Ruby on Rails tutorial 3rd 中文版

Ruby on Rails Rails Web

Michael Hartl

. 3

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3 ............................................................................................................................... 633.1.d 633.2. 653.3. 733.4.pT 783.5. 873.6. 883.7. 90

4 Rails Ruby ........................................................................................................................... 974.1. 974.2. 100

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5 ........................................................................................................................................ 1255.1.n" 1255.2. Sass Asset Pipeline 1405.3. 1485.4.U 1545.5. 1575.6. 158

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- vii

Ruby T@*David Heinemeier Hansson 1 Rails 1 RubyRails d Ruby on Rails Web E&,E&Ruby on Rails Tutorial."Cg Rails Web

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Michael HartlRuby on Rails Tutoriald

Ruby is a delightful computer language explicitly designed to make programmers happy. This philosophy influencedDavid Heinemeier Hansson to pick Ruby when implementing the Rails web framework. Ruby on Rails, as its oftencalled, makes building custom web applications faster and easier than ever before. In the past few years, the Ruby onRails Tutorial has become the leading introduction to web development with Rails.

In our interconnected world, computer programming and web application development are rapidly rising in impor-tance, and I am excited to support Ruby on Rails in China. Although it is important to learn English, which is the in-ternational language of programming, its often helpful at first to learn in your native language. It is for this reasonthat I am grateful to Andor Chen for producing the Chinese-language edition of the Ruby on Rails Tutorial book.

Ive never been to China, but I definitely plan to visit some day. I hope Ill have the chance to meet some of you whenI do!

Best wishes and good luck,

Michael HartlAuthor

The Ruby on Rails Tutorial

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.dMichael Hartl Ruby on Rails Web C@(,SoftCover@H(d1 RailsSpace Rails ,g Ruby onRails " Insoshi

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.Ruby on Rails Tutorial: Learn Web Development with Rails (Third Edition).`dMichael Hartl Michael Hartl

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.I6MIT Beerware

The MIT License

Copyright (c) 2014 Michael Hartl

Permission is hereby granted, free of charge, to any person obtaining a copy

of this software and associated documentation files (the "Software"), to deal

in the Software without restriction, including without limitation the rights

to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

copies of the Software, and to permit persons to whom the Software is

furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in

all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN

THE SOFTWARE.

/*

* ----------------------------------------------------------------------------

* "THE BEERWARE LICENSE" (Revision 43):

* Michael Hartl wrote this code. As long as you retain this notice you

* can do whatever you want with this stuff. If we meet some day, and you think

* this stuff is worth it, you can buy me a beer in return.

* ----------------------------------------------------------------------------

*/

xvii

1 +

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class User < ActiveRecord::Base

validates :name, presence: true

validates :email, presence: true

end

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has_secure_password

end

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ls $ ls -l

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$ cd ..

$cd ~ $ cd

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M cp $ cp README.rdoc README.md

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create

create README.rdoc

create Rakefile

create config.ru

create .gitignore

create Gemfile

create app

create app/assets/javascripts/application.js

create app/assets/stylesheets/application.css

create app/controllers/application_controller.rb

.

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create test/test_helper.rb

create tmp/cache

create tmp/cache/assets

create vendor/assets/javascripts

create vendor/assets/javascripts/.keep

create vendor/assets/stylesheets

create vendor/assets/stylesheets/.keep

run bundle install

Fetching gem metadata from https://rubygems.org/..........

Fetching additional metadata from https://rubygems.org/..

Resolving dependencies...

Using rake 10.3.2

Using i18n 0.6.11

.

.

.

Your bundle is complete!

