【Rails】超便利コマンドscaffoldの使い方を完全理解｜何が起こっているかを徹底解説

rails g scaffold モデル名 <カラム名1:型1> <カラム名2:型2>,,,

# rails g scaffold user name:string, age:integer
Running via Spring preloader in process 308
      invoke  active_record
   identical    db/migrate/20210729000816_create_users.rb
   identical    app/models/user.rb
      invoke    test_unit
   identical      test/models/user_test.rb
   identical      test/fixtures/users.yml
      invoke  resource_route
       route    resources :users
      invoke  scaffold_controller
   identical    app/controllers/users_controller.rb
      invoke    erb
       exist      app/views/users
   identical      app/views/users/index.html.erb
   identical      app/views/users/edit.html.erb
   identical      app/views/users/show.html.erb
   identical      app/views/users/new.html.erb
   identical      app/views/users/_form.html.erb
      invoke    resource_route
      invoke    test_unit
   identical      test/controllers/users_controller_test.rb
   identical      test/system/users_test.rb
      invoke    helper
   identical      app/helpers/users_helper.rb
      invoke      test_unit
      invoke    jbuilder
      create      app/views/users/index.json.jbuilder
      create      app/views/users/show.json.jbuilder
      create      app/views/users/_user.json.jbuilder
      invoke  assets
      invoke    scss
       force      app/assets/stylesheets/users.scss
      invoke  scss
      create    app/assets/stylesheets/scaffolds.scss

class CreateUsers < ActiveRecord::Migration[6.1]
  def change
    create_table :users do |t|
      t.string, :name
      t.integer :age

      t.timestamps
    end
  end
end

class User < ApplicationRecord
end

class UsersController < ApplicationController
  before_action :set_user, only: %i[ show edit update destroy ]

  # GET /users or /users.json
  def index
    @users = User.all
  end

  # GET /users/1 or /users/1.json
  def show
  end

  # GET /users/new
  def new
    @user = User.new
  end

  # GET /users/1/edit
  def edit
  end

  # POST /users or /users.json
  def create
    @user = User.new(user_params)

    respond_to do |format|
      if @user.save
        format.html { redirect_to @user, notice: "User was successfully created." }
        format.json { render :show, status: :created, location: @user }
      else
        format.html { render :new, status: :unprocessable_entity }
        format.json { render json: @user.errors, status: :unprocessable_entity }
      end
    end
  end

  # PATCH/PUT /users/1 or /users/1.json
  def update
    respond_to do |format|
      if @user.update(user_params)
        format.html { redirect_to @user, notice: "User was successfully updated." }
        format.json { render :show, status: :ok, location: @user }
      else
        format.html { render :edit, status: :unprocessable_entity }
        format.json { render json: @user.errors, status: :unprocessable_entity }
      end
    end
  end

  # DELETE /users/1 or /users/1.json
  def destroy
    @user.destroy
    respond_to do |format|
      format.html { redirect_to users_url, notice: "User was successfully destroyed." }
      format.json { head :no_content }
    end
  end

  private
    # Use callbacks to share common setup or constraints between actions.
    def set_user
      @user = User.find(params[:id])
    end

    # Only allow a list of trusted parameters through.
    def user_params
      params.require(:user).permit(:name, :age)
    end
end

#基本形
before_action :メソッド名


#メソッドを複数指定
before_action :メソッド名1, :メソッド名2, :メソッド名3,,, 

#アクションの指定
before_action :メソッド名, only: :アクション名   #1つの場合
before_action :メソッド名, only: [:アクション名1, :アクション名2,,,]　#複数の場合


#指定したアクションのみ適用を除外
before_action :メソッド名, except: :アクション名   #1つの場合
before_action :メソッド名, except: [:アクション名1, :アクション名2,,,]  #複数の場合

before_action :set_user, only: %i[ show edit update destroy ]

  private
    # Use callbacks to share common setup or constraints between actions.
    def set_user
      @user = User.find(params[:id])
    end
    (省略) 

  private
   # Only allow a list of trusted parameters through.
    def user_params
      params.require(:user).permit(:name, :age)
    end

"action" : "create",
"user": 
  {
    "name": "test",
    "age": 24,
    "roll": 1
  }
"controller" : "users"
}

"user": 
  {
    "name": "test",
    "age": 24,
    "roll": 1
  }

{  
  "name": "test",
  "age": 24
}

  def create
    @user = User.new(user_params)
    @user.save
  end

  # POST /users or /users.json
  def create
    @user = User.new(user_params)

    respond_to do |format|
      if @user.save
        format.html { redirect_to @user, notice: "User was successfully created." }
        format.json { render :show, status: :created, location: @user }
      else
        format.html { render :new, status: :unprocessable_entity }
        format.json { render json: @user.errors, status: :unprocessable_entity }
      end
    end
  end

format.html { redirect_to @user, notice: "User was successfully created." }
format.json { render :show, status: :created, location: @user }

