ソフトウェアエンジニアの技術ブログ：Software engineer tech blog

### relation(belongs:to)
$ rails g model Comment body:string post:references
$ rails db:migrate

model
app/models.comment.rb

class Comment < ApplicationRecord
  belongs_to :post
  validates :body, prensence: true
end

post modelにもcommentと紐づいていることを書く

class Post < ApplicationRecord
	has_many :comments
	validates :title, presence: true, length: {minimum: 3, message: 'too short to post!'}
	validates :body, presence: true
end

post.comments と書くことができる様になる

routes.rb

  resources :posts do
  	resources :comments
  end

$ rails routes
Prefix Verb URI Pattern Controller#Action
post_comments GET /posts/:post_id/comments(.:format) comments#index
POST /posts/:post_id/comments(.:format) comments#create
new_post_comment GET /posts/:post_id/comments/new(.:format) comments#new
edit_post_comment GET /posts/:post_id/comments/:id/edit(.:format) comments#edit
post_comment GET /posts/:post_id/comments/:id(.:format) comments#show
PATCH /posts/:post_id/comments/:id(.:format) comments#update
PUT /posts/:post_id/comments/:id(.:format) comments#update
DELETE /posts/:post_id/comments/:id(.:format) comments#destroy
posts GET /posts(.:format) posts#index
POST /posts(.:format) posts#create
new_post GET /posts/new(.:format) posts#new
edit_post GET /posts/:id/edit(.:format) posts#edit
post GET /posts/:id(.:format) posts#show
PATCH /posts/:id(.:format) posts#update
PUT /posts/:id(.:format) posts#update
DELETE /posts/:id(.:format) posts#destroy
root GET / posts#index

$ rails g controller Comments

show.html.erb

<h3>Comments</h3>
<%= form_for ([@post, @post.comments.build]) do |f| %>
<p>
	<%= f.text_field:body %>
</p>
<p>
	<%= f.submit %>
</p>
<% end %>

comments_controller.rb

	def create
		# render plain: params[:post].inspect
		@post = Post.find(params[:post_id])
		@post.comments.create(comment_params)
		redirect_to post_path(@post)
	end

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

posts_controller.rb
L 変更なし

	def show
		@post = Post.find(params[:id])
	end

show.html.erb

<ul>
	<% @post.comments.each do |comment| %>
	<li>
		<%= comment.body %>
		<%= link_to '[x]', 
			post_comment_path(@post, comment), 
			method: :delete, 
			class: 'command',
			data: { confirm: 'Sure ?'} %>		
	</li>
	<% end %>
</ul>

controller

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

route

Rails.application.routes.draw do
  # For details on the DSL available within this file, see http://guides.rubyonrails.org/routing.html
  resources :posts do
  	resources :comments, only: [:create, :destroy]
  end

  root 'posts#index'
end

記事を削除した時にコメントも削除する
model

class Post < ApplicationRecord
	has_many :comments, dependent: :destroy
	validates :title, presence: true, length: {minimum: 3, message: 'too short to post!'}
	validates :body, presence: true
end

なるほど、オリジナルで作らんとダメやな

viewでヘルパーを使用
index.html.erb

		<% @posts.each do |post| %>
		<li>
			<%= link_to post.title, post_path(post) %>				
		</li>
		<% end %>

posts_controller.rb

	def show
		@post = Post.find(params[:id])
	end

show.html.erb

<h2><%= @post.title %></h2>
<p><%= @post.body %></p>

app/assets/images/logo.png
link_toでリンクを指定し、root_pathでリンク先を指定する

  	<div class="container">
  		<h1><%= link_to image_tag('logo.png', class: 'logo'), root_path %></h1>
    <%= yield %>
	</div>

css

.logo {
	width: 200px;
	height: 50px;
}

リンクを作成する

	<h2>
		<%= link_to 'Add New', new_post_path, class: 'header-menu' %>
		My Posts
	</h2>

css

.header-menu {
	font-size: 12px;
	font-weight: normal;
	float: right;
}

controller

	def new
	end

	def create
	end

new.html.erb

<h2>Add New Post</h2>
<%= form_for :post, url:posts_path do |f| %>
<p>
	<%= f.text_field:title, placeholder: 'enter title' %>
</p>
<p>
	<%= f.text_area:body, placeholder: 'enter body text' %>
</p>
<p>
	<%= f.submit %>
</p>
<% end %>