Use `bundle show [gemname]` to see where a bundled gem is installed.

run bundle exec spring binstub --all

* bin/rake: spring inserted

* bin/rails: spring inserted

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source 'https://rubygems.org'

# Bundle edge Rails instead: gem 'rails', github: 'rails/rails'

gem 'rails', '4.2.0'

# Use sqlite3 as the database for Active Record

gem 'sqlite3'

# Use SCSS for stylesheets

gem 'sass-rails', '~> 5.0.0.beta1'

# Use Uglifier as compressor for JavaScript assets

gem 'uglifier', '>= 1.3.0'

# Use CoffeeScript for .js.coffee assets and views

gem 'coffee-rails', '~> 4.0.0'

# See https://github.com/sstephenson/execjs#readme for more supported runtimes

# gem 'therubyracer', platforms: :ruby

# Use jquery as the JavaScript library

gem 'jquery-rails'

# Turbolinks makes following links in your web application faster. Read more:

# https://github.com/rails/turbolinks

gem 'turbolinks'

# Build JSON APIs with ease. Read more: https://github.com/rails/jbuilder

gem 'jbuilder', '~> 2.0'

# bundle exec rake doc:rails generates the API under doc/api.

gem 'sdoc', '~> 0.4.0', group: :doc

1.3. - 11

# Use ActiveModel has_secure_password

# gem 'bcrypt', '~> 3.1.7'

# Use Unicorn as the app server

# gem 'unicorn'

# Use Capistrano for deployment

# gem 'capistrano-rails', group: :development

group :development, :test do

# Call 'debugger' anywhere in the code to stop execution and get a

# debugger console

gem 'byebug'

# Access an IRB console on exceptions page and /console in development

gem 'web-console', '~> 2.0.0.beta2'

# Spring speeds up development by keeping your application running in the

# background. Read more: https://github.com/rails/spring

gem 'spring'

end

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gem 'sqlite3'

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gem 'uglifier', '>= 1.3.0'

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gem 'coffee-rails', '~> 4.0.0'

12 - 1 +

1.5 Gemfile

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gem 'sass-rails', '5.0.0.beta1'

gem 'uglifier', '2.5.3'

gem 'coffee-rails', '4.1.0'

gem 'jquery-rails', '4.0.0.beta2'

gem 'turbolinks', '2.3.0'

gem 'jbuilder', '2.2.3'

gem 'sdoc', '0.4.0', group: :doc


1.3. - 13

gem 'sqlite3', '1.3.9'

gem 'byebug', '3.4.0'

gem 'web-console', '2.0.0.beta3'

gem 'spring', '1.1.3'

end

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Fetching source index for https://rubygems.org/

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=> Ctrl-C to shutdown server

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=> Rails application starting on http://0.0.0.0:8080

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=> Ctrl-C to shutdown server

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class ApplicationController < ActionController::Base

# Prevent CSRF attacks by raising an exception.

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protect_from_forgery with: :exception

def hello

render text: "hello, world!"

end

end

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root 'application#hello'

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# Ruby on Rails Tutorial: "hello, world!"

This is the first application for the

[*Ruby on Rails Tutorial*](http://www.railstutorial.org/)

by [Michael Hartl](http://www.michaelhartl.com/).

#

$ git status

On branch modify-README

Changes to be committed:

(use "git reset HEAD ..." to unstage)

renamed: README.rdoc -> README.md

Changes not staged for commit:

(use "git add ..." to update what will be committed)

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modified: README.md

LKg 1.4.1.2 git add -A\ git commiti1 -aK Git Gi - 27

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gem 'rails_12factor', '0.0.2'

end

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gem 'pg', '0.17.1'


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http://damp-fortress-5769.herokuapp.com/ | [email protected]:damp-fortress-5769.git

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gem 'pg', '0.17.1'


end

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scaffoldW rails generateKg Rails 1W scaffold User3K;

