Ruby on RailsでCRUDアプリケーションを構築する：ステップバイステップガイド

Let’s take a deep dive into building a fully functional CRUD (Create, Read, Update, Delete) application using Ruby on Rails. We will walk through each step of the process, providing technical examples and explanations to help you understand the concepts and implementation details. By the end of this guide, you will have a solid foundation in developing CRUD applications with Ruby on Rails.

Step 1: Install Ruby on Rails
Make sure you have Ruby and Rails installed on your system. You can install Rails using the following command:

gem install rails

Step 2: Create a New Rails Application

Create a new Rails application using the following command:

rails new crud_app
cd crud_app

Step 3: Generate a Model

Generate a model for the application. In this example, we’ll create a “Task” model with a title and description.

rails generate model Task title:string description:text
rake db:migrate

Step 4: Generate a Controller
Generate a controller to handle the CRUD operations for the Task model.

rails generate controller Tasks

Step 5: Define Routes
Open the config/routes.rb file and define the routes for the Tasks controller:

# config/routes.rb
Rails.application.routes.draw do

resources :tasks
root 'tasks#index'
end

Step 6: Implement Controller Actions

Open the app/controllers/tasks_controller.rb file and implement the CRUD actions:
# app/controllers/tasks_controller.rb
class TasksController < ApplicationController
before_action :set_task, only: [:show, :edit, :update, :destroy]
def index
@tasks = Task.all
end
def show
end
def new
@task = Task.new
end

def create
@task = Task.new(task_params)
if @task.save
redirect_to @task, notice: 'Task was successfully created.'
else
render :new
end
end
def edit
end

def update
if @task.update(task_params)
redirect_to @task, notice: 'Task was successfully updated.'
else
render :edit
end
end
def destroy
@task.destroy
redirect_to tasks_url, notice: 'Task was successfully destroyed.'
end
private
def set_task
@task = Task.find(params[:id])
end
def task_params
params.require(:task).permit(:title, :description)
end
end

Step 7: Create Views
Create views for the Tasks controller. You can use the default Rails scaffold views or customize them based on your needs.

Step 8: Run the Application
Start the Rails server and navigate to http://localhost:3000 to see your CRUD application in action.

rails server

That’s it! You’ve now created a simple CRUD application with Ruby on Rails. You can further customize and enhance it based on your requirements.

結論：

CRUD operations, which encompass creating, reading, updating, and deleting data, are fundamental components of nearly every web application. By completing this step-by-step guide, you have acquired a comprehensive understanding of building a CRUD application with Ruby on Rails. Armed with these skills and knowledge, you’re now well-equipped to embark on your own Ruby on Rails development projects with confidence. Happy coding!