after_commit callback does not fire if the same record got updated with a different reference in the same transaction block

[marunbai]

Steps to reproduce

Here is the set up:

There are 2 simple models. Cat and Dog. Cat has a name and Dog has a name and cat_id.

Cat has an after_update callback that will update all its dogs.
Dog has an after_commit callback that will print dog barks on destroy.

The dog callback will not fire if they got called in the same transaction because ActiveRecord::ConnectionAdapters::Transaction#commit_records method will do uniq on records. Sometimes, same record could get pushed into the transaction records array with different state multiple times, like one destroyed and one persisted.

# frozen_string_literal: true

begin
  require "bundler/inline"
rescue LoadError => e
  $stderr.puts "Bundler version 1.10 or later is required. Please update your Bundler"
  raise e
end

gemfile(true) do
  source "https://rubygems.org"

  git_source(:github) { |repo| "https://github.com/#{repo}.git" }

  # Activate the gem you are reporting the issue against.
  gem "activerecord", "5.2.1"
  gem "sqlite3"
  gem "pry"
end

require "active_record"
require "minitest/autorun"
require "logger"
require "pry"

ActiveRecord::Base.establish_connection(adapter: "sqlite3", database: ":memory:")
ActiveRecord::Base.logger = Logger.new(STDOUT)

ActiveRecord::Schema.define do
  create_table :cats do |t|
    t.string :name

    t.timestamps
  end

  create_table :dogs do |t|
    t.string :name
    t.integer :cat_id

    t.timestamps
  end
end

class Cat < ActiveRecord::Base
  has_many :dogs

  after_update :update_dogs

  def update_name(name)
    self.name = name

    save!
  end

  def update_dogs
    dogs.each do |dog|
      dog.name = 'new dog'
      dog.save!
    end
  end
end

class Dog < ActiveRecord::Base
  belongs_to :cat

  after_commit :bark, on: :destroy

  def bark
    puts "dog barks"
  end
end

class BugTest < Minitest::Test
  def test_stuff
    Cat.create(:name => 'cat')
    dog = Dog.new(:name => 'dog_2')
    dog.cat = Cat.last
    dog.save

    puts'----------------------------------'
    puts'Dog should bark in this example: '
    puts

    Dog.transaction do
      dog = Dog.last
      cat = dog.cat
      cat.update_name('cat 2')

      dog.destroy
    end
  end
end

Expected behavior

after_destroy_commit callback bark should fire after dog.destroy in the transaction above.

D, [2018-12-07T10:56:59.999822 #33390] DEBUG -- :    (0.0ms)  begin transaction
D, [2018-12-07T10:57:00.000744 #33390] DEBUG -- :   Dog Load (0.2ms)  SELECT  "dogs".* FROM "dogs" ORDER BY "dogs"."id" DESC LIMIT ?  [["LIMIT", 1]]
D, [2018-12-07T10:57:00.008017 #33390] DEBUG -- :   Cat Load (0.1ms)  SELECT  "cats".* FROM "cats" WHERE "cats"."id" = ? LIMIT ?  [["id", 1], ["LIMIT", 1]]
D, [2018-12-07T10:57:00.009899 #33390] DEBUG -- :   Cat Update (0.1ms)  UPDATE "cats" SET "name" = ?, "updated_at" = ? WHERE "cats"."id" = ?  [["name", "cat 2"], ["updated_at", "2018-12-07 15:57:00.008533"], ["id", 1]]
D, [2018-12-07T10:57:00.015809 #33390] DEBUG -- :   Dog Load (0.1ms)  SELECT "dogs".* FROM "dogs" WHERE "dogs"."cat_id" = ?  [["cat_id", 1]]
D, [2018-12-07T10:57:00.017123 #33390] DEBUG -- :   Dog Update (0.2ms)  UPDATE "dogs" SET "name" = ?, "updated_at" = ? WHERE "dogs"."id" = ?  [["name", "new dog"], ["updated_at", "2018-12-07 15:57:00.016259"], ["id", 1]]
D, [2018-12-07T10:57:00.018520 #33390] DEBUG -- :   Dog Destroy (0.2ms)  DELETE FROM "dogs" WHERE "dogs"."id" = ?  [["id", 1]]
D, [2018-12-07T10:57:00.018953 #33390] DEBUG -- :    (0.0ms)  commit transaction
dog barks

Actual behavior

after_destroy_commit callback bark does not fire in the example

D, [2018-12-07T10:56:59.999822 #33390] DEBUG -- :    (0.0ms)  begin transaction
D, [2018-12-07T10:57:00.000744 #33390] DEBUG -- :   Dog Load (0.2ms)  SELECT  "dogs".* FROM "dogs" ORDER BY "dogs"."id" DESC LIMIT ?  [["LIMIT", 1]]
D, [2018-12-07T10:57:00.008017 #33390] DEBUG -- :   Cat Load (0.1ms)  SELECT  "cats".* FROM "cats" WHERE "cats"."id" = ? LIMIT ?  [["id", 1], ["LIMIT", 1]]
D, [2018-12-07T10:57:00.009899 #33390] DEBUG -- :   Cat Update (0.1ms)  UPDATE "cats" SET "name" = ?, "updated_at" = ? WHERE "cats"."id" = ?  [["name", "cat 2"], ["updated_at", "2018-12-07 15:57:00.008533"], ["id", 1]]
D, [2018-12-07T10:57:00.015809 #33390] DEBUG -- :   Dog Load (0.1ms)  SELECT "dogs".* FROM "dogs" WHERE "dogs"."cat_id" = ?  [["cat_id", 1]]
D, [2018-12-07T10:57:00.017123 #33390] DEBUG -- :   Dog Update (0.2ms)  UPDATE "dogs" SET "name" = ?, "updated_at" = ? WHERE "dogs"."id" = ?  [["name", "new dog"], ["updated_at", "2018-12-07 15:57:00.016259"], ["id", 1]]
D, [2018-12-07T10:57:00.018520 #33390] DEBUG -- :   Dog Destroy (0.2ms)  DELETE FROM "dogs" WHERE "dogs"."id" = ?  [["id", 1]]
D, [2018-12-07T10:57:00.018953 #33390] DEBUG -- :    (0.0ms)  commit transaction

System configuration

Rails version: 5.2.1

Ruby version: 2.2.4

[rails-bot]

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