jay16/rails router: 路由过滤

## rails router: 路由过滤
有时由于一些原因需要限制url链接中传过来的参数符合我们定制的规则，对参数的限制在路由配置时使用**constraints**关键定。

例如限制参数id的值以A开头，应该这样写：

~~~~ ruby
get 'photos/:id', to: 'photos#show', constraints: { id: /[A-Z]\d{5}/ }

#等同于

get 'photos/:id', to: 'photos#show', id: /[A-Z]\d{5}/

#/photos/A12345 => 可以正常访问
#/photos/893    => 会被路由过滤掉，而访问失败
~~~~

## 基础用法

上面的用法也属于基础用法，使用constraints还可以限制约束url的结构，例如管理文章的url中约束为admin/*，可以这样写:

~~~~ ruby
get 'photos', constraints: {subdomain: 'admin'}

#等同于

namespace :admin do
  constraints subdomain: 'admin' do
    resources :photos
  end
end
~~~~

## 高级用法

可以像rails实现router约束的原理一样，提供一个含`matches?`方法的对象来使用constraints的高级用法。

举个实例来说明constraints的高级用法,假如我们有一个用户ip列表，只有这个列表中的ip才可以访问我们指定的网页。

先介绍它的简洁用法，是直接在constraints里调用`lambda`。

~~~~ ruby
TwitterClone::Application.routes.draw do
  get '*path', to: 'blacklist#index',
    constraints: lambda { |request| Blacklist.retrieve_ips.include?(request.remote_ip) }
end
~~~~

如果约束的条件比较多，都写在router里会显示臃肿，这时可以写一个module文件专门来写定义约束，这个文件放在`config/initializers`路径下，rails启动时会自动加载这个module,可以在router里直接调用。

~~~~ ruby
#config/initializers/self_router.rb
class SelfRouter
  def initialize
    @ips = Blacklist.retrieve_ips
  end

  def matches?(request)
    @ips.include?(request.remote_ip)
  end
end

#config/router
get '*path', to: 'blacklist#index',
  constraints: SelfRouter.new
~~~~


## 微信实例

微信消息的接收就符合使用constraints。先说明一下微信消息接收的规则，它只对一个url(假设为http://xsolife.com/weixin)发送验证、文本、语音、位置等微信消息，不同微信消息的区分是微信服务器在触发url时传过的参数**type**.

