Adds the Outbox model and its respective migration file

lib/templates/create_outboxable_outboxes.rb

@@ -0,0 +1,25 @@
+class CreateOutboxableOutboxes < ActiveRecord::Migration[7.0]
+  def change
+    enable_extension 'pgcrypto' unless extension_enabled?('pgcrypto')
+
+    create_table :outboxes, id: :uuid, default: 'gen_random_uuid()' do |t|
+      t.integer :status, null: false, default: 0
+
+      t.string :exchange, null: false, default: ''
+      t.string :routing_key, null: false, default: ''
+
+      t.integer  :attempts, null: false, default: 0
+      t.datetime :last_attempted_at, null: true
+      t.datetime :retry_at, null: true
+
+      t.jsonb :payload, default: {}
+      t.jsonb :headers, default: {}
+
+      t.integer :size, null: false, default: 0
+
+      t.references :outboxable, polymorphic: true, null: true 
+
+      t.timestamps
+    end
+  end
+end

lib/templates/outbox.rb

@@ -0,0 +1,32 @@
+class Outbox < ApplicationRecord
+  attribute :allow_publish, :boolean, default: true
+
+  # Callbacks
+  after_commit :publish, if: :allow_publish?
+  before_save :check_publishing
+
+  # Enums
+  enum status: { pending: 0, published: 1, failed: 2 }
+  enum size: { single: 0, batch: 1 }
+
+  # Validations
+  validates :payload, presence: true
+  validates :exchange, presence: true
+  validates :routing_key, presence: true
+
+  # Associations
+  belongs_to :outboxable, polymorphic: true, optional: true
+
+  def increment_attempt
+    self.attempts = attempts + 1
+    self.last_attempted_at = Time.zone.now
+  end
+
+  def publish
+    Outboxable::Worker.perform_async(id)
+  end
+
+  def check_publishing
+    self.allow_publish = false if published?
+  end
+end