$ rails generate scaffold User name:string email:string

invoke active_record

create db/migrate/20140821011110_create_users.rb

create app/models/user.rb

invoke test_unit

create test/models/user_test.rb

create test/fixtures/users.yml

invoke resource_route

route resources :users

invoke scaffold_controller

create app/controllers/users_controller.rb

invoke erb

create app/views/users

create app/views/users/index.html.erb

create app/views/users/edit.html.erb

create app/views/users/show.html.erb

create app/views/users/new.html.erb

create app/views/users/_form.html.erb

invoke test_unit

create test/controllers/users_controller_test.rb

invoke helper

create app/helpers/users_helper.rb

invoke test_unit

create test/helpers/users_helper_test.rb

invoke jbuilder

create app/views/users/index.json.jbuilder

create app/views/users/show.json.jbuilder

invoke assets

invoke coffee

create app/assets/javascripts/users.js.coffee

invoke scss

create app/assets/stylesheets/users.css.scss

invoke scss

create app/assets/stylesheets/scaffolds.css.scss

3. ggg User Users

38 - 2 S

LJ1 name:string email:stringK 2.21 idRails V"#primary key

L Rake 2.1migrate

$ bundle exec rake db:migrate

== CreateUsers: migrating ==============================================

-- create_table(:users)

-> 0.0017s

== CreateUsers: migrated (0.0018s) =====================================

JVg'6.1.1 VC"1gGemfile Rake L bundle exec rake7 IDEg bundle exec\;gK"1JVg bundle exec

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Unix Linux Mac OS XJI

Rake Ruby make Ruby make Rails 1 Rake i16 Web Orake db:migrate(HJ rake -T dbKO

$ bundle exec rake -T db

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4. railsg bundle exec

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2.5http://localhost:30007 IDE V 7 V

LKMCreate UserV 2.6flash message7.4.2 VC URL /users/1e1 1 2.2 id7.1 V

40 - 2 S

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2. Rails /users

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.

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end

1M"q(V /usersI 1.10L

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# root 'welcome#index'

1

root 'application#hello'

ApplicationController hellodLg UsersController indexdI 2.3q ApplicationController1 hellodd

.x 2.3 UsersControllerp=config/routes.rb


resources :users

root 'users#index'

.

.

.

end

2.2.1 6 UsersControllerdII 2.4 class UsersController < ApplicationController Ruby 2.3.4 VC4.4 zC

.x 2.4i.app/controllers/users_controller.rb

class UsersController < ApplicationController

.

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def index

.

.

.

end

def show

.

.

.

end

def new

.

.

.

end

def edit

.

.

.

46 - 2 S

end

def create

.

.

.

end

def update

.

.

.

end

def destroy

.

.

.

end

end

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HTTP URL p= =

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GET /users/1 show ID " 1

GET /users/new new

POST /users create

GET /users/1/edit edit ID " 1

PATCH /users/1 update ID " 1

DELETE /users/1 destroy ID " 1

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end

.

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end

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end

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7. Rails g PUT\ HTTP PATCH

48 - 2 S

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Name

Email

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invoke active_record

create db/migrate/20140821012832_create_microposts.rb

create app/models/micropost.rb

invoke test_unit

create test/models/micropost_test.rb

create test/fixtures/microposts.yml

invoke resource_route

route resources :microposts

invoke scaffold_controller

create app/controllers/microposts_controller.rb

invoke erb

create app/views/microposts

create app/views/microposts/index.html.erb

create app/views/microposts/edit.html.erb

create app/views/microposts/show.html.erb

create app/views/microposts/new.html.erb

create app/views/microposts/_form.html.erb

invoke test_unit

create test/controllers/microposts_controller_test.rb

invoke helper

create app/helpers/microposts_helper.rb

invoke test_unit

create test/helpers/microposts_helper_test.rb

invoke jbuilder

create app/views/microposts/index.json.jbuilder

create app/views/microposts/show.json.jbuilder

invoke assets

invoke coffee

create app/assets/javascripts/microposts.js.coffee

invoke scss

create app/assets/stylesheets/microposts.css.scss

invoke scss

identical app/assets/stylesheets/scaffolds.css.scss

Spring J

2.2 Lg


== CreateMicroposts: migrating ===============================================

-- create_table(:microposts)

-> 0.0023s

== CreateMicroposts: migrated (0.0026s) ======================================

8. gJ,g generate Micropost

50 - 2 S

LKg[ 2.2.1 C1e1V Rails M"I 2.89[resources :micropsts URL MicropostsController 2.3

.x 2.8Rails ybconfig/routes.rb


resources :microposts

resources :users

.

