出处: oreilly
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趁着上班前写一段 @@
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那么从前面的教程中我们学习了如何创建一个简单的博客应用, 我个人觉得无论你是新手还是从rails2过来, rails3还是比较容易上手的, 现在我们就来看下rails3相比rails2, 进步在哪里, 优势又在什么地方. (本来这章打算写ujs的, 无奈工作繁忙只能推到周日了)
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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
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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
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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
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?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
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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:
map.resources :posts do |post|
post.resources :comments
end
?而在rails3中, 表达更为形象:
resources :posts do
resources :comments
end
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对于一些复杂的路由, rails2:
post.resources :comments,
:member => { :preview => :post },
:collection => { :archived => :get }
?在rails3中可以这样表达:
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:
resources :comments do
post :preview, :on => :member
get :archived, :on => :collection
end
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对于基本路由, rails2:
map.connect 'login', :controller => 'session', :action => 'new'
?那么在rails3中:
match 'login' => 'session#new'
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对于具名路由, rails2:
map.login 'login', :controller => 'session', :action => 'new'
在rails3中:
match 'login' => 'session#new', :as => :login
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对于程序根路由, rails2:
map.root :controller => 'users', :action => 'index'
?rails3:
root :to => 'users#index'
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对于遗留路由, rails2:
map.connect ':controller/:action/:id' map.connect ':controller/:action/:id.:format'
?那么在rails3中写法更优雅:
match ':controller(/:action(/:id(.:format)))'
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对于路由参数, rals2:
map.connect '/articles/:year/:month/:day', :controller => 'posts', :action => 'index'
?rails3:
match '/articles/:year/:month/:day' => "posts#index"
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那么对于存档请求, 比如rails2:
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:
match '/articles(/:year(/:month(/:day)))' => "posts#index"
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指定请求方式, rails2:
map.connect '/articles/:year', :controller => 'posts', :action => 'index',
:conditions => {:method => :get}
?在rails3中:
match '/articles/:year' => "posts#index", :via => :get #或者更简单的: get '/articles/:year' => "posts#index"
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对于跳转, rails3:
match 'signin', :to => redirect("/login")
match 'users/:name', :to => redirect {|params| "/#{params[:name]}" }
match 'google' => redirect('http://www.google.com/')
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路由约束: rails2中实际上使用了 :requirements 符号
map.connect '/:year', :controller => 'posts', :action => 'index',
:requirements => { :year => /\d{4}/ }
?在rails3中:
match '/:year' => "posts#index", :constraints => {:year => /\d{4}/}
: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
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对于Rack应用, rails3:
get 'hello' => proc { |env| [200, {}, "Hello Rack"] }
get 'rack_endpoint' => PostsController.action(:index)
get 'rack_app' => CustomRackApp
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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:
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.
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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
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在rails3中, 使用了 bundle 命令:
直接在你的 gemfile 中指定你的 gem
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.
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这样rails应用中的gem与系统中的gem就不会相冲突.
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一般的控制器语法:
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
...
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改进的语法:
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
...
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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
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在实现部分, rails2:
def welcome(user, subdomain)
subject 'Welcome to TestApp'
recipients user.email
from 'admin@testapp.com'
body :user => user, :subdomain => subdomain
end
UserMailer.deliver_welcome(user, subdomain)
在rails3中:
def welcome(user, subdomain)
@user = user
@subdomain = subdomain
mail(:from => "admin@testapp.com",
:to => user.email,
:subject => "Welcome to TestApp")
end
UserMailer.welcome(user, subdomain).deliver
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相比rails2, 我们在rails3下实现一个mail要简单的多:
class UserMailer < ActionMailer::Base
default :from => "admin@testapp.com",
:reply_to => "noreply@testapp.com",
"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?
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6. ActiveRelation 以及 ActiveModel
在rails2中, 我们经常使用下面的方法来进行查询:
@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
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而在rails3中:
@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:
@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
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对于命名范围, 在rails2中:
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:
class Post < ActiveRecord::Base
default_scope order('title')
scope :published, where(:published => true)
scope :unpublished, where(:published => false)
end
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对于查找方法, rails2:
Post.find(:all, :conditions => {:author => "Joe"}, :includes => :comments, :order => "title", :limit => 10)
?在rails3:
Post.where(:author => "Joe").include(:comments).order(:title).limit(10).all
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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
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