css

input[type="text"], textarea {
	box-sizing: border-box;
	width: 400px;
	padding: 5px;
}

textarea {
	height: 160px;
}

posts_controller.rb

	def create
		render plain: params[:post].inspect
	end

“aa”, “body”=>”bb”} permitted: false>

	def create
		# render plain: params[:post].inspect
		@post = Post.new(params[:post])
		@post.save
		redirect_to posts_path
	end

private methodで書く

	def create
		# render plain: params[:post].inspect
		@post = Post.new(post_params)
		@post.save
		redirect_to posts_path
	end

	private
		def post_params
			params.require(:post).permit(:title, :body)
		end

バリデーション
app/models/post.rb

class Post < ApplicationRecord
	validates :title, presence: true, length: {minimum: 3, message: 'too short to post!'}
	validates :body, presence: true
end

controller

	def create
		# render plain: params[:post].inspect
		@post = Post.new(post_params)
		if @post.save
			redirect_to posts_path
		else
			render 'new'
		end
	end

view

<p>
	<%= f.text_field:title, placeholder: 'enter title' %>
	<% if @post.errors.messages[:title].any? %>
	<span class="error"><%= @post.errors.messages[:title][0] %></span>
	<% end %>
</p>
<p>
	<%= f.text_area:body, placeholder: 'enter body text' %>
	<% if @post.errors.messages[:body].any? %>
	<span class="error"><%= @post.errors.messages[:body][0] %></span>
	<% end %>
</p>

### edit
index.html.erb

			<%= link_to post.title, post_path(post) %>	
			<%= link_to '[Edit]', edit_post_path(post), class: 'command' %>		

controller

	def edit 
		@post = Post.find(params[:id])
	end

edit.html.erb
L newとほぼ同じ

<h2>Edit Post</h2>
<%= form_for @post, url:post_path(@post) do |f| %>
<p>
	<%= f.text_field:title, placeholder: 'enter title' %>
	<% if @post.errors.messages[:title].any? %>
	<span class="error"><%= @post.errors.messages[:title][0] %></span>
	<% end %>
</p>
<p>
	<%= f.text_area:body, placeholder: 'enter body text' %>
	<% if @post.errors.messages[:body].any? %>
	<span class="error"><%= @post.errors.messages[:body][0] %></span>
	<% end %>
</p>
<p>
	<%= f.submit %>
</p>
<% end %>

controller

	def update
		@post = Post.find(params[:id])
		if @post.update(post_params)
			redirect_to posts_path
		else
			render 'edit'
		end
	end

改行を適切なタグに直す

<h2><%= @post.title %></h2>
<p><%= simple_format @post.body %></p>

### partialで共通部品を作る
partialはアンダーバー(_)から始める
views/posts/_form.html.erb

<%= form_for @post do |f| %>
<p>
	<%= f.text_field:title, placeholder: 'enter title' %>
	<% if @post.errors.messages[:title].any? %>
	<span class="error"><%= @post.errors.messages[:title][0] %></span>
	<% end %>
</p>
<p>
	<%= f.text_area:body, placeholder: 'enter body text' %>
	<% if @post.errors.messages[:body].any? %>
	<span class="error"><%= @post.errors.messages[:body][0] %></span>
	<% end %>
</p>
<p>
	<%= f.submit %>
</p>
<% end %>

edit.html.erb
L partialの名前をアンダーバー抜きで書く

<h2>Edit Post</h2>
<%= render 'form' %>

new.html.erb

<h2>Add New Post</h2>
<%= render 'form' %>

### delete

		<li>
			<%= link_to post.title, post_path(post) %>	
			<%= link_to '[Edit]', edit_post_path(post), class: 'command' %>
			<%= link_to '[x]', 
			post_path(post), 
			method: :delete, 
			class: 'command',
			data: { confirm: 'Sure ?'} %>	
		</li>

controller

	def destroy
		@post = Post.find(params[:id])
		@post.destroy
		redirect_to posts_path
	end