Scaffolding

Scaffolding realizes CRUD(Create, Read, Update, Delete) operations easily.
Scaffolding has special, and migration file is also created
by scaffold command
This is not practical way but, it is very useful to learn 😉

• Create Scaffolding set
• Route
• Actions and Views

Create Scaffolding set

mode, controller, views, assets, etc…
Example)

rails g scaffold item title:string price:integer publish:string published:date

Use scaffold. Almost same as model definition.

Directory structure is following.

/application
  /app
     /models
	    item.rb			       : items table model class
	 /controllers
	 	items_controller.rb    : controller(CRUD)
	 /views
	    /items
		   index.html.erb	   : list
		   index.json.jbuilder : list(json)
		   edit.html.erb       : edit 
		   show.html.erb	   : show details
		   show.json.jbuilder  : show details(json)
		   new.html.erb		   : create
		   _form.html.erb      : create/edit common form
	 /assets
        /javascripts
           items.js.coffee	   : controller coffeescript
        /stylesheets
           items.css.scss	   : books controller SCSS
           scaffolds.css.scss      : SCSS for Scaffolding 	   
	/helpers
       items_helper.rb		   : books controller helper
  /db
       /migrate 
	       20141016145059_create_itemks.rb : migration file
  /test
       /models
	       item_test.rb				  : Model class test script
       /helpers
	       items_helper_test.rb       : View helper
       /controllers
	       items_controller_test.rb	  : Controller test script
       /fixtures
           items.yml		          : Fixture file

Next step, we will do migration.

Do migration

rake db:migrate

(Already exist rake db:migrate:reset)

You can see list http://localhost:3000/items

Delete

rails destroy scaffold item

Route

config/routes.rb

resources :items

Check routes using command

rake routes

Actions and Views

All actions are already implemented by Rails
app/controllers/items_controller.rb

List(index) action

def index
  @items = Item.all
end

View
index.json.jbuilder : JSON format
http://localhost:3000/items.json

items/index.html.erb
This is template

<h1>Listing items</h1>
<table>
  <thead>
    <tr>
	  <th>Title</th>
	  <th>Price</th>
	  <th>Publish</th>
	  <th>Published</th>
	  <th colspan="3"></th>
	</tr>
  </thead>
  <tbody>
    <% @items.each do |item| %>
	  <tr>
	    <td><%= item.title %></td>
	    <td><%= item.price %></td>
	    <td><%= item.publish %></td>
	    <td><%= item.published %></td>
	    <td><%= link_to 'Show', item %></td>
	    <td><%= link_to 'Edit', edit_book_path(item) %></td>
	    <td><%= link_to 'Destroy', item, method: :delete, data: { confirm: 'Are you sure?' }</td>
	  </tr>
	<% end %>
  </tbody>
</table>
<br>
<%= link_to 'New Item', new_item_path %>

Some links are generated automatically.

link_to

<%= link_to 'Show', item %>     # @item.id

The link is /items/1

ViewHelpers

Show

Show each item details
app/controllers/items_controller.rb

before_action :set_item, only: [:show, :edit, :update, :destroy]

def show
end

private
  def set_item
    @item = Item.find(params[:id])
  end

Retrieve data using id.
show.html.erb

<p id="notice"><%= notice %></p>

<p>
  <strong>Title:</strong>
  <%= @item.title %>
</p>

<p>
  <strong>Price:</strong>
  <%= @item.price %>
</p>

<p>
  <strong>Publish:</strong>
  <%= @item.publish %>
</p>

<p>
  <strong>Published:</strong>
  <%= @item.published %>
</p>

<%= link_to 'Edit', edit_item_path(@item) %> |
<%= link_to 'Back', items_path %>

notice tag : notice message place holder

new, create

Form
app/views/items/_form.html.erb

<%= form_for(@item) do |f| %>
  <% if @item.errors.any? %>
    <div id="error_explanation">
	  <h2><%= pluralize(@item.errors.count, "error") %> prohibited this book from being saved:</h2> 
	  <ul>
	    <% @item.errors.full_messages.each do |message| %>
		   <li><%= message %></li>
		<% end %>
	  </ul>  
	</div>
  <% end %>
  <div class="field">
    <%= f.label :title %><br>
	<%= f.text_field :title %>
  </div>
  <div class="field">
    <%= f.label :price %><br>
	<%= f.number_field :price %>
  </div>
  <div class="field">
    <%= f.label :publish %><br>
	<%= f.text_field :publish %>
  </div>
  <div class="field">
    <%= f.label :published %><br>
	<%= f.date_select :published %>
  </div>
  <div class="actions">
    <%= f.submit %>
  </div>
<% end %>

Actions
app/controllers/items_controller.rb

def new 
  @item = Item.new
end

def create
  @item = Item.new(item_params)
  
  respond_to do |format|
    if @item.save
	  format.html { redirect_to @item, notice: 'Item was successfully created' }
	  format.json { render :show, status: :created, location: @item }
	else
	  format.html { render :new }
	  format.json { render json: @item.errors, status: :unprocessable_entity }
	end
  end
end

Get post data

params.require(:item).permit(:title, :price, :publish)

edit/update

app/controllers/items_controller.rb

def edit
end

def update
  respond_to do |format|
     if @item.update(item_params)
	   format.html { redirect_to @item, notice: 'Item was successfully update.' }
	   format.json { render :show, status: :ok, location: @item }
	 else
	   format.html { render :edit }
	   format.json { render json: @item.errors, status: :unprocessable_entity }
	 end
  end
end

Views
app/views/items/edit.html.erb

<h1>Editing item</h1>
<%= render 'form' %>
<%= link_to 'Show', @item %>
<%= link_to 'Back', items_path %>

destroy

app/controllers/items_controller.rb

def destroy
  @item.destroy
  
  respond_to do |format|
     format.html { redirect_to items_url, notice: 'Item was successfully destroyed.' }
	 format.json { head: no_content }
  end
end