.

.

end

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HTTP URL p= =

GET /microposts index

GET /microposts/1 show ID " 1

GET /microposts/new new

POST /microposts create

GET /microposts/1/edit edit ID " 1

PATCH /microposts/1 update ID " 1

DELETE /microposts/1 destroy ID " 1

MicropostsControllerII 2.91 UsersController Microp-ostsController(II 2.4A&1 REST (

.x 2.9s MicropostsControllerapp/controllers/microposts_controller.rb

class MicropostsController < ApplicationController

.

.

.

def index

.

.

.

end

def show

.

9. II 2.8V" Ruby V

2.3. y - 51

..

end

def new

.

.

.

end

def edit

.

.

.

end

def create

.

.

.

end

def update

.

.

.

end

def destroy

.

.

.

end

end

L/microposts/new; 2.12

1o user_id" 122.2.1 2.13[

52 - 2 S

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Rails gvalida-tion" 140 Twitter LKg IDE app/models/micropost.rbI 2.10I

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class Micropost < ActiveRecord::Base

validates :content, length: { maximum: 140 }

end

ILV 6.2 CL 140 d1 2.14Rails Vp17.3.3 VCp

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2.3.3.y

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.x 2.11yapp/models/user.rb

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has_many :microposts

end

.x 2.12y app/models/micropost.rb


belongs_to :user

validates :content, length: { maximum: 140 }

end

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11 12 LVg(V Twitter[LKconsole( Rails > first_user = User.first

=> #

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=> [#, #]

>> micropost = first_user.microposts.first # Micropost.first would also work.

=> #

>> micropost.user

=> #

>> exit

I1 exitea,K Ctrl-D 11 Lg first_user.micropostsActive Record V user_id first_userID1 11 12 LV-

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2.3. y - 55

2.3.4.


.

.

.

end

.x 2.16MicropostsControllerapp/controllers/microposts_controller.rb

class MicropostsController < ApplicationController

.

.

.

end

.x 2.17ApplicationControllerapp/controllers/application_controller.rb

class ApplicationController < ActionController::Base

.

.

.

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$ git commit -m "Finish toy app"

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belongs_to :user

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presence: true

end

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validates FILL_IN, presence: true

validates FILL_IN, presence: true

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# Ruby on Rails Tutorial: sample application

This is the sample application for the

[*Ruby on Rails Tutorial:

Learn Web Development with Rails*](http://www.railstutorial.org/)

by [Michael Hartl](http://www.michaelhartl.com/).

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route get 'static_pages/help'

route get 'static_pages/home'

invoke erb

create app/views/static_pages

create app/views/static_pages/home.html.erb

create app/views/static_pages/help.html.erb

invoke test_unit

create test/controllers/static_pages_controller_test.rb

invoke helper

create app/helpers/static_pages_helper.rb

invoke test_unit

create test/helpers/static_pages_helper_test.rb

invoke assets

invoke coffee

create app/assets/javascripts/static_pages.js.coffee

invoke scss

create app/assets/stylesheets/static_pages.css.scss

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require 'test_helper'

class StaticPagesControllerTest < ActionController::TestCase

test "should get home" do

get :home

assert_response :success

end

test "should get help" do

get :help


end

test "should get about" do

get :about


end

end

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def home

end

def help

end

def about

end

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def setup

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end


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assert_select "title", "Help | #{@base_title}"

end


get :about


assert_select "title", "About | #{@base_title}"

end

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3.7.3.> Guard p

g rake testJ@J"1mLKg GuardGuard VMxeq1 stat-ic_pages_controller_test.rb& Guard VMLK Guard home.html.erbMq, static_pages_controller_test.rb

I 3.21 guard gemKL

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Writing new Guardfile to /home/ubuntu/workspace/sample_app/Guardfile