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

<h1>Users</h1>

<table>
  <thead>
    <tr>
      <th>Name</th>
      <th>Age</th>
      <th colspan="3"></th>
    </tr>
  </thead>

  <tbody>
    <% @users.each do |user| %>
      <tr>
        <td><%= user.name %></td>
        <td><%= user.age %></td>
        <td><%= link_to 'Show', user %></td>
        <td><%= link_to 'Edit', edit_user_path(user) %></td>
        <td><%= link_to 'Destroy', user, method: :delete, data: { confirm: 'Are you sure?' } %></td>
      </tr>
    <% end %>
  </tbody>
</table>

<br>

<%= link_to 'New User', new_user_path %>

<h1>Editing User</h1>

<%= render 'form', user: @user %>

<%= link_to 'Show', @user %> |
<%= link_to 'Back', users_path %>

<%= form_with(model: user) do |form| %>
  <% if user.errors.any? %>
    <div id="error_explanation">
      <h2><%= pluralize(user.errors.count, "error") %> prohibited this user from being saved:</h2>

      <ul>
        <% user.errors.each do |error| %>
          <li><%= error.full_message %></li>
        <% end %>
      </ul>
    </div>
  <% end %>

  <div class="field">
    <%= form.label :name %>
    <%= form.text_field :name %>
  </div>

  <div class="field">
    <%= form.label :age %>
    <%= form.number_field :age %>
  </div>

  <div class="actions">
    <%= form.submit %>
  </div>
<% end %>

<h1>New User</h1>

<%= render 'form', user: @user %>

<%= link_to 'Back', users_path %>

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

<p>
  <strong>Name:</strong>
  <%= @user.name %>
</p>

<p>
  <strong>Age:</strong>
  <%= @user.age %>
</p>

<%= link_to 'Edit', edit_user_path(@user) %> |
<%= link_to 'Back', users_path %>

format.html { redirect_to @user, notice: "User was successfully created." }

<%= render 'form', user: @user %>

<%= form_with(model: user) do |form| %>
　
  <%# ーーエラー発生時の処理ーー %>
  <% if user.errors.any? %>
    <div id="error_explanation">
      <h2><%= pluralize(user.errors.count, "error") %> prohibited this user from being saved:</h2>

      <ul>
        <% user.errors.each do |error| %>
          <li><%= error.full_message %></li>
        <% end %>
      </ul>
    </div>
  <% end %>

  <%# ーー入力フォームーー %>
  <div class="field">
    <%= form.label :name %>
    <%= form.text_field :name %>
  </div>

  <div class="field">
    <%= form.label :age %>
    <%= form.number_field :age %>
  </div>

  <div class="actions">
    <%= form.submit %>
  </div>
<% end %>

module UsersHelper
end

// Place all the styles related to the users controller here.
// They will automatically be included in application.css.
// You can use Sass (SCSS) here: https://sass-lang.com/

body {
  background-color: #fff;
  color: #333;
  margin: 33px; }

body, p, ol, ul, td {
  font-family: verdana, arial, helvetica, sans-serif;
  font-size: 13px;
  line-height: 18px; }

pre {
  background-color: #eee;
  padding: 10px;
  font-size: 11px; }

a {
  color: #000; }

a:visited {
  color: #666; }

a:hover {
  color: #fff;
  background-color: #000; }

th {
  padding-bottom: 5px; }

td {
  padding: 0 5px 7px; }

div.field,
div.actions {
  margin-bottom: 10px; }

#notice {
  color: green; }

.field_with_errors {
  padding: 2px;
  background-color: red;
  display: table; }

#error_explanation {
  width: 450px;
  border: 2px solid red;
  padding: 7px 7px 0;
  margin-bottom: 20px;
  background-color: #f0f0f0; }

#error_explanation h2 {
  text-align: left;
  font-weight: bold;
  padding: 5px 5px 5px 15px;
  font-size: 12px;
  margin: -7px -7px 0;
  background-color: #c00;
  color: #fff; }

#error_explanation ul li {
  font-size: 12px;
  list-style: square; }

label {
  display: block; }

require_relative "boot"

require "rails/all"

# Require the gems listed in Gemfile, including any gems
# you've limited to :test, :development, or :production.
Bundler.require(*Rails.groups)

module RailsVue
  class Application < Rails::Application
    (省略)

     #scaffolds.scssを生成しない
    config.generators do |g|
      g.scaffold_stylesheet false
    end
  end
end

require_relative "boot"

require "rails/all"

