Rails 入門指南

$ ruby --version
ruby 2.7.0

$ sqlite3 --version

$ gem install rails

$ rails --version

$ rails new blog

$ cd blog

$ bin/rails server

Rails.application.routes.draw do
  get "/articles", to: "articles#index"

  # 有關此文件中可用的DSL的詳細信息，請參閱https://guides.rubyonrails.org/routing.html
end

$ bin/rails generate controller Articles index --skip-routes

create  app/controllers/articles_controller.rb
invoke  erb
create    app/views/articles
create    app/views/articles/index.html.erb
invoke  test_unit
create    test/controllers/articles_controller_test.rb
invoke  helper
create    app/helpers/articles_helper.rb
invoke    test_unit

class ArticlesController < ApplicationController
  def index
  end
end

<h1>Hello, Rails!</h1>

Rails.application.routes.draw do
  root "articles#index"

  get "/articles", to: "articles#index"
end

require "application_controller" # 不要這樣做。

$ bin/rails generate model Article title:string body:text

invoke  active_record
create    db/migrate/<timestamp>_create_articles.rb
create    app/models/article.rb
invoke    test_unit
create      test/models/article_test.rb
create      test/fixtures/articles.yml

class CreateArticles < ActiveRecord::Migration[7.0]
  def change
    create_table :articles do |t|
      t.string :title
      t.text :body

      t.timestamps
    end
  end
end

$ bin/rails db:migrate

==  CreateArticles: migrating ===================================
-- create_table(:articles)
   -> 0.0018s
==  CreateArticles: migrated (0.0018s) ==========================

$ bin/rails console

Loading development environment (Rails 7.0.0)
irb(main):001:0>

irb> article = Article.new(title: "Hello Rails", body: "I am on Rails!")

irb> article.save
(0.1ms)  begin transaction
Article Create (0.4ms)  INSERT INTO "articles" ("title", "body", "created_at", "updated_at") VALUES (?, ?, ?, ?)  [["title", "Hello Rails"], ["body", "I am on Rails!"], ["created_at", "2020-01-18 23:47:30.734416"], ["updated_at", "2020-01-18 23:47:30.734416"]]
(0.9ms)  commit transaction
=> true

irb> article
=> #<Article id: 1, title: "Hello Rails", body: "I am on Rails!", created_at: "2020-01-18 23:47:30", updated_at: "2020-01-18 23:47:30">

irb> Article.find(1)
=> #<Article id: 1, title: "Hello Rails", body: "I am on Rails!", created_at: "2020-01-18 23:47:30", updated_at: "2020-01-18 23:47:30">

irb> Article.all
=> #<ActiveRecord::Relation [#<Article id: 1, title: "Hello Rails", body: "I am on Rails!", created_at: "2020-01-18 23:47:30", updated_at: "2020-01-18 23:47:30">]>

class ArticlesController < ApplicationController
  def index
    @articles = Article.all
  end
end

<h1>Articles</h1>

<ul>
  <% @articles.each do |article| %>
    <li>
      <%= article.title %>
    </li>
  <% end %>
</ul>

Rails.application.routes.draw do
  root "articles#index"

  get "/articles", to: "articles#index"
  get "/articles/:id", to: "articles#show"
end

class ArticlesController < ApplicationController
  def index
    @articles = Article.all
  end

  def show
    @article = Article.find(params[:id])
  end
end

<h1>文章</h1>

<ul>
  <% @articles.each do |article| %>
    <li>
      <a href="/articles/<%= article.id %>">
        <%= article.title %>
      </a>
    </li>
  <% end %>
</ul>

Rails.application.routes.draw do
  root "articles#index"

  resources :articles
end

$ bin/rails routes
      Prefix Verb   URI Pattern                  Controller#Action
        root GET    /                            articles#index
    articles GET    /articles(.:format)          articles#index
 new_article GET    /articles/new(.:format)      articles#new
     article GET    /articles/:id(.:format)      articles#show
             POST   /articles(.:format)          articles#create
edit_article GET    /articles/:id/edit(.:format) articles#edit
             PATCH  /articles/:id(.:format)      articles#update
             DELETE /articles/:id(.:format)      articles#destroy

<h1>文章</h1>

<ul>
  <% @articles.each do |article| %>
    <li>
      <a href="<%= article_path(article) %>">
        <%= article.title %>
      </a>
    </li>
  <% end %>
</ul>

<h1>文章</h1>

<ul>
  <% @articles.each do |article| %>
    <li>
      <%= link_to article.title, article %>
    </li>
  <% end %>
</ul>

class ArticlesController < ApplicationController
  def index
    @articles = Article.all
  end

  def show
    @article = Article.find(params[:id])
  end

  def new
    @article = Article.new
  end

  def create
    @article = Article.new(title: "...", body: "...")

