC'  end

rails3:config/application.rb

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module APP_NAME       class Application < Rails::Application           config.load_paths += %W( #{RAILS_ROOT}/extras )           config.plugins = [ :exception_notification ]           config.time_zone = 'UTC'      end  end

这样就变成了一种架构式的应用, 我们可以根据方便的对config进行操作

 

3. 路由

在rails3中, 已经的路由可以继续工作, 而新的路由方式更加简洁.

在 rails2 中:

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map.resources :posts do |post|       post.resources :comments  end

而在rails3中, 表达更为形象:
 

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resources :posts do      resources :comments  end

对于一些复杂的路由, rails2:

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post.resources :comments,                    :member => { :preview => :post },                   :collection => { :archived => :get }

 在rails3中可以这样表达:

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resources :comments do      member do          post :preview      end      collection do          get :archived      end  end

不够简洁? 我们还可以这样做:

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resources :comments do      post :preview, :on => :member      get :archived, :on => :collection  end

对于基本路由, rails2:

1	map.connect 'login', :controller => 'session', :action => 'new'

 那么在rails3中:

1	match 'login' => 'session#new'

对于具名路由, rails2:

1	map.login 'login', :controller => 'session', :action => 'new'

在rails3中:

1	match 'login' => 'session#new', :as => :login

对于程序根路由, rails2:

1	map.root :controller => 'users', :action => 'index'

rails3:

1	root :to => 'users#index'

对于遗留路由, rails2:

1 2	map.connect ':controller/:action/:id'  map.connect ':controller/:action/:id.:format'

 那么在rails3中写法更优雅:

1	match ':controller(/:action(/:id(.:format)))'

对于路由参数, rals2:

1	map.connect '/articles/:year/:month/:day', :controller => 'posts', :action => 'index'

rails3:
 

1	match '/articles/:year/:month/:day' => "posts#index"

那么对于存档请求, 比如rails2:

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map.connect '/articles/:year/:month/:day', :controller => 'posts', :action => 'index'  map.connect '/articles/:year/:month', :controller => 'posts', :action => 'index'  map.connect '/articles/:year', :controller => 'posts', :action => 'index'

在rails3中:
 

1	match '/articles(/:year(/:month(/:day)))' => "posts#index"

指定请求方式, rails2:

1 2	map.connect '/articles/:year', :controller => 'posts', :action => 'index',   :conditions => {:method => :get}

在rails3中:
 

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match '/articles/:year' => "posts#index", :via => :get  #或者更简单的:   get '/articles/:year' => "posts#index"

对于跳转, rails3:

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match 'signin', :to => redirect("/login")   match 'users/:name', :to => redirect {|params| "/#{params[:name]}" }   match 'google' => redirect('http://www.google.com/')

路由约束: rails2中实际上使用了 :requirements 符号

1 2	map.connect '/:year', :controller => 'posts', :action => 'index',                                       :requirements => { :year => /\d{4}/ }

在rails3中:
 

1	match '/:year' => "posts#index", :constraints => {:year => /\d{4}/}

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:constraints => { :user_agent => /iphone/ }   :constraints => { :ip => /192\.168\.1\.\d{1,3}/ }   constraints(:host => /localhost/) do      resources :posts  end  constraints IpRestrictor do     get 'admin/accounts' => "queenbee#accounts"  end

对于Rack应用, rails3:

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get 'hello' => proc { |env| [200, {}, "Hello Rack"] }   get 'rack_endpoint' => PostsController.action(:index)   get 'rack_app' => CustomRackApp

4. Bundler与ActionController

一个典型的rails应用, 我们一般需要在 environment.rb 指定你的 gems:

1 2	config.gem "haml"  config.gem "chronic", :version => '0.2.3'

然后我们运行 $ rake gems:install, 该命令会取得并下载然后安装编译这些gems到你的系统RubyGems目录中.

之后我们运行 $ rake gems:unpack:dependencise, 把这些gem打包到你应用程序的vendor/gems目录中去.