00:51:32 - INFO - minitest guard added to Guardfile, feel free to edit it

GuardfileM Guard I3.42MK

.x 3.42D Guardfile

# Defines the matching rules for Guard.

guard :minitest, spring: true, all_on_start: false do

watch(%r{^test/(.*)/?(.*)_test\.rb$})

watch('test/test_helper.rb') { 'test' }

watch('config/routes.rb') { integration_tests }

watch(%r{^app/models/(.*?)\.rb$}) do |matches|

"test/models/#{matches[1]}_test.rb"

end

watch(%r{^app/controllers/(.*?)_controller\.rb$}) do |matches|

3.7. - 91

resource_tests(matches[1])

end

watch(%r{^app/views/([^/]*?)/.*\.html\.erb$}) do |matches|

["test/controllers/#{matches[1]}_controller_test.rb"] +

integration_tests(matches[1])

end

watch(%r{^app/helpers/(.*?)_helper\.rb$}) do |matches|

integration_tests(matches[1])

end

watch('app/views/layouts/application.html.erb') do

'test/integration/site_layout_test.rb'

end

watch('app/helpers/sessions_helper.rb') do

integration_tests

g Guard "1 Spring Git spring/M .gitignoreM Git M7 IDE &z

M 3.9

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# See https://help.github.com/articles/ignoring-files for more about ignoring

# files.

#

# If you find yourself ignoring temporary files generated by your text editor

# or operating system, you probably want to add a global ignore instead:

# git config --global core.excludesfile '~/.gitignore_global'

# Ignore bundler config.

/.bundle

# Ignore the default SQLite database.

/db/*.sqlite3

/db/*.sqlite3-journal

# Ignore all logfiles and tempfiles.

/log/*.log

/tmp

# Ignore Spring files.

/spring/*.pid

d.Spring Spring Ve 3.4 Spring

3.4Unix

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p ID pidKg killJ pid kill p 9

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4 Rails Ruby

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\1

"1L'" full_title'full_titleRuby on Rails Tutorial Sample App'1I 4.21

.x 4.2 full_titleqapp/helpers/application_helper.rb

module ApplicationHelper

# def full_title(page_title = '')

base_title = "Ruby on Rails Tutorial Sample App"

if page_title.empty?

base_title

else

"#{page_title} | #{base_title}"

end

end

end

'1LK


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1. Mh" app/helper/static_pages_helper.rbhLg full_titleKM app/helper/application_helper.rb

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true %>

true %>

"1dLHomeoLqII 4.4 "Home"ez1-I 3.38q1' @base_title setup

.x 4.4D REDtest/controllers/static_pages_controller_test.rb




get :home


assert_select "title", "Ruby on Rails Tutorial Sample App"

end


get :help


assert_select "title", "Help | Ruby on Rails Tutorial Sample App"

end


get :about


assert_select "title", "About | Ruby on Rails Tutorial Sample App"

end

end

LM

.x 4.5RED



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Sample App



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>> "" # => ""

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>> "foo" + "bar" # => "foobar"

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4.2. - 101

>> first_name = "Michael" # F=> "Michael"

>> "#{first_name} Hartl" # F=> "Michael Hartl"

L "Michael"v first_name "#{first_name} Hartl"L,K v

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=> "Michael"

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=> "Hartl"

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>> "#{first_name} #{last_name}" # =F=> "Michael Hartl"

dw6gv " "

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>> '#{foo} bar' # xF==> "\#{foo} bar"

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>> '\n' # n F=> "\\n"

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=> "Newlines (\\n) and tabs (\\t) both use the backslash character \\."

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Ruby nilLV 4.4.2 C'.e;h

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W'5 K empty?

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=> false

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=> true

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>> s = "foobar"

>> if s.empty?

>> "The string is empty"

>> else

>> "The string is nonempty"

>> end

=> "The string is nonempty"

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5. ( Ruby 5,"

4.2. - 103

>> if s.nil?

>> "The variable is nil"

>> elsif s.empty?