    if @article.save
      redirect_to @article
    else
      render :new, status: :unprocessable_entity
    end
  end
end

<h1>新文章</h1>

<%= form_with model: @article do |form| %>
  <div>
    <%= form.label :title %><br>
    <%= form.text_field :title %>
  </div>

  <div>
    <%= form.label :body %><br>
    <%= form.text_area :body %>
  </div>

  <div>
    <%= form.submit %>
  </div>
<% end %>

<form action="/articles" accept-charset="UTF-8" method="post">
  <input type="hidden" name="authenticity_token" value="...">

  <div>
    <label for="article_title">標題</label><br>
    <input type="text" name="article[title]" id="article_title">
  </div>

  <div>
    <label for="article_body">內容</label><br>
    <textarea name="article[body]" id="article_body"></textarea>
  </div>

  <div>
    <input type="submit" name="commit" value="創建文章" data-disable-with="創建文章">
  </div>
</form>

class ArticlesController < ApplicationController
  def index
    @articles = Article.all
  end

  def show
    @article = Article.find(params[:id])
  end

  def new
    @article = Article.new
  end

  def create
    @article = Article.new(article_params)

    if @article.save
      redirect_to @article
    else
      render :new, status: :unprocessable_entity
    end
  end

  private
    def article_params
      params.require(:article).permit(:title, :body)
    end
end

class Article < ApplicationRecord
  validates :title, presence: true
  validates :body, presence: true, length: { minimum: 10 }
end

<h1>新增文章</h1>

<%= form_with model: @article do |form| %>
  <div>
    <%= form.label :title %><br>
    <%= form.text_field :title %>
    <% @article.errors.full_messages_for(:title).each do |message| %>
      <div><%= message %></div>
    <% end %>
  </div>

  <div>
    <%= form.label :body %><br>
    <%= form.text_area :body %><br>
    <% @article.errors.full_messages_for(:body).each do |message| %>
      <div><%= message %></div>
    <% end %>
  </div>

  <div>
    <%= form.submit %>
  </div>
<% end %>

  def new
    @article = Article.new
  end

  def create
    @article = Article.new(article_params)

    if @article.save
      redirect_to @article
    else
      render :new, status: :unprocessable_entity
    end
  end

<h1>文章</h1>

<ul>
  <% @articles.each do |article| %>
    <li>
      <%= link_to article.title, article %>
    </li>
  <% end %>
</ul>

<%= link_to "新增文章", new_article_path %>

class ArticlesController < ApplicationController
  def index
    @articles = Article.all
  end

  def show
    @article = Article.find(params[:id])
  end

  def new
    @article = Article.new
  end

  def create
    @article = Article.new(article_params)

    if @article.save
      redirect_to @article
    else
      render :new, status: :unprocessable_entity
    end
  end

  def edit
    @article = Article.find(params[:id])
  end

  def update
    @article = Article.find(params[:id])

    if @article.update(article_params)
      redirect_to @article
    else
      render :edit, status: :unprocessable_entity
    end
  end

  private
    def article_params
      params.require(:article).permit(:title, :body)
    end
end

<%= form_with model: article do |form| %>
  <div>
    <%= form.label :title %><br>
    <%= form.text_field :title %>
    <% article.errors.full_messages_for(:title).each do |message| %>
      <div><%= message %></div>
    <% end %>
  </div>

  <div>
    <%= form.label :body %><br>
    <%= form.text_area :body %><br>
    <% article.errors.full_messages_for(:body).each do |message| %>
      <div><%= message %></div>
    <% end %>
  </div>

  <div>
    <%= form.submit %>
  </div>
<% end %>

<h1>新文章</h1>

<%= render "form", article: @article %>

<h1>編輯文章</h1>

<%= render "form", article: @article %>

<h1><%= @article.title %></h1>

<p><%= @article.body %></p>

<ul>
  <li><%= link_to "編輯", edit_article_path(@article) %></li>
</ul>

class ArticlesController < ApplicationController
  def index
    @articles = Article.all
  end

  def show
    @article = Article.find(params[:id])
  end

  def new
    @article = Article.new
  end

  def create
    @article = Article.new(article_params)

    if @article.save
      redirect_to @article
    else
      render :new, status: :unprocessable_entity
    end
  end

  def edit
    @article = Article.find(params[:id])
  end

  def update
    @article = Article.find(params[:id])

    if @article.update(article_params)
      redirect_to @article
    else
      render :edit, status: :unprocessable_entity
    end
  end

  def destroy
    @article = Article.find(params[:id])
    @article.destroy

    redirect_to root_path, status: :see_other
  end

  private
    def article_params
      params.require(:article).permit(:title, :body)
    end
end