# Require the gems listed in Gemfile, including any gems
# you've limited to :test, :development, or :production.
Bundler.require(*Rails.groups)

module RailsVue
  class Application < Rails::Application
    (省略)

     #scaffoldでスタイルシートを生成しない
    config.generators do |g|
      g.stylesheet false
    end
  end
end

json.array! @users, partial: "users/user", as: :user

json.extract! user, :id, :name, :age, :created_at, :updated_at
json.url user_url(user, format: :json)

json.partial! "users/user", user: @user

[{"id":1,"name":"test1","age":24,"created_at":"2021-07-29T04:38:52.761Z","updated_at":"2021-07-29T04:38:52.761Z","url":"http://localhost:3001/users/1.json"},{"id":3,"name":"test2","age":25,"created_at":"2021-07-30T23:18:28.177Z","updated_at":"2021-07-30T23:18:28.177Z","url":"http://localhost:3001/users/3.json"},{"id":4,"name":"test3","age":28,"created_at":"2021-07-30T23:19:35.242Z","updated_at":"2021-07-30T23:19:35.242Z","url":"http://localhost:3001/users/4.json"},{"id":5,"name":"test4","age":30,"created_at":"2021-07-30T23:19:44.976Z","updated_at":"2021-07-30T23:19:44.976Z","url":"http://localhost:3001/users/5.json"},{"id":6,"name":"test5","age":32,"created_at":"2021-07-30T23:19:54.558Z","updated_at":"2021-07-30T23:19:54.558Z","url":"http://localhost:3001/users/6.json"}]

{"id":1,"name":"test1","age":24,"created_at":"2021-07-29T04:38:52.761Z","updated_at":"2021-07-29T04:38:52.761Z","url":"http://localhost:3001/users/1.json"}

Rails.application.routes.draw do
  resources :users
end

# rails routes
   Prefix Verb   URI Pattern　　              Controller#Action
new_user  GET    /users/new(.:format)         users#new
edit_user GET    /users/edit(.:format)        users#edit
users     GET    /users/(.:format)            users#show
          PATCH  /users/(.:format)            users#update
          PUT    /users/(.:format)            users#update
          DELETE /users/(.:format)            users#destroy
          POST   /users(.:format)             users#create

rails destroy scaffold <モデル名>

# rails g scaffold project name:string age:integer price:integer
Running via Spring preloader in process 63
      invoke  active_record
      create    db/migrate/20210731095320_create_projects.rb
      create    app/models/project.rb
      invoke    test_unit
      create      test/models/project_test.rb
      create      test/fixtures/projects.yml
      invoke  resource_route
       route    resources :projects
      invoke  scaffold_controller
      create    app/controllers/projects_controller.rb
      invoke    erb
      create      app/views/projects
      create      app/views/projects/index.html.erb
      create      app/views/projects/edit.html.erb
      create      app/views/projects/show.html.erb
      create      app/views/projects/new.html.erb
      create      app/views/projects/_form.html.erb
      invoke    resource_route
      invoke    test_unit
      create      test/controllers/projects_controller_test.rb
      create      test/system/projects_test.rb
      invoke    helper
      create      app/helpers/projects_helper.rb
      invoke      test_unit
      invoke    jbuilder
      create      app/views/projects/index.json.jbuilder
      create      app/views/projects/show.json.jbuilder
      create      app/views/projects/_project.json.jbuilder
      invoke  assets
      invoke    scss
      create      app/assets/stylesheets/projects.scss
      invoke  scss
   identical    app/assets/stylesheets/scaffolds.scss

# rails destroy scaffold project name:string age:integer price:integer
Running via Spring preloader in process 76
      invoke  active_record
      remove    db/migrate/20210731095320_create_projects.rb
      remove    app/models/project.rb
      invoke    test_unit
      remove      test/models/project_test.rb
      remove      test/fixtures/projects.yml
      invoke  resource_route
       route    resources :projects
      invoke  scaffold_controller
      remove    app/controllers/projects_controller.rb
      invoke    erb
      remove      app/views/projects
      remove      app/views/projects/index.html.erb
      remove      app/views/projects/edit.html.erb
      remove      app/views/projects/show.html.erb
      remove      app/views/projects/new.html.erb
      remove      app/views/projects/_form.html.erb
      invoke    resource_route
      invoke    test_unit
      remove      test/controllers/projects_controller_test.rb
      remove      test/system/projects_test.rb
      invoke    helper
      remove      app/helpers/projects_helper.rb
      invoke      test_unit
      invoke    jbuilder
      remove      app/views/projects
      remove      app/views/projects/index.json.jbuilder
      remove      app/views/projects/show.json.jbuilder
      remove      app/views/projects/_project.json.jbuilder
      invoke  assets
      invoke    scss
      remove      app/assets/stylesheets/projects.scss
      invoke  scss