>> "The string is empty"

>> elsif s.include?("foo")

>> "The string includes 'foo'"

>> end

=> "The string includes 'foo'"

vKg &&|| !dg

>> x = "foo"

=> "foo"

>> y = ""

=> ""

>> puts "Both strings are empty" if x.empty? && y.empty?

=> nil

>> puts "One of the strings is empty" if x.empty? || y.empty?

"One of the strings is empty"

=> nil

>> puts "x is not empty" if !x.empty?

"x is not empty"

=> nil

" Ruby & nil,K,K$hto_sKOa

>> nil.to_s

=> ""

LK chain

>> nil.empty?

NoMethodError: undefined method `empty?' for nil:NilClass

>> nil.to_s.empty? # => true

Lnil empty?\ nil.to_sK

K"e

>> "foo".nil?

=> false

>> "".nil?

=> false

>> nil.nil?

=> true

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puts "x is not empty" if !x.empty?

1 ifeK if"v unless,K&

104 - 4 Rails Ruby

>> string = "foobar"

>> puts "The string '#{string}' is nonempty." unless string.empty?

The string 'foobar' is nonempty.

=> nil

L nil1 false( Ruby v"xLKg !!dbang bangzdv

>> !!nil

=> false

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>> !!0

=> true

4.2.4.

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>> def string_message(str = '')

>> if str.empty?

>> "It's an empty string!"

>> else

>> "The string is nonempty."

>> end

>> end

=> :string_message

>> puts string_message("foobar")

The string is nonempty.

>> puts string_message("")

It's an empty string!

>> puts string_message


JKK" def string_message(str ='')i1v Kstrgv

Ruby vvv `6 str" Ruby ,KvN

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>> end

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4.2. - 105

A&'K strOh the_function_argument\d

>> def string_message(the_function_argument = '')

>> if the_function_argument.empty?

>> "It's an empty string!"

>> else

>> "The string is nonempty."

>> end

>> end

=> nil

>> puts string_message("")


>> puts string_message("foobar")

The string is nonempty.

4.2.5.q

LI 4.2 full_title6(I 4.9

.x 4.9 full_titleapp/helpers/application_helper.rb

module ApplicationHelper

# # def full_title(page_title = '') # ~base_title = "Ruby on Rails Tutorial Sample App" # Fif page_title.empty? # base_title # F

else

"#{page_title} | #{base_title}" # Fend

end

end

'v v'1Kgmodule ApplicationHelper"Li1LKg includeH Ruby e'\V Rails "Lfull_titleg

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d split ,K)Oa

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=> ["foo", "bar", "baz"]

-Ruby ,E 05 1j

>> a = [42, 8, 17]

=> [42, 8, 17]

>> a[0] # Ruby >L=> 42

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>> a[-1] # 0=> 17

LRuby g1(Ruby ";i17

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=> true

7. Ig second Ruby ' Rails Kg"Rails V Rails Ruby

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>> x == 1

=> false

>> x != 1

=> true

>> x >= 1

=> true

>> x < 1

=> false

1 lengthI(KH

>> a

=> [42, 8, 17]

>> a.empty?

=> false

>> a.include?(42)

=> true

>> a.sort

=> [8, 17, 42]

>> a.reverse

=> [17, 8, 42]

>> a.shuffle

=> [17, 42, 8]

>> a

=> [42, 8, 17]

q avqvgbang(K&"dbang

>> a

=> [42, 8, 17]

>> a.sort!