<h1><%= @article.title %></h1>

<p><%= @article.body %></p>

<ul>
  <li><%= link_to "編輯", edit_article_path(@article) %></li>
  <li><%= link_to "刪除", article_path(@article), data: {
                    turbo_method: :delete,
                    turbo_confirm: "確定要刪除嗎？"
                  } %></li>
</ul>

$ bin/rails generate model Comment commenter:string body:text article:references

class Comment < ApplicationRecord
  belongs_to :article
end

class CreateComments < ActiveRecord::Migration[7.0]
  def change
    create_table :comments do |t|
      t.string :commenter
      t.text :body
      t.references :article, null: false, foreign_key: true

      t.timestamps
    end
  end
end

$ bin/rails db:migrate

==  CreateComments: migrating =================================================
-- create_table(:comments)
   -> 0.0115s
==  CreateComments: migrated (0.0119s) ========================================

class Comment < ApplicationRecord
  belongs_to :article
end

class Article < ApplicationRecord
  has_many :comments

  validates :title, presence: true
  validates :body, presence: true, length: { minimum: 10 }
end

Rails.application.routes.draw do
  root "articles#index"

  resources :articles do
    resources :comments
  end
end

$ bin/rails generate controller Comments

<h1><%= @article.title %></h1>

<p><%= @article.body %></p>

<ul>
  <li><%= link_to "Edit", edit_article_path(@article) %></li>
  <li><%= link_to "Destroy", article_path(@article), data: {
                    turbo_method: :delete,
                    turbo_confirm: "Are you sure?"
                  } %></li>
</ul>

<h2>Add a comment:</h2>
<%= form_with model: [ @article, @article.comments.build ] do |form| %>
  <p>
    <%= form.label :commenter %><br>
    <%= form.text_field :commenter %>
  </p>
  <p>
    <%= form.label :body %><br>
    <%= form.text_area :body %>
  </p>
  <p>
    <%= form.submit %>
  </p>
<% end %>

class CommentsController < ApplicationController
  def create
    @article = Article.find(params[:article_id])
    @comment = @article.comments.create(comment_params)
    redirect_to article_path(@article)
  end

  private
    def comment_params
      params.require(:comment).permit(:commenter, :body)
    end
end

<h1><%= @article.title %></h1>

<p><%= @article.body %></p>

<ul>
  <li><%= link_to "編輯", edit_article_path(@article) %></li>
  <li><%= link_to "刪除", article_path(@article), data: {
                    turbo_method: :delete,
                    turbo_confirm: "你確定嗎？"
                  } %></li>
</ul>

<h2>評論</h2>
<% @article.comments.each do |comment| %>
  <p>
    <strong>評論者：</strong>
    <%= comment.commenter %>
  </p>

  <p>
    <strong>評論內容：</strong>
    <%= comment.body %>
  </p>
<% end %>

<h2>新增評論：</h2>
<%= form_with model: [ @article, @article.comments.build ] do |form| %>
  <p>
    <%= form.label :commenter %><br>
    <%= form.text_field :commenter %>
  </p>
  <p>
    <%= form.label :body %><br>
    <%= form.text_area :body %>
  </p>
  <p>
    <%= form.submit %>
  </p>
<% end %>

<p>
  <strong>評論者：</strong>
  <%= comment.commenter %>
</p>

<p>
  <strong>評論內容：</strong>
  <%= comment.body %>
</p>

<h1><%= @article.title %></h1>

<p><%= @article.body %></p>

<ul>
  <li><%= link_to "編輯", edit_article_path(@article) %></li>
  <li><%= link_to "刪除", article_path(@article), data: {
                    turbo_method: :delete,
                    turbo_confirm: "你確定嗎？"
                  } %></li>
</ul>

<h2>評論</h2>
<%= render @article.comments %>

<h2>新增評論：</h2>
<%= form_with model: [ @article, @article.comments.build ] do |form| %>
  <p>
    <%= form.label :commenter %><br>
    <%= form.text_field :commenter %>
  </p>
  <p>
    <%= form.label :body %><br>
    <%= form.text_area :body %>
  </p>
  <p>
    <%= form.submit %>
  </p>
<% end %>

<%= form_with model: [ @article, @article.comments.build ] do |form| %>
  <p>
    <%= form.label :commenter %><br>
    <%= form.text_field :commenter %>
  </p>
  <p>
    <%= form.label :body %><br>
    <%= form.text_area :body %>
  </p>
  <p>
    <%= form.submit %>
  </p>
<% end %>

