Use model timestamps when available (#18)

CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Changed
+
+- Use model timestamps (created_at, updated_at) for irontrail_changes.created_at column
+
 ## 0.0.6 - 2025-01-14
 
 ### Changed

README.md

@@ -102,6 +102,10 @@ Enabling/disabling IronTrail in specs works by replacing the trigger function in
 with a dummy no-op function or with the real function and it won't add or drop triggers from
 any tables.
 
+The `created_at` column of the `irontrail_changes` table is determined from the model timestamp attributes
+(`created_at` for inserts and `updated_at` for updates) if they're present.
+There is a caveat for delete operations: the value will always be the current timestamp from the database. This makes it impossible to mock for that scenario.
+
 ## Rake tasks
 
 IronTrail comes with a few handy rake tasks you can use in your dev, test and

lib/iron_trail/irontrail_log_row_function.sql

@@ -11,10 +11,12 @@ DECLARE
   new_obj JSONB;
   actor_type TEXT;
   actor_id TEXT;
+  created_at TIMESTAMP;
 
   err_text TEXT; err_detail TEXT; err_hint TEXT; err_ctx TEXT;
 BEGIN
     SELECT split_part(split_part(current_query(), '/*IronTrail ', 2), ' IronTrail*/', 1) INTO it_meta;
+
     IF (it_meta <> '') THEN
       it_meta_obj = it_meta::JSONB;
 
@@ -28,17 +30,30 @@ BEGIN
       END IF;
     END IF;
 
+    old_obj = row_to_json(OLD);
+    new_obj = row_to_json(NEW);
+
+    IF (TG_OP = 'INSERT' AND new_obj ? 'created_at') THEN
+      created_at = NEW.created_at;
+    ELSIF (TG_OP = 'UPDATE' AND new_obj ? 'updated_at') THEN
+      created_at = NEW.updated_at;
+    END IF;
+
+    IF (created_at IS NULL) THEN
+      created_at = NOW();
+    ELSE
+      it_meta_obj = jsonb_set(COALESCE(it_meta_obj, '{}'::jsonb), array['_db_created_at'], TO_JSONB(NOW()));
+    END IF;
+
     IF (TG_OP = 'INSERT') THEN
         INSERT INTO "irontrail_changes" ("actor_id", "actor_type",
           "rec_table", "operation", "rec_id", "rec_new", "metadata", "created_at")
         VALUES (actor_id, actor_type,
-          TG_TABLE_NAME, 'i', NEW.id, row_to_json(NEW), it_meta_obj, NOW());
+          TG_TABLE_NAME, 'i', NEW.id, new_obj, it_meta_obj, created_at);
 
     ELSIF (TG_OP = 'UPDATE') THEN
         IF (OLD <> NEW) THEN
           u_changes = jsonb_build_object();
-          old_obj = row_to_json(OLD);
-          new_obj = row_to_json(NEW);
 
           FOR key IN (SELECT jsonb_object_keys(old_obj) UNION SELECT jsonb_object_keys(new_obj))
           LOOP
@@ -51,14 +66,13 @@ BEGIN
 
           INSERT INTO "irontrail_changes" ("actor_id", "actor_type", "rec_table", "operation",
             "rec_id", "rec_old", "rec_new", "rec_delta", "metadata", "created_at")
-          VALUES (actor_id, actor_type, TG_TABLE_NAME, 'u', NEW.id, row_to_json(OLD), row_to_json(NEW),
-          u_changes, it_meta_obj, NOW());
+          VALUES (actor_id, actor_type, TG_TABLE_NAME, 'u', NEW.id, old_obj, new_obj, u_changes, it_meta_obj, created_at);
 
         END IF;
     ELSIF (TG_OP = 'DELETE') THEN
         INSERT INTO "irontrail_changes" ("actor_id", "actor_type", "rec_table", "operation",
           "rec_id", "rec_old", "metadata", "created_at")
-        VALUES (actor_id, actor_type, TG_TABLE_NAME, 'd', OLD.id, row_to_json(OLD), it_meta_obj, NOW());
+        VALUES (actor_id, actor_type, TG_TABLE_NAME, 'd', OLD.id, old_obj, it_meta_obj, created_at);
 