=> [8, 17, 42]

>> a

=> [8, 17, 42]

Kg pushgN a.push(6) # 6 nh=> [42, 8, 17, 6]

>> a [42, 8, 17, 6, 7]

>> a > a

=> [42, 8, 17, 7, "foo", "bar"]

>> a.join # => "428177foobar"

108 - 4 Rails Ruby

>> a.join(', ') # => "42, 8, 17, 7, foo, bar"

[vrangeg to_a

>> 0..9

=> 0..9

>> 0..9.to_a # to_a 9 NoMethodError: undefined method `to_a' for 9:Fixnum

>> (0..9).to_a # to_a r;F=> [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

0..9v5L

v

>> a = %w[foo bar baz quux] # %w dL=> ["foo", "bar", "baz", "quux"]

>> a[0..2]

=> ["foo", "bar", "baz"]

vvg -1 Ev

>> a = (0..9).to_a

=> [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

>> a[2..(a.length-1)] # >=> [2, 3, 4, 5, 6, 7, 8, 9]

>> a[2..-1] # > -1=> [2, 3, 4, 5, 6, 7, 8, 9]

v,Kg

>> ('a'..'e').to_a

=> ["a", "b", "c", "d", "e"]

4.3.2.

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>> (1..5).each { |i| puts 2 * i }

2

4

6

8

10

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?> puts 2 * i

>> end

2

4

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8

10

=> 1..5

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>> (1..5).each do |number|

?> puts 2 * number

>> puts '-'

>> end

2

-

4

-

6

-

8

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10

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=> 1..5

I numberI1 ieKgOav

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>> 3.times { puts "Betelgeuse!" } # 3.times "Betelgeuse!"

"Betelgeuse!"

"Betelgeuse!"

=> 3

>> (1..5).map { |i| i**2 } # ** => [1, 4, 9, 16, 25]

>> %w[a b c] # V%w dL=> ["a", "b", "c"]

>> %w[a b c].map { |char| char.upcase }

=> ["A", "B", "C"]

>> %w[A B C].map { |char| char.downcase }

=> ["a", "b", "c"]

KmapvIJmapdg

8. closure@V;1;

110 - 4 Rails Ruby

>> %w[A B C].map { |char| char.downcase }

=> ["a", "b", "c"]

>> %w[A B C].map(&:downcase)

=> ["a", "b", "c"]

14.3.3 VC Rails\@L1 Ruby I

ghLI 4.4h


get :home


assert_select "title", "Ruby on Rails Tutorial Sample App"

end

,E doK#`test MV

L 1.5.4 5g Ruby I

('a'..'z').to_a.shuffle[0..7].join

L

>> ('a'..'z').to_a # O=> ["a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o",

"p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z"]

>> ('a'..'z').to_a.shuffle # => ["c", "g", "l", "k", "h", "z", "s", "i", "n", "d", "y", "u", "t", "j", "q",

"b", "r", "o", "f", "e", "w", "v", "m", "a", "x", "p"]

>> ('a'..'z').to_a.shuffle[0..7] # [k 8 L=> ["f", "w", "i", "a", "h", "p", "c", "x"]

>> ('a'..'z').to_a.shuffle[0..7].join # [L=> "mznpybuj"

4.3.3.

Hash6g;Perl"z)KgOahKg

>> user = {} # {} => {}

>> user["first_name"] = "Michael" # "first_name"F "Michael"=> "Michael"

>> user["last_name"] = "Hartl" # "last_name"F "Hartl"=> "Hartl"

>> user["first_name"] # L8=> "Michael"

>> user # => {"last_name"=>"Hartl", "first_name"=>"Michael"}

4.3. R- - 111

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'gv'

>> user = { "first_name" => "Michael", "last_name" => "Hartl" }

=> {"last_name"=>"Hartl", "first_name"=>"Michael"}

I1 Ruby 1V;"A&;n Ruby =1

"g Rails Symbol h:nameeK 10

>> "name".split('')

=> ["n", "a", "m", "e"]

>> :name.split('')

NoMethodError: undefined method `split' for :name:Symbol

>> "foobar".reverse

=> "raboof"

>> :foobar.reverse

NoMethodError: undefined method `reverse' for :foobar:Symbol

Ruby H Rails KeV- g

>> :foo-bar

NameError: undefined local variable or method `bar' for main:Object

>> :2foo

SyntaxError

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LK' user

>> user = { :name => "Michael Hartl", :email => "[email protected]" }

=> {:name=>"Michael Hartl", :email=>"[email protected]"}

>> user[:name] # :name F=> "Michael Hartl"