无论是在控制器的方法中，还是在router中针对type来作判断，都会让代码非丑陋，而需求有改变时调整代码也是很痛苦的，constraints可以优美的化解这个窘迫处境。

~~~~ ruby
#config/initializers/weixin_router.rb
#encoding : utf-8
module Weixin
  # 微信内部路由规则类，用于简化配置
  class Router

    # 支持以下形式
    def initialize(options, &block)
      @type       = options[:type]    if options[:type]
      @content    = options[:content] if options[:content]
      @constraint = block if block_given?
    end

    def matches?(request)
      xml = request.params[:xml]
      result = true
      result = result && (xml[:MsgType] == @type) if @type
      result = result && (xml[:Content] =~ @content) if @content.is_a? Regexp
      result = result && (xml[:Content] == @content) if @content.is_a? String
      result = result && @constraint.call(xml) if @constraint

      return result
    end
  end

  module ActionController
    # 辅助方法，用于简化操作，weixin_xml.content 比用hash舒服
    def weixin_xml
      @weixin_xml ||= WeixinXml.new(params[:xml])
      return @weixin_xml
    end

    class WeixinXml
      #对微信所有消息类型都做了定义
      attr_accessor :to_user_name, :from_user_name, :create_time, :msg_type, :msg_id
      attr_accessor :content                                 #text
      attr_accessor :pic_url, :media_id                      #image
      attr_accessor :media_id, :format                       #voice
      attr_accessor :media_id, :thumb_media_id               #video
      attr_accessor :location_x, :location_y, :scale, :label #location
      attr_accessor :title, :description, :url               #link
      attr_accessor :event, :event_key, :ticket              #event, scan
      attr_accessor :event, :latitude, :longitude, :precision

      def initialize(hash)
        @to_user_name = hash[:ToUserName]
        @from_user_name = hash[:FromUserName]
        @create_time = hash[:CreateTime]
        @msg_type = hash[:MsgType]
        @msg_id = hash[:MsgId]
        @content = hash[:Content]
        @pic_url = hash[:PicUrl]
        @media_id = hash[:MediaId]
        @format = hash[:Format]
        @thumb_media_id = hash[:ThumbMediaId]
        @location_x = hash[:Location_X]
        @location_y = hash[:Location_Y]
        @scale = hash[:Scale]
        @label = hash[:Label]
        @title = hash[:Title]
        @description = hash[:Description]
        @url = hash[:Url]
        @event = hash[:Event]
        @event_key = hash[:EventKey]
        @ticket = hash[:Ticket]
        @latitude = hash[:Latitude]
        @longitude = hash[:Longitude]
        @precision = hash[:Precision]
      end
    end
  end
end

#让方法weixin可以直接在ActionController、ActionView被直接调用
ActionController::Base.class_eval do
  include ::Weixin::ActionController
end
ActionView::Base.class_eval do
  include ::Weixin::ActionController
end

####################################################
####################################################

#config/router
#处理weixin消息
scope :path => "/weixin", :via => :post, :defaults => {:format => "xml"} do
    #接收事件推送
    root :to => "weixin#event", :constraints => Weixin::Router.new(:type => "event")
    #接收普通消息
    root :to => "weixin#receive", :constraints => Weixin::Router.new(:type => "text")
    root :to => "weixin#receive", :constraints => Weixin::Router.new(:type => "image")
    root :to => "weixin#receive", :constraints => Weixin::Router.new(:type => "voice")
    root :to => "weixin#receive", :constraints => Weixin::Router.new(:type => "video")
