TheRusskiy · May 25, 2021 09:28 · May 25, 2021 · May 25, 2021 · May 25, 2021 · May 25, 2021
diff --git a/application_mailer.rb b/application_mailer.rb
@@ -3,11 +3,15 @@ def new_blog_post(blog_post, subscriber)
     # by calling "store_message" we are saying that this
     # emails need to be saved in our database
     # for further tracking
-    store_message(email_name: 'new_blog_post', entity: blog_post)
+    store_message(
+      email_name: 'new_blog_post',
+      entity: blog_post,
+      user: subscriber
+    )
 
     mail(
       to: subscriber.email,
-      subject: "New Post: #{blog_post.title}",      
+      subject: "New Post: #{blog_post.title}",
       # this param is required if you want Postmark to add a tracking pixel
       # and send you status updates
       track_opens: 'true'
@@ -18,9 +22,11 @@ def new_blog_post(blog_post, subscriber)
 
   # email_name - some name we can later use for statistics
   # entity - any ActiveRecord model we want to associate the email with
-  def store_message(email_name:, entity:)
+  # user - user this email is sent to
+  def store_message(email_name:, entity:, user: nil)
     self.metadata['email_name'] = email_name.to_s.truncate(80)
     self.metadata['entity_id'] = entity.id
     self.metadata['entity_type'] = entity.class.name
+    self.metadata['user_id'] = user.id if user
   end
-end
+end
diff --git a/migration.rb b/migration.rb
@@ -4,6 +4,7 @@ def change
       t.text :email_name, null: false
       t.text :message_id
       t.references :entity, polymorphic: true, index: true
+      t.references :user, foreign_key: true, null: true, index: true
       t.integer :status, default: 0, null: false
       t.datetime :opened_at
       t.text :error

diff --git a/postmark_observer.rb b/postmark_observer.rb
@@ -15,6 +15,7 @@ def self.delivered_email(m)
       message_id: m.message_id,
       entity_id: m.metadata['entity_id'],
       entity_type: m.metadata['entity_type'],
+      user_id: m.metadata['user_id'],
       subject: m.subject
     )
   end

diff --git a/sent_email.rb b/sent_email.rb
@@ -1,5 +1,6 @@
 class SentEmail < ApplicationRecord
   belongs_to :entity, polymorphic: true
+  belongs_to :user, optional: true
   enum status: { sent: 0, opened: 1, failed: 2 }
   validates_presence_of :email_name, :status
   validates_presence_of :message_id, unless: :failed?

diff --git a/application_mailer.rb b/application_mailer.rb
@@ -7,7 +7,9 @@ def new_blog_post(blog_post, subscriber)
 
     mail(
       to: subscriber.email,
-      subject: "New Post: #{blog_post.title}",
+      subject: "New Post: #{blog_post.title}",      
+      # this param is required if you want Postmark to add a tracking pixel
+      # and send you status updates
       track_opens: 'true'
     )
   end

