Code Refactoring Javaeye Rails1.X 2.X

从 rails 1.x 到 2.x

重构你的应用

Agenda 重构前后的变化

开发模式的改变

Database Migration RESTful Resource

重构实例数据校验

acts_as_xxx Fat Model / Rich Domain Object 避免 monkey patch javascript / css 优化

Q & A

重构前后的变化

++++++++| Name | Lines | LOC | Classes | Methods | M/C | LOC/M |++++++++| Controllers | 3006 | 2556 | 49 | 407 | 8 | 4 || Helpers | 537 | 492 | 0 | 47 | 0 | 8 || Models | 2169 | 1805 | 54 | 262 | 4 | 4 || Libraries | 932 | 753 | 8 | 80 | 10 | 7 || Model specs | 1270 | 974 | 0 | 0 | 0 | 0 || View specs | 0 | 0 | 0 | 0 | 0 | 0 || Controller specs | 181 | 101 | 0 | 0 | 0 | 0 || Helper specs | 111 | 91 | 0 | 0 | 0 | 0 |++++++++| Total | 8206 | 6772 | 111 | 796 | 7 | 6 |++++++++ Code LOC: 5606 Test LOC: 1166 Code to Test Ratio: 1:0.2

++++++++| Name | Lines | LOC | Classes | Methods | M/C | LOC/M |++++++++| Controllers | 4508 | 3868 | 17 | 373 | 21 | 8 || Helpers | 1311 | 1112 | 0 | 86 | 0 | 10 || Models | 3153 | 2121 | 45 | 205 | 4 | 8 || Libraries | 1379 | 885 | 7 | 80 | 11 | 9 |++++++++| Total | 10351 | 7986 | 69 | 744 | 10 | 8 |++++++++ Code LOC: 7986 Test LOC: 0 Code to Test Ratio: 1:0.0

200712

200807

重构前后的变化

代码行数 7986 => 5606

每个方法的平均代码行数 8 => 4

测试代码 0 => 1166

功能比原先更多增加了知识库，问答频道，博客频道，垂直频道完善了个人博客，新闻频道，全文检索，后台管理

这些改变是如何发生的？从 Rails1.x ~ 2.x 的新特性驱动

从开源软件中不断学习 Rails 开发最佳实践

什么是重构

http://en.wikipedia.org/wiki/Refactoring

在保持功能一致的前提下，让代码变得更容易阅读减少重复的代码减少代码复杂度更适应将来的扩展

Database Migrations

0.x 手工维护

1.x database migration script

2.x sexy migration

DRY – Don't Repeat Yourself

class CreateUsers < ActiveRecord::Migration def self.up create_table :users do |t| t.column :name, :string, :null => false

class CreateCompanies < ActiveRecord::Migration def self.up create_table :companies do |t| t.string :name, :null => false

RESTful Resource

1.x routes.rb

2.x routes.rb

COC Convention over Configuration

map.connect 'members', :controller => 'group', :action => 'members' map.connect ':controller/:action/:id' map.connect ':controller/:action'

map.resource :group_setting, :controller => 'group/admin/group_setting'

map.resources :group_users, :controller => 'group/admin/group_users',

:member => {:approve => :put}, :collection => {:search => :get}

重构实例一数据校验

Before

After

def create #... if @news.save redirect_to :action => :show, :id => @news.id else render :action => 'new' end end

def create #... @news.save! redirect_to news_path(@news) end

重构实例一数据校验

application.rb

学自 Beast http://beast.caboo.se/

def rescue_action(exception) exception.is_a?(ActiveRecord::RecordInvalid) ? render_invalid_record(exception.record) end

def render_invalid_record(record) @invalid_record = record respond_to do |format| format.html do render :action => (record.new_record? ? 'new' : 'edit') end format.js do render :update do |page| page.alert @invalid_record.errors.full_messages.join("\n") end end end end

http://beast.caboo.se/

http://beast.caboo.se/

重构实例二 acts_as_xxx

Before

After

class Topic < ActiveRecord::Base serialize :rate_data def rateable_by?(user) #... end

def new_rate(user, type) #... endend

module RateableModel def self.included(model) model.serialize :rate_data end

def rateable_by?(user) #... endend

class Post < ActiveRecord::Base serialize :rate_data def rateable_by?(user) #... end

