「RubyでDDDやるならHanami」という噂の真相

old_book = OldBook.create(title: "hanami-ddd", author: "hanami") // ①

repository = OldBookRepository.new

repository.store(old_book) // ②

class OldBook < Hanami::Entity
end

class OldBookRepository < Hanami::Repository
end

// ユーザーがアプリからOldBookを追加するユースケース
class UsecaseFromUser // ①
  def initialize(repository:)
    @repository = repository
  end

  def call(title:, authoer:)
    if title.size >= 20 // ②
      raise ArgumentError, "titleは20文字までです。"
    end
    
    @repository.create(title: title, author: authoer)
  end
end

repository = OldBookRepository.new
UsecaseFromUser(repository: repository).call(title: "aaaaaaaaaaaaaaaaaaaaa", author: "hanami") 
=> 失敗！(想定通り！👏👏👏)

// 管理画面からOldBookを追加するユースケース
class UsecaseFromAdminPanel
  def initialize(repository:)
    @repository = repository
  end

  def call(title:, authoer:)
    # 忘れてた.... // ③
    # if title.size >= 20
    #   raise ArgumentError, "titleは20文字までです。"
    # end
    
    @repository.create(title: title, author: authoer)
  end
end

repository = OldBookRepository.new
UsecaseFromAdminPanel(repository: repository).call(title: "aaaaaaaaaaaaaaaaaaaaa", author: "hanami")
=> 成功！(想定外💣💣💣)

Hanami::Model.migration do
  change do
    create_table :new_books do
      primary_key :id

      column :title, String, null: false
      column :author, String, null: false
      column :created_at, DateTime, null: false
      column :updated_at, DateTime, null: false
    end
  end
end

class NewBook < Hanami::Entity
  MAX_TITLE_SIZE = 20
  def self.create(id:, title:, author:, created_at: Time.now, updated_at: Time.now) // ①
    if title.size >= MAX_TITLE_SIZE
      raise ArgumentError, "titleは#{MAX_TITLE_SIZE}文字までです。" // ②
    end

    self.new(
      id: id,
      title: title,
      author: author,
      created_at: created_at,
      updated_at: updated_at,
    )
  end
end

class NewBookRepository < Hanami::Repository
  def store(book) // ③
    new_books.insert(
      id: book.id,
      title: book.title,
      author: book.author,
      created_at: book.created_at,
      updated_at: book.updated_at,
    )
  end
end

new_book = NewBook.create(title: "hanami-ddd", author: "hanami")

repository = NewBookRepository.new

repository.store(new_book)