文章出处：http://shuaigelingfei.iteye.com/blog/1850238
博文转发，方便学习。如有不当之处，请告知作者
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
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
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:
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
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
对于基本路由, rails2:
map.connect 'login', :controller => 'session', :action => 'new'
那么在rails3中:
match 'login' => 'session#new'
对于具名路由, rails2:
map.login 'login', :controller => 'session', :action => 'new'
在rails3中:
match 'login' => 'session#new', :as => :login
对于程序根路由, rails2:
map.root :controller => 'users', :action => 'index'
rails3:
root :to => 'users#index'
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)))'
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"
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"
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"
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/')
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
对于Rack应用, rails3:
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:
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
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:
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:
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:
def welcome(user, subdomain)
subject 'Welcome to TestApp'
recipients user.email
from '[email protected]'
body :user => user, :subdomain => subdomain
end
UserMailer.deliver_welcome(user, subdomain)
在rails3中:
def welcome(user, subdomain)
@user = user
@subdomain = subdomain
mail(:from => "[email protected]",
:to => user.email,
:subject => "Welcome to TestApp")
end
UserMailer.welcome(user, subdomain).deliver
相比rails2, 我们在rails3下实现一个mail要简单的多:
class UserMailer < ActionMailer::Base
default :from => "[email protected]",
:reply_to => "[email protected]",
"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:
@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:
@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
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
对于查找方法, rails2:
Post.find(:all, :conditions => {:author => "Joe"}, :includes => :comments, :order => "title", :limit => 10)
在rails3:
Post.find(:all, :conditions => {:author => "Joe"}, :includes => :comments,
:order => "title", :limit => 10)
在rails 2中关联2个表时如下用：
User.find( :all, :joins => :profile, :conditions => ['profile.age = ?', 33])
在rails 3中变成如下
User.joins(:profile).where('profile.age = ?', 33)
区别在于，后者可以跟each，all，count， first
query = User.joins(:profile).where('profile.age = ?', 33)
query.where('users.name = ?', name) unless name.nil?
query.where('profile.email = ?', email) unless email.nil?
query.all
因为有了AREL的支持
https://github.com/rails/arel
最大的优势是组合和lazy loading
class User
scope :by_age, lambda do |age|
joins(:profile).where('profile.age = ?', age) unless age.nil?
end
scope :by_name, lambda{ |name| where(name: name) unless name.nil? }
scope :by_email, lambda do |email|
joins(:profile).where('profile.email = ?', email) unless email.nil?
end
end
User.by_age(33).by_name(params[:name]).by_email(params[:email]).all
当然还有重用
class Tag
belongs_to :post
end
class Post
has_many :tags
belongs_to :user
scope :tagged, lambda do |tag|
joins(:tags).where('tags.name = ?', tag).group('posts.id')
end
end
class User
has_many :posts
end
# 标记为 'ruby-on-rails'，并且是特定user的帖子
User.where('users.id = ?', 232423).posts.tagged('ruby-on-rails').count
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