Ruby on Rails - Bounded contexts via interface objects - Bounded Contexts example 1

application.rb

# config/application.rb
module MyApplication
  class Application < Rails::Application
    # ...
    # We need to tell Rails to include `app/bounded_contexts` in auto loader
    # This step is needed only in older Rails applications.
    # Any subdirs you put in `./app` should automatically get picked up as an autoload path in newer Rails
    config.autoload_paths << Rails.root.join('app', 'bounded_contexts')
    # ...
  end
end

classroom-lesson_creation_service.rb

# app/bounded_contexts/classroom/lesson_creation_service.rb
module Classroom
  module LessonCreationService
    extend self

    def call(students:, teacher:, title:)
      lesson = Lesson.create!(title: title, teacher: teacher)

      students.each do |student|
        lesson.students << student
        notify_student(student, lesson)
      end

      lesson
    end

    private

    def notify_student(student, lesson)
      Classroom::StudentMailer
        .invitation_to_lesson(lesson_id: lesson.id, student_id: student.id)
        .deliver_later
    end
  end
end

classroom-lesson_interface.rb

# app/bounded_contexts/classroom/lesson_interface.rb
module Classroom
  class LessonInterface
    attr_reader :lesson

    def initialize(lesson)
      @lesson = lesson
    end

    def upload_work(student:, file:)
      Classroom::WorkUploadService.call(student: student, lesson: lesson, file: file)
    end

    def publish
      lesson.published = true
      lesson.save!
    end

    def cross_boundary_example
      # some logic related to classroom bounded context
    end
  end
end

classroom-reprocess_work_thumbnail_job.rb

# app/bounded_contexts/classroom/reprocess_work_thumbnail_job.rb
module Classroom
  class ReprocessWorkThumbnailJob < ActiveJob::Base
    queue_as :classroom

    def perform(work_id:)
      work = Work.find_by!(id: work_id)

      # do something with the work
    end
  end
end

classroom-student_mailer.rb

# app/bounded_contexts/classroom/student_mailer.rb
class Classroom::StudentMailer < ApplicationMailer
  def invitation_to_lesson(lesson_id:, student_id:)
    @lesson = Lesson.find_by!(id: lesson_id)
    @student = Student.find_by!(id: student_id)

    mail(to: @student.email, subject: %{New lesson "#{@lesson.title}"})
  end
end

classroom-teacher_interface.rb

# app/bounded_contexts/classroom/teacher_interface.rb
module Classroom
  class TeacherInterface
    attr_reader :teacher

    def initialize(teacher)
      @teacher = teacher
    end

    def create_lesson(students:, title:)
      Lesson.transaction do
        Classroom::LessonCreationService.call(students: students, title: title, teacher: teacher)
      end
    end
  end
end

classroom-teacher_mailer.rb

# app/bounded_contexts/classroom/teacher_mailer.rb
module Classroom
  class TeacherMailer < ApplicationMailer
    def new_work_uploaded_to_lesson(work_id:, teacher_id:)
      @work = Work.find_by!(id: work_id)
      @teacher = Teacher.find_by!(id: teacher_id)

      mail(to: @teacher.email, subject: %{New work was added "#{@work.id}"})
    end
  end
end

classroom-work_upload_service.rb

# app/bounded_contexts/classroom/work_upload_service.rb
module Classroom
  module WorkUploadService
    extend self

    def call(student:, lesson:, file:)
      work = lesson.works.new(student: student)
      work.file = file
      work.save!

      notify_teacher(work, teacher)
      schedule_reprocess_work_thumbnail(work)
      work
    end

    private

    def notify_teacher(work, teacher)
      Classroom::TeacherMailer
        .new_work_uploaded_to_lesson(work_id: work.id, teacher_id: teacher.id)
        .deliver_later
    end

    def schedule_reprocess_work_thumbnail(work)
      Classroom::ReprocessWorkThumbnailJob.perform_later(work_id: work.id)
    end
  end
end

public_board-comment_posted_job.rb

# app/bounded_contexts/public_board/comment_posted_job.rb
module PublicBoard
  class CommentPostedJob < ActiveJob::Base
    queue_as :public_board

    def perform(comment_id:)
      comment = Comment.find_by!(id: comment_id)
      # do something with the comment
    end
  end
end

public_board-lesson_interface.rb

# app/bounded_contexts/public_board/lesson_interface.rb
module PublicBoard
  class LessonInterface
    attr_reader :lesson

    def initialize(lesson)
      @lesson = lesson
    end

    def mark_as_favorite(current_user:)
      # ... some logic
    end

    def cross
      # demonstration of how you can call other bounded context from this bounded context
      result = lesson.classroom.cross_boundary_example
      # ... you can use the result of different boundary in this boundary
    end
  end
end

public_board-student_mailer.rb

# app/bounded_contexts/public_board/student_mailer.rb
module PublicBoard
  class StudentMailer < ActiveJob::Base

    def new_comment_on_your_work(comment_id:)
      comment = Comment.find_by!(id: comment_id)
      # ...
    end
  end
end

public_board-work_interface.rb

# app/bounded_contexts/public_board/work_interface.rb
module PublicBoard
  class WorkInterface
    attr_reader :work

    def initialize(work)
      @work = work
    end

    def can_post_comment?(current_user:)
      work.lesson.published && current_user.is_a?(Student)
    end

    def post_comment(student:, content:)
      comment = @work.comments.create!(student: student, content: content)
      PublicBoard::CommentPostedJob.perform_later(comment_id: comment.id)
      PublicBoard::StudentMailer.new_comment_on_your_work(comment_id: comment.id).deliver_later
      comment
    end
  end
end

This is a GIST for Medium mirror article Ruby on Rails - Bounded contexts via interface object

https://medium.com/@tomas.valent/ruby-on-rails-bounded-contexts-via-interface-objects-4fd61738acaa

Original article: https://blog.eq8.eu/article/rails-bounded-contexts.html

Full list of Article GISTs:

• https://gist.github.com/equivalent/06f752d99b0d438759e3de22dbd2e9bd
• https://gist.github.com/equivalent/f9c5bfcea6e0afc5eb0f87510b26a21f
• https://gist.github.com/equivalent/37845308ca12097a11152aae63399caa
• https://gist.github.com/equivalent/5697f58cc1dd50f94ff094d8949d0c50