diff --git a/postmark_observer.rb b/postmark_observer.rb
@@ -19,3 +19,5 @@ def self.delivered_email(m)
     )
   end
 end
+
+ActionMailer::Base.register_observer(PostmarkMailObserver)
diff --git a/application_mailer.rb b/application_mailer.rb
@@ -0,0 +1,24 @@
+class ApplicationMailer < ActionMailer::Base
+  def new_blog_post(blog_post, subscriber)
+    # by calling "store_message" we are saying that this
+    # emails need to be saved in our database
+    # for further tracking
+    store_message(email_name: 'new_blog_post', entity: blog_post)
+
+    mail(
+      to: subscriber.email,
+      subject: "New Post: #{blog_post.title}",
+      track_opens: 'true'
+    )
+  end
+
+  protected
+
+  # email_name - some name we can later use for statistics
+  # entity - any ActiveRecord model we want to associate the email with
+  def store_message(email_name:, entity:)
+    self.metadata['email_name'] = email_name.to_s.truncate(80)
+    self.metadata['entity_id'] = entity.id
+    self.metadata['entity_type'] = entity.class.name
+  end
+end
diff --git a/email_bounced_service.rb b/email_bounced_service.rb
@@ -0,0 +1,9 @@
+class EmailBouncedService
+  def self.call(message_id:, error_message:)
+    sent_email = SentEmail.find_by_message_id(message_id)
+
+    return unless sent_email
+
+    sent_email.update!(error: error_message, status: 'failed')
+  end
+end
diff --git a/email_opened_service.rb b/email_opened_service.rb
@@ -0,0 +1,10 @@
+class EmailOpenedService
+  def self.call(message_id:, first_open:, opened_at:)
+    return unless first_open
+
+    sent_email = SentEmail.find_by_message_id(message_id)
+    return unless sent_email
+
+    sent_email.update!(error: nil, status: 'opened', opened_at: opened_at)
+  end
+end
diff --git a/migration.rb b/migration.rb
@@ -0,0 +1,17 @@
+class CreateSentEmails < ActiveRecord::Migration[6.1]
+  def change
+    create_table :sent_emails do |t|
+      t.text :email_name, null: false
+      t.text :message_id
+      t.references :entity, polymorphic: true, index: true
+      t.integer :status, default: 0, null: false
+      t.datetime :opened_at
+      t.text :error
+      t.timestamps
+
+      t.index :email_name
+      t.index :entity_id
+      t.index :message_id
+    end
+  end
+end
diff --git a/postmark_controller.rb b/postmark_controller.rb
@@ -0,0 +1,26 @@
+class PostmarkController < ActionController::Base
+  skip_before_action :verify_authenticity_token
+  # we are going to secure this webhook endpoint by using basic auth,
+  # when defining your webhook on Postmark you should set it as
+  # https://<username>:<password>@example.com/postmark_opened
+  # https://<username>:<password>@example.com/postmark_bounced
+  # TODO: use real credentials for basic auth
+  http_basic_authenticate_with name: "SECRET_NAME", password: "SECRET_PASSWORD"
+
+  def email_opened
+    EmailOpenedService.call(
+      message_id: params[:MessageID],
+      first_open: params[:FirstOpen],
+      opened_at: params[:ReceivedAt]
+    )
+    render json: { status: 201 }
+  end
+
+  def email_bounced
+    EmailBouncedService.call(
+      message_id: params[:MessageID],
+      error_message: params[:Description]
+    )
+    render json: { status: 201 }
+  end
+end
diff --git a/postmark_observer.rb b/postmark_observer.rb
@@ -0,0 +1,21 @@
+# place this file in config/initializers
+
+class PostmarkMailObserver
+  def self.delivered_email(m)
+    # only create a record if API has accepted the message
+    return unless m.delivered?
+
+    # as a part of API we are going to assume that
+    # an email should be saved if "email_name" is set
+    return unless m.metadata['email_name'].present?
+
+    SentEmail.create(
+      email_name: m.metadata['email_name'],
+      status: 'sent',
+      message_id: m.message_id,
+      entity_id: m.metadata['entity_id'],
+      entity_type: m.metadata['entity_type'],
+      subject: m.subject
+    )
+  end
+end
diff --git a/routes.rb b/routes.rb
@@ -0,0 +1,4 @@
+Rails.application.routes.draw do
+  post 'postmark_opened', to: 'postmark#email_opened'
+  post 'postmark_bounced', to: 'postmark#email_bounced'
+end
diff --git a/sent_email.rb b/sent_email.rb
@@ -0,0 +1,6 @@
+class SentEmail < ApplicationRecord
+  belongs_to :entity, polymorphic: true
+  enum status: { sent: 0, opened: 1, failed: 2 }
+  validates_presence_of :email_name, :status
+  validates_presence_of :message_id, unless: :failed?
+end
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