<h1><%= @article.title %></h1>

<p><%= @article.body %></p>

<ul>
  <li><%= link_to "編輯", edit_article_path(@article) %></li>
  <li><%= link_to "刪除", article_path(@article), data: {
                    turbo_method: :delete,
                    turbo_confirm: "你確定嗎？"
                  } %></li>
</ul>

<h2>評論</h2>
<%= render @article.comments %>

<h2>新增評論：</h2>
<%= render 'comments/form' %>

app/controllers/concerns
app/models/concerns

$ bin/rails generate migration AddStatusToArticles status:string
$ bin/rails generate migration AddStatusToComments status:string

$ bin/rails db:migrate

  private
    def article_params
      params.require(:article).permit(:title, :body, :status)
    end

  private
    def comment_params
      params.require(:comment).permit(:commenter, :body, :status)
    end

class Article < ApplicationRecord
  has_many :comments

  validates :title, presence: true
  validates :body, presence: true, length: { minimum: 10 }

  VALID_STATUSES = ['public', 'private', 'archived']

  validates :status, inclusion: { in: VALID_STATUSES }

  def archived?
    status == 'archived'
  end
end

class Comment < ApplicationRecord
  belongs_to :article

  VALID_STATUSES = ['public', 'private', 'archived']

  validates :status, inclusion: { in: VALID_STATUSES }

  def archived?
    status == 'archived'
  end
end

<h1>Articles</h1>

<ul>
  <% @articles.each do |article| %>
    <% unless article.archived? %>
      <li>
        <%= link_to article.title, article %>
      </li>
    <% end %>
  <% end %>
</ul>

<%= link_to "New Article", new_article_path %>

<% unless comment.archived? %>
  <p>
    <strong>Commenter:</strong>
    <%= comment.commenter %>
  </p>

  <p>
    <strong>Comment:</strong>
    <%= comment.body %>
  </p>
<% end %>

module Visible
  def archived?
    status == 'archived'
  end
end

module Visible
  extend ActiveSupport::Concern

  VALID_STATUSES = ['public', 'private', 'archived']

  included do
    validates :status, inclusion: { in: VALID_STATUSES }
  end

  def archived?
    status == 'archived'
  end
end

class Article < ApplicationRecord
  include Visible

  has_many :comments

  validates :title, presence: true
  validates :body, presence: true, length: { minimum: 10 }
end

class Comment < ApplicationRecord
  include Visible

  belongs_to :article
end

module Visible
  extend ActiveSupport::Concern

  VALID_STATUSES = ['public', 'private', 'archived']

  included do
    validates :status, inclusion: { in: VALID_STATUSES }
  end

  class_methods do
    def public_count
      where(status: 'public').count
    end
  end

  def archived?
    status == 'archived'
  end
end

<h1>文章</h1>

我們的博客有 <%= Article.public_count %> 篇文章，並且還在增加中！

<ul>
  <% @articles.each do |article| %>
    <% unless article.archived? %>
      <li>
        <%= link_to article.title, article %>
      </li>
    <% end %>
  <% end %>
</ul>

<%= link_to "新文章", new_article_path %>

<div>
  <%= form.label :status %><br>
  <%= form.select :status, ['public', 'private', 'archived'], selected: 'public' %>
</div>

<p>
  <%= form.label :status %><br>
  <%= form.select :status, ['public', 'private', 'archived'], selected: 'public' %>
</p>

<% unless comment.archived? %>
  <p>
    <strong>評論者：</strong>
    <%= comment.commenter %>
  </p>

  <p>
    <strong>評論：</strong>
    <%= comment.body %>
  </p>

  <p>
    <%= link_to "刪除評論", [comment.article, comment], data: {
                  turbo_method: :delete,
                  turbo_confirm: "確定要刪除嗎？"
                } %>
  </p>
<% end %>

class CommentsController < ApplicationController
  def create
    @article = Article.find(params[:article_id])
    @comment = @article.comments.create(comment_params)
    redirect_to article_path(@article)
  end

  def destroy
    @article = Article.find(params[:article_id])
    @comment = @article.comments.find(params[:id])
    @comment.destroy
    redirect_to article_path(@article), status: :see_other
  end

  private
    def comment_params
      params.require(:comment).permit(:commenter, :body, :status)
    end
end

class Article < ApplicationRecord
  include Visible

  has_many :comments, dependent: :destroy

  validates :title, presence: true
  validates :body, presence: true, length: { minimum: 10 }
end

class ArticlesController < ApplicationController

  http_basic_authenticate_with name: "dhh", password: "secret", except: [:index, :show]

  def index
    @articles = Article.all
  end

  # 省略部分代碼

class CommentsController < ApplicationController

  http_basic_authenticate_with name: "dhh", password: "secret", only: :destroy

  def create
    @article = Article.find(params[:article_id])
    # ...
  end

  # 省略部分代碼