add paper trail

db/migrate/20210817233439_create_versions.rb

@@ -0,0 +1,23 @@
+# frozen_string_literal: true
+# This migration creates the `versions` table, the only schema PT requires.
+# All other migrations PT provides are optional.
+class CreateVersions < ActiveRecord::Migration[6.1]
+  # The largest text column available in all supported RDBMS is
+  # 1024^3 - 1 bytes, roughly one gibibyte.  We specify a size
+  # so that MySQL will use `longtext` instead of `text`.  Otherwise,
+  # when serializing very large objects, `text` might not be big enough.
+  TEXT_BYTES = 1_073_741_823
+
+  def change
+    create_table(:versions) do |t|
+      t.string(:item_type, { null: false })
+      t.bigint(:item_id,   null: false)
+      t.string(:event,     null: false)
+      t.string(:whodunnit)
+      t.text(:object, limit: TEXT_BYTES)
+
+      t.datetime(:created_at)
+    end
+    add_index(:versions, [:item_type, :item_id])
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 2021_08_16_174637) do
+ActiveRecord::Schema.define(version: 2021_08_17_233439) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -138,6 +138,16 @@ ActiveRecord::Schema.define(version: 2021_08_16_174637) do
     t.index ["reset_password_token"], name: "index_users_on_reset_password_token", unique: true
   end
 
+  create_table "versions", force: :cascade do |t|
+    t.string "item_type", null: false
+    t.bigint "item_id", null: false
+    t.string "event", null: false
+    t.string "whodunnit"
+    t.text "object"
+    t.datetime "created_at"
+    t.index ["item_type", "item_id"], name: "index_versions_on_item_type_and_item_id"
+  end
+
   add_foreign_key "active_storage_attachments", "active_storage_blobs", column: "blob_id"
   add_foreign_key "active_storage_variant_records", "active_storage_blobs", column: "blob_id"
   add_foreign_key "balances", "currencies"