     END IF;
     RETURN NULL;

spec/dummy_app/app/models/guitar_part.rb

@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
 class GuitarPart < ApplicationRecord
+  include IronTrail::Model
+
   belongs_to :guitar
 end

spec/dummy_app/db/migrate/20241112090542_setup_test_db.rb

@@ -18,6 +18,8 @@ def up
     create_table :guitar_parts, id: :bigserial, force: true do |t|
       t.uuid :guitar_id
       t.string :name
+
+      t.timestamps
     end
 
     create_table :matrix_pills, id: :bigserial, force: true do |t|

spec/models/guitar_spec.rb

@@ -35,6 +35,112 @@
     end
   end
 
+  describe 'model created_at and updated_at attributes' do
+    let(:guitar) { Guitar.create!(description: 'the guitar', person:) }
+    let(:fake_update_time) { '2022-02-03T18:58:01.498334Z' }
+    let!(:some_part) { guitar.guitar_parts.create!(name: 'strings') }
+    let(:trails) { some_part.iron_trails.order(id: :asc).to_a }
+
+    before do
+      travel_to(fake_update_time) do
+        some_part.update!(name: 'Strings of the Guitar')
+      end
+
+      some_part.update!(name: 'Strings')
+    end
+
+    it 'uses the model created_at for the trail created_at on inserts and updates' do
+      expect(trails).to have_attributes(count: 3)
+      expect(trails[0].created_at).to be_within(1.second).of(some_part.created_at)
+      expect(trails[1].created_at).to be_within(1.second).of(Time.parse(fake_update_time))
+      expect(trails[2].created_at).to be_within(1.second).of(some_part.updated_at)
+    end
+
+    it 'will logically have the oldest trail be the first update' do
+      oldest_trail = some_part.iron_trails.order(created_at: :asc).first
+      expect(oldest_trail.id).to eq(trails[1].id)
+    end
+
+    describe 'metadata _db_created_at injection' do
+      it 'injects original db time into metadata' do
+        current_time = Time.now
+
+        expect(trails[0].metadata).not_to be_nil
+        expect(trails[1].metadata).not_to be_nil
+        expect(trails[2].metadata).not_to be_nil
+
+        expect(trails[0].metadata).to include('_db_created_at')
+        expect(Time.parse(trails[0].metadata['_db_created_at'])).to be_within(1.second).of(current_time)
+        expect(trails[1].metadata).to include('_db_created_at')
+        expect(Time.parse(trails[1].metadata['_db_created_at'])).to be_within(1.second).of(current_time)
+        expect(trails[2].metadata).to include('_db_created_at')
+        expect(Time.parse(trails[2].metadata['_db_created_at'])).to be_within(1.second).of(current_time)
+      end
+
+      context 'when there is previous metadata present' do
+        let(:fake_update_time_with_metadata) { '2022-01-02T20:00:30.778899Z' }
+        let(:expected_metadata) { { 'foo_bar' => { 'whatever' => 'does it work?' } } }
+
+        before do
+          travel_to(fake_update_time_with_metadata) do
+            IronTrail.store_metadata(:foo_bar, { whatever: 'does it work?' })
+
+            some_part.update!(name: 'the last straw')
+          end
+
+          some_part.destroy!
+        end
+
+        it 'preserves original metadata' do
+          last_trail = trails[3]
+          expect(last_trail.metadata).not_to be_nil
+          expect(last_trail.metadata).to include('foo_bar', '_db_created_at')
+          expect(last_trail.metadata).to include(expected_metadata)
+        end
+
+        it 'keeps the original metadata untouched when db original timestamp is not stored' do
+          expect(trails[4].metadata).to eq(expected_metadata)
+        end
+      end
+
+      context 'when it is a delete operation' do
+        it 'does not inject original db time into metadata' do
+          some_part.destroy!
+          trail = some_part.iron_trails.find_by!(operation: 'd')
+          expect(trail.metadata).to be_nil
+        end
+      end
+    end
+
+    describe 'record insertion' do
+      let(:fake_insert_time) { '2021-12-14T12:34:56.010102Z' }
+
+      it 'uses the model creation time for the insert operation' do
+        part = nil
+
+        travel_to(fake_insert_time) do
+          part = guitar.guitar_parts.create!(name: 'neck')
+        end
+
+        trail = part.iron_trails.first
+        expect(trail.created_at).to be_within(1.second).of(Time.parse(fake_insert_time))
+      end
+    end
+
+    describe 'record deletion' do
+      let(:fake_delete_time) { '2023-01-22T23:24:25.262728Z' }
+
+      before do
+        travel_to(fake_delete_time) { some_part.destroy! }
+      end
+
+      it 'uses the current time for the delete operation' do
+        trail = some_part.iron_trails.find_by!(operation: 'd')
+        expect(trail.created_at).to be_within(1.second).of(Time.now)
+      end
+    end
+  end
+
   describe 'iron_trails.travel_to' do
     let(:guitar) { Guitar.create!(description: 'the guitar', person:) }
 

spec/spec_helper.rb

@@ -43,4 +43,5 @@
 
 RSpec.configure do |config|
   config.use_transactional_fixtures = true
+  config.include ActiveSupport::Testing::TimeHelpers
 end