Ruby on Rails - CRUD 2

以下是给每个 Article 对应多个 Comment

1.产生 Comment model
$ rails generate model Comment commenter:string body:text article:references

invoke active_record
create db/migrate/20160727045002_create_comments.rb
create app/models/comment.rb
invoke test_unit
create test/models/comment_test.rb
create test/fixtures/comments.yml

# app/models/comment.rb
class Comment < ActiveRecord::Base
  belongs_to :article
end
 
2.db移植
$ rake db:migrate

3.Article / Comment 间关系 (一对多) 修改
# app/models/article.rb
class Article < ActiveRecord::Base
  has_many :comments
  validates :title, presence: true,
                    length: { minimum: 5 }
end

# config/routes.rb
resources :articles do
  resources :comments
end
 
4.编写 controller
$ rails generate controller Comments

create app/controllers/comments_controller.rb
invoke erb
create app/views/comments
invoke test_unit
create test/controllers/comments_controller_test.rb
invoke helper
create app/helpers/comments_helper.rb
invoke test_unit
invoke assets
invoke coffee
create app/assets/javascripts/comments.coffee
invoke scss
create app/assets/stylesheets/comments.scss

5.其它
# app/views/articles/show.html.erb 
<h2>Comments</h2>
<% @article.comments.each do |comment| %>
  <p><strong>Commenter:</strong><%= comment.commenter %></p>
  <p><strong>Comment:</strong><%= comment.body %></p>
<% end %>
 
<h2>Add a comment:</h2>
<%= form_for([@article, @article.comments.build]) do |f| %>
  <p><%= f.label :commenter %><br><%= f.text_field :commenter %></p>
  <p><%= f.label :body %><br><%= f.text_area :body %></p>
  <p><%= f.submit %></p>
<% end %>

# app/controllers/comments_controller.rb
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

6.重构 
# app/views/comments/_comment.html.erb
<p><strong>Commenter:</strong><%= comment.commenter %></p>
<p><strong>Comment:</strong><%= comment.body %></p>

# app/views/comments/_form.html.erb
<%= form_for([@article, @article.comments.build]) do |f| %>
  <p><%= f.label :commenter %><br><%= f.text_field :commenter %></p>
  <p><%= f.label :body %><br><%= f.text_area :body %></p>
  <p><%= f.submit %></p>
<% end %>

# app/views/articles/show.html.erb
<h2>Comments</h2>
<%= render @article.comments %>
<h2>Add a comment:</h2>
<%= render "comments/form" %>

7.删除 comment 
# app/views/comments/_comment.html.erb
<p><strong>Commenter:</strong><%= comment.commenter %></p>
<p><strong>Comment:</strong><%= comment.body %></p>
<p>
  <%= link_to 'Destroy Comment', [comment.article, comment],
               method: :delete,
               data: { confirm: 'Are you sure?' } %>
</p>

# app/controllers/comments_controller.rb
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)
  end

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

# app/models/article.rb
class Article < ActiveRecord::Base
  has_many :comments, dependent: :destroy
  validates :title, presence: true,
                    length: { minimum: 5 }
end