scaffoldによる各種リソース自動生成

$ rails generate scaffold Post name:string title:string content:text
$ rake db:migrate

記事一覧画面へのリンクを貼る

<h1>Home#index</h1>
<p>Find me in app/views/home/index.html.erb</p>
<h1>Hello, Rails!</h1>
<%= link_to "My Blog", posts_path %>

バリデーションを追加する

class Post < ActiveRecord::Base
  validates :name,  :presence => true
  validates :title, :presence => true, :length => { :minimum => 5 }
end

コメント機能を実装する

$ rails generate model Comment commenter:string body:text post:references
$ rake db:migrate

class Post < ActiveRecord::Base
  validates :name,  :presence => true
  validates :title, :presence => true, :length => { :minimum => 5 }
 
  has_many :comments
end

resources :posts do
  resources :comments
end

$ rails generate controller Comments

<h2>コメント</h2>
<% @post.comments.each do |comment| %>
  <p>
    <%= comment.commenter %>: <%= comment.body %>
    <%= link_to '削除', [comment.post, comment],
               :confirm => 'よろしいですか？',
               :method => :delete %>

  </p>
<% end %>

<h2>コメントを書く</h2>
<%= form_for([@post, @post.comments.build]) do |f| %>
  <div class="field">
    <%= f.label :commenter %><br />
    <%= f.text_field :commenter %>
  </div>
  <div class="field">
    <%= f.label :body %><br />
    <%= f.text_area :body %>
  </div>
  <div class="actions">
    <%= f.submit %>
  </div>
<% end %>

class CommentsController < ApplicationController
  def create
    @post = Post.find(params[:post_id])
    @comment = @post.comments.create(params[:comment])
    redirect_to post_path(@post)
  end

  def destroy
    @post = Post.find(params[:post_id])
    @comment = @post.comments.find(params[:id])
    @comment.destroy
    redirect_to post_path(@post)
  end
end

参考