    root :to => "weixin#receive", :constraints => Weixin::Router.new(:type => "location")
    root :to => "weixin#receive", :constraints => Weixin::Router.new(:type => "link")
    root :to => "weixin#other" #没有被处理到的事件
end
match "/weixin" => "weixin#authen", :via => :get

####################################################
####################################################

class WeixinController < ApplicationController
  skip_before_filter :verify_authenticity_token
  before_filter :receve_xml,   except: [:authen]
  respond_to :xml, :html, :js

  def event; end
  def receive; end
  def other; end

  #weixin开发模式验证
  def authen
    if params[:nonce] #weixin服务器验证url
      array = [Rails.configuration.weixin_token, params[:timestamp], params[:nonce]].sort
      if params[:signature] == Digest::SHA1.hexdigest(array.join)
        render :text => params[:echostr]
      else
        render :text => "Forbidden", :status => 403
      end
    else              #个人访问
      render :template => "weixin/index"
    end
  end

  def receve_xml
    @weixin = weixin_xml
  end
end

####################################################
####################################################

#app/view/weixin/receive.xml.erb
<xml>
<ToUserName><![CDATA[<%= @weixin.from_user_name %>]]></ToUserName>
<FromUserName><![CDATA[<%= @weixin.to_user_name %>]]></FromUserName>
<CreateTime><%= Time.now.to_i %></CreateTime>
<MsgType><![CDATA[news]]></MsgType>
<Content><![CDATA[]]></Content>
<ArticleCount>3</ArticleCount>
<Articles>
  <item>
    <Title><![CDATA[MailHok 邮件确达服务]]></Title>
    <Description><![CDATA[IntFocus 企业级群发邮件服务]]></Description>
    <PicUrl><![CDATA[http://xsolife.com/photos/f6326272-2513-304e-83a8-c39f5063ca71/bd4d432b-6cab-389a-a0fe-e20d7b7e7fb5.png]]></PicUrl>
    <Url><![CDATA[http://main.intfocus.com]]></Url>
  </item>
  <item>
    <Title><![CDATA[SOLife 微信]]></Title>
    <Description><![CDATA[SOLife微主测试明细]]></Description>
    <PicUrl><![CDATA[http://xsolife.com/photos/f6326272-2513-304e-83a8-c39f5063ca71/a09c60fb-f73e-300a-9fce-49e4c0d0165e.jpg]]></PicUrl>
    <Url><![CDATA[http://xsolife.com/weixin]]></Url>
  </item>
  <item>
    <Title><![CDATA[<%= "您的[#{@weixin.msg_type}]消息详情" %>]]></Title>
    <Description><![CDATA[<%= "您的[#{@weixin.msg_type}]消息已收到.\n查看详情清点击: http://xsolife.com/weixin/#{@record.id}" %>]]></Description>
    <PicUrl><![CDATA[http://xsolife.com/photos/f6326272-2513-304e-83a8-c39f5063ca71/a09c60fb-f73e-300a-9fce-49e4c0d0165e.jpg]]></PicUrl>
    <Url><![CDATA[<%= "http://xsolife.com/weixin/#{@record.id}" %>]]></Url>
  </item>
<Articles>
</xml>

####################################################

#app/view/weixin/event.xml.erb
<xml>
<ToUserName><![CDATA[<%= @weixin.from_user_name %>]]></ToUserName>
<FromUserName><![CDATA[<%= @weixin.to_user_name %>]]></FromUserName>
<CreateTime><%= Time.now.to_i %></CreateTime>
<MsgType><![CDATA[text]]></MsgType>
<Content><![CDATA[<%= @weixin.event == "subscribe" ? "欢迎关注SOLife微信./::~" : "谢谢您的使用./::~" %>]]></Content>
</xml>

####################################################

#app/view/weixin/other.xml.erb
<xml>
<ToUserName><![CDATA[<%= @weixin.from_user_name %>]]></ToUserName>
<FromUserName><![CDATA[<%= @weixin.to_user_name %>]]></FromUserName>
<CreateTime><%= Time.now.to_i %></CreateTime>
<MsgType><![CDATA[text]]></MsgType>
<Content><![CDATA[<%= "hi,\n已收到您的信息[但未能正确判断消息类型]" %>]]></Content>
</xml>
~~~
	有时由于一些原因需要限制url链接中传过来的参数符合我们定制的规则，对参数的限制在路由配置时使用constraints关键定。

