Add example of notifications

README.md

@@ -3,3 +3,4 @@
 * [Feedback form](feedback-form)
 * [Markdown preview](markdown-preview)
 * [Image upload with preview](image-upload-with-preview)
+* [Notification](notifications)

notifications/README.md

@@ -0,0 +1,184 @@
+# Notification
+
+In case we would like to to send notifications using multiple channels like Email
+and HipChat right after some business action (send feedback for example).
+
+The entry point is `SendFeedback` organizer which will organize interactors for:
+create feedback, send notification via Email, and send notification via HipChat.
+
+All notification will be pushed in the background using `ActiveJob`.
+
+```ruby
+# app/interactors/send_feedback.rb
+class SendFeedback
+  include Interactor::Organizer
+
+  organize CreateFeedback, NotifyUserViaEmail, NotifyUserViaHipchat
+end
+
+# app/interactors/notify_user_via_email.rb
+class NotifyUserViaEmail
+  include Interactor
+
+  delegate :feedback, to: :context
+  delegate :email, to: feedback.employee
+
+  def call
+    ApplicationMailer.feedback_notification(email, message.content_for(:email)).deliver_later
+  end
+
+  private
+
+  def message
+    FeedbackNotification.new(feedback)
+  end
+end
+
+# app/interactors/notify_user_via_hipchat.rb
+class NotifyUserViaHipchat
+  include Interactor
+
+  class Job < ActiveJob::Base
+    include Rollbar::ActiveJob
+
+    def perform(email, message)
+      HipchatApi.new.private_message(email, message)
+    end
+  end
+
+  delegate :feedback, to: :context
+  delegate :email, to: feedback.employee
+
+  def call
+    Job.perform_later(email, message.content_for(:hipchat))
+  end
+
+  private
+
+  def message
+    FeedbackNotification.new(feedback)
+  end
+end
+```
+
+Content for each notification is generated using `FeedbackNotification` class.
+
+Gem `render_anywhere` used in this example, but could be replaced with native Rails 5
+feature `ActionController::Renderer` later.
+
+```ruby
+# app/controllers/application_rendering_controller.rb
+class ApplicationRenderingController < RenderAnywhere::RenderingController
+  def default_url_options
+    { host: ENV.fetch("HOST") }
+  end
+end
+
+# app/models/fedback_notification.rb
+class FeedbackNotification
+  include RenderAnywhere
+
+  attr_reader :feedback, :rendering_controller
+  private :feedback, :rendering_controller
+
+  def initialize(feedback)
+    @feedback = feedback
+    @rendering_controller ||= ApplicationRenderingController.new
+  end
+
+  def content_for(type)
+    render(
+      template: template_for(type),
+      layout: false,
+      locals: locals
+    )
+  end
+
+  private
+
+  def template_for(type)
+    "feedback_notification/#{type}",
+  end
+
+  def locals
+    {
+      feedback: feedback.decorate
+    }
+  end
+end
+
+# app/views/feedback_notification/email.html.slim
+p
+  | You have new feedback from #{feedback.full_name_with_email}.
+
+  p
+    blockquote = feedback.text
+
+# app/views/feedback_notification/hipchat.html.slim
+p
+  | You have new feedback from #{feedback.full_name_with_email}.
+
+br
+
+  p
+    em = feedback.text
+```
+
+Here are examples of the wrapper for HipChat API and `ApplicationMailer`
+
+```ruby
+# app/models/hipchat_api.rb
+class HipchatApi
+  attr_reader :client
+  private :client
+
+  def initialize(client: build_client)
+    @client = client
+  end
+
+  def private_message(email, message, format = "html")
+    client.user(email).send(message, format)
+  rescue HipChat::UnknownUser => e
+    Rails.logger.error("HipChat: #{e.message}")
+  end
+
+  private
+
+  def build_client
+    HipChat::Client.new(ENV.fetch("HIPCHAT_TOKEN"), api_version: "v2")
+  end
+end
+
+# app/mailers/application_mailer.rb
+class ApplicationMailer < ActionMailer::Base
+  default from: ENV.fetch("MAILER_SENDER")
+
+  def feedback_notification(email, body)
+    mail(
+      body: body,
+      content_type: "text/html",
+      to: email,
+      subject: "You have new Feedback"
+    )
+  end
+end
+
+# config/application.rb
+module YourApp
+  class Application < Rails::Application
+    # Be sure to have the adapter's gem in your Gemfile
+    # and follow the adapter's specific installation
+    # and deployment instructions.
+    config.active_job.queue_adapter = :sidekiq
+  end
+end
+```
+
+```ruby
+# Gemfile
+gem "hipchat"
+gem "interactor"
+gem "render_anywhere"
+gem "sidekiq"
+```
+