>> user[:password] # F=> nil

EhK'v nil

9. Ruby 1.9 KVoj10. g"f

112 - 4 Rails Ruby

"1Ruby 1.9 "'1

>> h1 = { :name => "Michael Hartl", :email => "[email protected]" }


>> h2 = { name: "Michael Hartl", email: "[email protected]" }


>> h1 == h2

=> true

5 1:

{ name: "Michael Hartl", email: "[email protected]" }

1Hh JavaScript Rails ,gKeL@" :name\ name:':name name:d{ :name "Michael Hartl" } { name: "Michael Hartl" }g :name

vKOaI 4.10

.x 4.10

>> params = {} # paramsparameters => {}

>> params[:user] = { name: "Michael Hartl", email: "[email protected]" }


>> params

=> {:user=>{:name=>"Michael Hartl", :email=>"[email protected]"}}

>> params[:user][:email]

=> "[email protected]"

Rails g"LE 7.3 V

v, eachh" flashM:success :danger

>> flash = { success: "It worked!", danger: "It failed." }

=> {:success=>"It worked!", :danger=>"It failed."}

>> flash.each do |key, value|

?> puts "Key #{key.inspect} has value #{value.inspect}"

>> end

Key :success has value "It worked!"

Key :danger has value "It failed."

each eachvK eachVKv"]

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>> puts (1..5).to_a # F1

2

3

4

4.3. R- - 113

5>> puts (1..5).to_a.inspect # [[1, 2, 3, 4, 5]

>> puts :name, :name.inspect

name

:name

>> puts "It worked!", "It worked!".inspect

It worked!

"It worked!"

m"g inspectg"p11

>> p :name # 2 'puts :name.inspect':name

4.3.4.N CSS .

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true %>

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>> s.class

=> String

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1g(LKgNnamed constructornew14

>> s = String.new("foobar") # S=> "foobar"

>> s.class

=> String

>> s == "foobar"

=> true

IgNL

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>> a = Array.new([1, 3, 2])

=> [1, 3, 2]

1 Array.newvHash.newvv

>> h = Hash.new

=> {}

>> h[:foo] # :foo F=> nil

>> h = Hash.new(0) # 0 nil=> {}

>> h[:foo]

=> 0

h newclass method new,zhinstancehh lengthhinstance method

4.4.2.

-VLKg superclass

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=> "foobar"

>> s.class # s => String

>> s.class.superclass # String => Object

>> s.class.superclass.superclass # Ruby 1.9 > BasicObject ==> BasicObject

>> s.class.superclass.superclass.superclass

=> nil

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=> false

>> w.palindrome?("level")

=> true

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>> self == self.reverse # self .>> end

>> end

=> nil

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>> s.palindrome? # Word ?0 palindrome? => true

>> s.length # Word ?=> 5

Word StringLK

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=> Word

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=> String

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=> Object

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>> end

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=> true

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class StaticPagesController < ApplicationController

def home

end

def help

end

4.4. Ruby - 119

def about

end

end

eK;I1StaticPagesController Applica-tionController homehelp about" Rails V Rails KLK16

>> controller = StaticPagesController.new

=> #

>> controller.class

=> StaticPagesController

>> controller.class.superclass

=> ApplicationController

>> controller.class.superclass.superclass

=> ActionController::Base

>> controller.class.superclass.superclass.superclass

=> ActionController::Metal

>> controller.class.superclass.superclass.superclass.superclass

=> AbstractController::Base

>> controller.class.superclass.superclass.superclass.superclass.superclass

=> Object

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>> controller.home

=> nil

homedv" nil"

dvvL 3 homedv\Oa StaticPagesController.new&4

6Rails Ruby \ Rails Ruby; Rails Ruby ,;6 Rails Rails Ruby -

16. ed,LA&E 2005 g Ruby on Rai

Documents

Ruby on Rails tutorial 3rd 中文版