	例如限制参数id的值以A开头，应该这样写：

	~~~~ ruby
	get 'photos/:id', to: 'photos#show', constraints: { id: /[A-Z]\d{5}/ }

	#等同于

	get 'photos/:id', to: 'photos#show', id: /[A-Z]\d{5}/

	#/photos/A12345 => 可以正常访问
	#/photos/893 => 会被路由过滤掉，而访问失败
	~~~~

	## 基础用法

	上面的用法也属于基础用法，使用constraints还可以限制约束url的结构，例如管理文章的url中约束为admin/*，可以这样写:

	~~~~ ruby
	get 'photos', constraints: {subdomain: 'admin'}

	#等同于

	namespace :admin do
	constraints subdomain: 'admin' do
	resources :photos
	end
	end
	~~~~

	## 高级用法

	可以像rails实现router约束的原理一样，提供一个含`matches?`方法的对象来使用constraints的高级用法。

	举个实例来说明constraints的高级用法,假如我们有一个用户ip列表，只有这个列表中的ip才可以访问我们指定的网页。

	先介绍它的简洁用法，是直接在constraints里调用`lambda`。

	~~~~ ruby
	TwitterClone::Application.routes.draw do
	get '*path', to: 'blacklist#index',
	constraints: lambda { \|request\| Blacklist.retrieve_ips.include?(request.remote_ip) }
	end
	~~~~

	如果约束的条件比较多，都写在router里会显示臃肿，这时可以写一个module文件专门来写定义约束，这个文件放在`config/initializers`路径下，rails启动时会自动加载这个module,可以在router里直接调用。

	~~~~ ruby
	#config/initializers/self_router.rb
	class SelfRouter
	def initialize
	@ips = Blacklist.retrieve_ips
	end

	def matches?(request)
	@ips.include?(request.remote_ip)
	end
	end

	#config/router
	get '*path', to: 'blacklist#index',
	constraints: SelfRouter.new
	~~~~


	## 微信实例

	微信消息的接收就符合使用constraints。先说明一下微信消息接收的规则，它只对一个url(假设为http://xsolife.com/weixin)发送验证、文本、语音、位置等微信消息，不同微信消息的区分是微信服务器在触发url时传过的参数type.

