Hanami Repository Bulk Update Update multiple database records at once

Hanami Repository Bulk Update

Imagine that your team is tasked to implement a feature that enables a human to review and publish a list of books. Most of the work has already been done, what remains is to update the published_at attribute of the subset of books that were reviewed. To that end you’ll implement a publish method on the BookRepository that takes the list of reviewed books and updates them.

# lib/bookshelf/repositories/book_repository.rb
# frozen_string_literal: true

class BookRepository < Hanami::Repository
  def publish(reviewed_books)
    books
      .where(id: reviewed_books.map(&:id))
      .update(published_at: Time.now)
  end
end

The feature is a success and your users are happy. It turns out that there are a lot more bulk operations that users would like to be able to do. For now we want to enable users to set discounts for books in bulk. Again the UI is already updated and all we have left to do is implement this in our repository.

# lib/bookshelf/repositories/book_repository.rb
# frozen_string_literal: true

class BookRepository < Hanami::Repository
  def publish(reviewed_books)
    update_all(reviewed_books, published_at: Time.now)
  end
  
  def discount(books_on_sale, reduction_rate)
    # we validate the reduction rate at the controller level, it may even be a
    # value object
    update_all(books_on_sale, discount: reduction_rate.to_f)
  end

  private

  def update_all(books_to_update, **attribute_value_pairs)
    books
      .where(id: books_to_update.map(&:id))
      .update(**attribute_value_pairs)
  end
end

While it is tempting to just implement the generic update_all method publicly and use it outside of the repository this flexibility would come at a cost. The knowledge of what publishing books or granting discounts means would potentially be spread across our code base.

Instead we define less flexible but intention revealing methods that naturally attract behaviour pertaining to their responsibility.