def new_rate(user, type) #... endend

class Topic < ActiveRecord::Base include RateableModel

class Post < ActiveRecord::Base include RateableModel

重构实例二 act_as_xxx

持续改进，更加符合 Rails 的 DSL 习惯： acts_as_xxx

学自 Rails 自带功能，如 acts_as_list

从 Plugin 中学习，如 acts_as_cached, acts_as_taggable

class Topic < ActiveRecord::Base acts_as_rateable

class Post < ActiveRecord::Base acts_as_rateable

重构实例三 Fat Model / Rich Domain Object

显示圈子共享文件 groups_controller.rb

Controller 放置了太多的逻辑

不符合 MVC 的理念

单元测试困难代码重用度低

利用 Rails 提供的各种特性，将代码转移到 Model 上

def share @latest_attachments = Attachment.find(:all, :conditions => ["group_id = ?", @group.id], :limit => 5) @total_size = Attachment.sum(:size, :conditions => ["group_id = ?", @group.id])end


group.rb

groups_controller.rb

学自 <Agile Web Development with Rails> 和 Rails doc

has_many :attachments, :order => 'id DESC' do def latest(number = 5) find(:all, :limit => number) end

def total_size sum(:size) || 0 end end

def share @latest_attachments = @group.attachments.latest @total_size = @group.attachments.total_sizeend


named_scope

学自 Rails 2.1 新特性

ActiveRecord 的动态特性让实现 Rich Domain Object 变的轻松

associations' dynamic operation named_scope, with_scope dirty_check method_missing (e.g will_paginate)

class News < ActiveRecord::Base named_scope :categoried_by, lambda { |category| { :conditions => ['category = ?', category] } named_scope :recent, lambda { |days| { :conditions => ['created_at >= ?', days.ago] }end

News.categoried_by("ruby")News.recent(3.days).categoried_by("ruby")

重构实例四避免 monkey patch

什么是 monkey patch?http://en.wikipedia.org/wiki/Monkey_patch

方便，简单但是不利于 Rails/Plugin 升级

实例：压缩用户头像

module MiniMagick class Image def compressing(convert_gif) format = self[:format] if convert_gif && format == "GIF" #convert 1st frame for animation gif run_command("convert","#{@path}[0]", "#{@path}") elsif format == "BMP" format("PNG") end end endend

重构实例四避免 monkey patch

monkey patch

initializers/attachment_fu.rb

#直接修改 mini_magick_processor.rb的 resize_image方法def resize_image(img, size) img.compressing(true) #...end

#利于 Rails提供的 alias_method_chain做修改Technoweenie::AttachmentFu::Processors::MiniMagickProcessor.module_eval do def resize_image_with_compressing(img, size) img.compressing(true) resize_image_without_compressing(img, size) end

alias_method_chain :resize_image, :compressingend

重构实例五 javascript/css 优化

Yslow http://developer.yahoo.com/yslow/

避免使用 javascript_include_tag :defaults

ActionController::Base.asset_host = "http://www.javaeye.com"

合并常用 javascript 文件，对首页做特别优化

减少 CSS 请求

开发时使用多个 CSS 文件

发布时候用脚本合并

http://developer.yahoo.com/yslow/

http://www.javaeye.com/

重构实例五 javascript/css 优化

DIR_PATH = "public/stylesheets"IMPORT_EXP = /@import url$ (.*) $;/COMMENT_EXP = /^\/\*(.*)\*\/$/

def pack(file_name) file_path = File.expand_path(file_name) dir_name = File.dirname(file_path) f = File.new(file_path, "r") result = "" while (line = f.gets) if m = IMPORT_EXP.match(line) result << pack("#{dir_name}/#{m[1]}") else result << line unless line =~ COMMENT_EXP end end resultend

Dir.foreach(DIR_PATH) { |f| if f =~ /.css$/ file_name = "#{DIR_PATH}/#{f}" result = pack(file_name) File.open(file_name, "w") do |file| file.puts result end end}

@import url( themes/basic/tools.css );@import url( themes/basic/typo.css );@import url( themes/basic/forms.css );@import url( themes/basic/layout.css );@import url( themes/javaeye2.css );@import url( themes/news_default.css );

开发时多个 CSS

发布时候使用合并脚本 =>

Code Refactoring Javaeye Rails1.X 2.X

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