application_service.rb

application_service.rb

class ApplicationService
  include ActiveModel::Model

  def submit(params = {})
    params.each do |key, value|
      self.public_send("#{key}=", value)
    end

    self
  end

  def save
    raise NotImplementedError
  end
end

article.rb

class Article < ApplicationRecord
  # どんな状況でも絶対に満たしたい条件のバリデーションを書く
  validates :title, presence: true
  validates :body, length: {maximum: 1024}
end

create_article_service.rb

class CreateDraftArticleService < ApplicationService
  attr_accessor :title, :body
  
  # 下書き時は body が空でも良い
  validates :title, presence: true
  validates :body, presence: false, length: {maximum: 1024}
  
  def save
    Article.create(title: title, body: body)
  end
end

publish_article_service.rb

class PublishArticleService < ApplicationService
  attr_accessor :title, :body
  
  # 記事公開時は body 必須
  validates :title, presence: true
  validates :body, presence: true, length: {maximum: 1024}
  
  def initialize(article)
    @article = article
  end
  
  def save
    @article.update(title: title, body: body)
  end
end