	无论是在控制器的方法中，还是在router中针对type来作判断，都会让代码非丑陋，而需求有改变时调整代码也是很痛苦的，constraints可以优美的化解这个窘迫处境。

	~~~~ ruby
	#config/initializers/weixin_router.rb
	#encoding : utf-8
	module Weixin
	# 微信内部路由规则类，用于简化配置
	class Router

	# 支持以下形式
	def initialize(options, &block)
	@type = options[:type] if options[:type]
	@content = options[:content] if options[:content]
	@constraint = block if block_given?
	end

	def matches?(request)
	xml = request.params[:xml]
	result = true
	result = result && (xml[:MsgType] == @type) if @type
	result = result && (xml[:Content] =~ @content) if @content.is_a? Regexp
	result = result && (xml[:Content] == @content) if @content.is_a? String
	result = result && @constraint.call(xml) if @constraint

	return result
	end
	end

	module ActionController
	# 辅助方法，用于简化操作，weixin_xml.content 比用hash舒服
	def weixin_xml
	@weixin_xml \|\|= WeixinXml.new(params[:xml])
	return @weixin_xml
	end

	class WeixinXml
	#对微信所有消息类型都做了定义
	attr_accessor :to_user_name, :from_user_name, :create_time, :msg_type, :msg_id
	attr_accessor :content #text
	attr_accessor :pic_url, :media_id #image
	attr_accessor :media_id, :format #voice
	attr_accessor :media_id, :thumb_media_id #video
	attr_accessor :location_x, :location_y, :scale, :label #location
	attr_accessor :title, :description, :url #link
	attr_accessor :event, :event_key, :ticket #event, scan
	attr_accessor :event, :latitude, :longitude, :precision

	def initialize(hash)
	@to_user_name = hash[:ToUserName]
	@from_user_name = hash[:FromUserName]
	@create_time = hash[:CreateTime]
	@msg_type = hash[:MsgType]
	@msg_id = hash[:MsgId]
	@content = hash[:Content]
	@pic_url = hash[:PicUrl]
	@media_id = hash[:MediaId]
	@format = hash[:Format]
	@thumb_media_id = hash[:ThumbMediaId]
	@location_x = hash[:Location_X]
	@location_y = hash[:Location_Y]
	@scale = hash[:Scale]
	@label = hash[:Label]
	@title = hash[:Title]
	@description = hash[:Description]
	@url = hash[:Url]
	@event = hash[:Event]
	@event_key = hash[:EventKey]
	@ticket = hash[:Ticket]
	@latitude = hash[:Latitude]
	@longitude = hash[:Longitude]
	@precision = hash[:Precision]
	end
	end
	end
	end

	#让方法weixin可以直接在ActionController、ActionView被直接调用
	ActionController::Base.class_eval do
	include ::Weixin::ActionController
	end
	ActionView::Base.class_eval do
	include ::Weixin::ActionController
	end

	####################################################
	####################################################

	#config/router
	#处理weixin消息
	scope :path => "/weixin", :via => :post, :defaults => {:format => "xml"} do
	#接收事件推送
	root :to => "weixin#event", :constraints => Weixin::Router.new(:type => "event")
	#接收普通消息
	root :to => "weixin#receive", :constraints => Weixin::Router.new(:type => "text")
	root :to => "weixin#receive", :constraints => Weixin::Router.new(:type => "image")
	root :to => "weixin#receive", :constraints => Weixin::Router.new(:type => "voice")
	root :to => "weixin#receive", :constraints => Weixin::Router.new(:type => "video")
	root :to => "weixin#receive", :constraints => Weixin::Router.new(:type => "location")
	root :to => "weixin#receive", :constraints => Weixin::Router.new(:type => "link")
	root :to => "weixin#other" #没有被处理到的事件
	end
	match "/weixin" => "weixin#authen", :via => :get

	####################################################
	####################################################

	class WeixinController < ApplicationController
	skip_before_filter :verify_authenticity_token
	before_filter :receve_xml, except: [:authen]
	respond_to :xml, :html, :js

	def event; end
	def receive; end
	def other; end

	#weixin开发模式验证
	def authen
	if params[:nonce] #weixin服务器验证url
	array = [Rails.configuration.weixin_token, params[:timestamp], params[:nonce]].sort
	if params[:signature] == Digest::SHA1.hexdigest(array.join)
	render :text => params[:echostr]
	else
	render :text => "Forbidden", :status => 403
	end
	else #个人访问
	render :template => "weixin/index"
	end
	end

	def receve_xml
	@weixin = weixin_xml
	end
	end

	####################################################
	####################################################

	#app/view/weixin/receive.xml.erb
	<xml>
	<ToUserName><![CDATA[<%= @weixin.from_user_name %>]]></ToUserName>
	<FromUserName><![CDATA[<%= @weixin.to_user_name %>]]></FromUserName>
	<CreateTime><%= Time.now.to_i %></CreateTime>
	<MsgType><![CDATA[news]]></MsgType>
	<Content><![CDATA[]]></Content>
	<ArticleCount>3</ArticleCount>
	<Articles>
	<item>
	<Title><![CDATA[MailHok 邮件确达服务]]></Title>
	<Description><![CDATA[IntFocus 企业级群发邮件服务]]></Description>
	<PicUrl><![CDATA[http://xsolife.com/photos/f6326272-2513-304e-83a8-c39f5063ca71/bd4d432b-6cab-389a-a0fe-e20d7b7e7fb5.png]]></PicUrl>
	<Url><![CDATA[http://main.intfocus.com]]></Url>
	</item>
	<item>
	<Title><![CDATA[SOLife 微信]]></Title>
	<Description><![CDATA[SOLife微主测试明细]]></Description>
	<PicUrl><![CDATA[http://xsolife.com/photos/f6326272-2513-304e-83a8-c39f5063ca71/a09c60fb-f73e-300a-9fce-49e4c0d0165e.jpg]]></PicUrl>
	<Url><![CDATA[http://xsolife.com/weixin]]></Url>
	</item>
	<item>
	<Title><![CDATA[<%= "您的[#{@weixin.msg_type}]消息详情" %>]]></Title>
	<Description><![CDATA[<%= "您的[#{@weixin.msg_type}]消息已收到.\n查看详情清点击: http://xsolife.com/weixin/#{@record.id}" %>]]></Description>
	<PicUrl><![CDATA[http://xsolife.com/photos/f6326272-2513-304e-83a8-c39f5063ca71/a09c60fb-f73e-300a-9fce-49e4c0d0165e.jpg]]></PicUrl>
	<Url><![CDATA[<%= "http://xsolife.com/weixin/#{@record.id}" %>]]></Url>
	</item>
	<Articles>
	</xml>

	####################################################

	#app/view/weixin/event.xml.erb
	<xml>
	<ToUserName><![CDATA[<%= @weixin.from_user_name %>]]></ToUserName>
	<FromUserName><![CDATA[<%= @weixin.to_user_name %>]]></FromUserName>
	<CreateTime><%= Time.now.to_i %></CreateTime>
	<MsgType><![CDATA[text]]></MsgType>
	<Content><![CDATA[<%= @weixin.event == "subscribe" ? "欢迎关注SOLife微信./::~" : "谢谢您的使用./::~" %>]]></Content>
	</xml>

	####################################################

	#app/view/weixin/other.xml.erb
	<xml>
	<ToUserName><![CDATA[<%= @weixin.from_user_name %>]]></ToUserName>
	<FromUserName><![CDATA[<%= @weixin.to_user_name %>]]></FromUserName>
	<CreateTime><%= Time.now.to_i %></CreateTime>
	<MsgType><![CDATA[text]]></MsgType>
	<Content><![CDATA[<%= "hi,\n已收到您的信息[但未能正确判断消息类型]" %>]]></Content>
	</xml>
	~~~