 

这样做产生的问题:

1. 它直接绑定到Rails中

2. 没有从本质上解决依赖问题

3. 运行时容易发生冲突

 

在rails3中, 使用了 bundle 命令:

直接在你的 gemfile 中指定你的 gem

1 2	gem "haml"  gem "chronic", '0.2.3'

然后运行 $ bundle, 该命令会会取得并下载然后安装编译这些gems

然后运行 $ bundle package 把gem源移到/vendor/cache中去.

这样rails应用中的gem与系统中的gem就不会相冲突.

一般的控制器语法:

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class UsersController < ApplicationController       def index          @users = User.all           respond_to do |format|               format.html               format.xml { render :xml => @users.to_xml }            end      end         def show          @user = User.find(params[:id])           respond_to do |format|               format.html # show.html.erb               format.xml { render :xml => @user }           end      end      ....

改进的语法:

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class UsersController < ApplicationController       respond_to :html, :xml, :json      def index           @users = User.all          respond_with(@users)       end     def show          @user = User.find(params[:id])           respond_with(@user)       end  ....

5. ActionMailer

rails2:  $ script/generate mailer UserMailer welcome forgot_password

这将创建 app/models/user_mailer.rb

那么在rails3中: $ rails g mailer UserMailer welcome forgot_password

这将创建 app/mailers/user_mailer.rb

 

在实现部分, rails2:

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def welcome(user, subdomain)       subject 'Welcome to TestApp'     recipients user.email       from '[e-mail]'      body :user => user, :subdomain => subdomain   end

1	UserMailer.deliver_welcome(user, subdomain)

在rails3中:

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def welcome(user, subdomain)       @user = user       @subdomain = subdomain       mail(:from => "[e-mail]",               :to => user.email,              :subject => "Welcome to TestApp")   end

1	UserMailer.welcome(user, subdomain).deliver

相比rails2, 我们在rails3下实现一个mail要简单的多:

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class UserMailer < ActionMailer::Base       default :from => "[e-mail]",                   :reply_to => "[e-mail]",                  "X-Time-Code" => Time.now.to_i.to_s       def welcome(user, subdomain)           @user = user           @subdomain = subdomain           attachments['test.pdf'] = File.read("#{Rails.root}/public/test.pdf")           mail(:to => @user.email, :subject => "Welcome to TestApp") do |format|               format.html { render 'other_html_welcome' }               format.text { render 'other_text_welcome' }           end      end  end

6. ActiveRelation 以及 ActiveModel

在rails2中, 我们经常使用下面的方法来进行查询:

1	@posts = Post.find(:all, :conditions => {:published => true})

该方式将立即查询数据库然后返回Posts数组

 

而在rails3中:

1	@posts = Post.where(:published => true)

该方法不会查询数据库, 仅仅返回一个 ActiveRecord::Relation 对象, 然后:
 

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@posts = Post.where(:published => true)   if params[:order]      @posts = @posts.order(params[:order])   end  @posts.each do |p|       ...                 #在这里进行查询, 实现延迟加载   end

对于命名范围, 在rails2中:

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class Post < ActiveRecord::Base       default_scope :order => 'title'      named_scope :published, :conditions => {:published => true}       named_scope :unpublished, :conditions => {:published => false}   end

而在rails3中:

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class Post < ActiveRecord::Base       default_scope order('title')       scope :published, where(:published => true)       scope :unpublished, where(:published => false)   end

对于查找方法, rails2:
 

1	Post.find(:all, :conditions => {:author => "Joe"}, :includes => :comments, :order => "title", :limit => 10)

在rails3:

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1 2	Post.find(:all, :conditions => {:author => "Joe"}, :includes => :comments, :order => "title", :limit => 10)

7. 跨站点脚本(XSS)

在rails2中, 一般我们输入一段文本的时候, 我们往往会这样写: <%= h @post.body %>

那么在rails3中, <%= @post.body %> 默认输出的是一段safe html, 如果想输出XSS, 可以在前面加上 raw