README

ruby - 3.2.3 rails - 7.1.3

1. rails new callback_example --database=mysql

2. cd callback_example

3. rails generate model Book title:string author:string

4. rails db:create rails db:migrate

5. app/modela/book.rb class Book < ApplicationRecord validates :title, presence: true

   after_initialize :set_defaults after_find :output_after_find

   before_validation :normalize_title, if: :title_changed? after_validation :print_validation_message

   after_commit :after_commit_callback, on: [:create, :update]

   before_save :print_save_message before_save :check_author_presence, unless: Proc.new { |book| book.author.present? } around_save :print_around_save_message after_save :print_saved_message

   before_create :print_create_message around_create :print_around_create_message after_create :print_created_message

   before_update :print_update_message around_update :print_around_update_message after_update :print_updated_message

   before_destroy :print_destroy_message around_destroy :print_around_destroy_message after_destroy :print_destroyed_message

   after_touch :notify_title_touched after_touch :notify_author_touched

   private

   def set_defaults puts "==============" puts "Book initialized with title: #{title}, author: #{author}" end

   def output_after_find puts "==============" puts "Book found with title: #{title}, author: #{author}" end

   def normalize_title self.title = title.capitalize if title.present? end

   def print_validation_message errors.add(:base, "Title can't be blank. Please add Title") if title.blank? end

   def print_save_message puts "==============" puts 'Book is being saved...' end

   def print_around_save_message yield puts "==============" puts 'Book saved successfully!' end

   def print_saved_message puts "==============" puts 'Book saved!' end

   def print_create_message puts "==============" puts 'Creating book...' end

   def print_around_create_message yield puts "==============" puts 'Book created!' end

   def print_created_message puts "==============" puts 'Book created!!' end

   def print_update_message puts "==============" puts 'Updating book...' end

   def print_around_update_message yield puts "==============" puts 'Book updated!' end

   def print_updated_message puts "==============" puts 'Book updated!!' end

   def print_destroy_message puts "==============" puts 'Destroying book...' end

   def print_around_destroy_message yield puts "==============" puts 'Book destroyed!' end

   def print_destroyed_message puts "==============" puts 'Book destroyed!!' end

   def notify_title_touched puts "==============" puts "Title '#{title}' has been touched." end

   def notify_author_touched puts "==============" puts "Author '#{author}' has been touched." end

   def check_author_presence self.author = "Unknown" unless self.author.present? end

   def after_commit_callback puts "==============" puts "Book '#{self.title}' by #{self.author} was committed successfully." end end

6. app/controllers/books_controller.rb class BooksController < ApplicationController before_action :set_book, except: [:index, :new, :create]

   def index @books = Book.all end

   def new @book = Book.new end

   def create @book = Book.new(book_params) if @book.save @book.touch redirect_to book_path(@book), notice: 'Book was successfully created.' else render :new end end

   def show end

   def edit end

   def update if @book.update(book_params) @book.touch redirect_to book_path(@book), notice: 'Book was successfully updated.' else render :edit end end

   def destroy @book.destroy redirect_to books_path, notice: 'Book was successfully destroyed.' end

   private

   def set_book @book = Book.find(params[:id]) end

   def book_params params.require(:book).permit(:title, :author) end end

7. app/views/books/index.html.erb

Listing Books

<%= link_to 'New Book', new_book_path %>

<% if @books.present? %>

<tbody>
  <% @books.each do |book| %>
    <tr>
      <td><%= book.id %></td>
      <td><%= book.title %></td>
      <td><%= book.author %></td>
      <td>
        <a href="<%= book_path(book) %>">Details</a> |
        <a href="<%= edit_book_path(book) %>">Edit</a> |
        <a href="<%= book_path(book) %>" data-turbo-method="delete" data-turbo-confirm="Are you sure?">Delete</a>
      </td>
    </tr>
  <% end %>
</tbody>

ID	Title	Author

<% end %>

8. app/views/books/new.html.erb

New Book

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

<%= link_to 'Back To List', books_path %>

9. app/views/books/edit.html.erb

Edit Book

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

Show | Back To List

10. app/views/books/_form.html.erb <%= form_with(model: book, local: true, data: { turbo: false }) do |form| %> <% if book.errors.any? %>

    <%= pluralize(book.errors.count, "error") %> prohibited this book from being saved:

    <ul>
      <% book.errors.full_messages.each do |message| %>
        <li><%= message %></li>
      <% end %>
    </ul>
    

    <% end %>
    <%= form.label :title %> <%= form.text_field :title %>
    
    
    <%= form.label :author %> <%= form.text_field :author %>
    
    
    <%= form.submit %>

<% end %>

11. app/views/books/ahow.html.erb

<%= @book.title %> Book

<%= "#{@book.title} by #{@book.author}" %>

<%= link_to 'Edit', edit_book_path(@book) %> | <%= link_to 'Back', books_path %>

12. config/routes.rb Rails.application.routes.draw do resources :books root 'books#index' end

13. rails s