From 6ddba9b46c1d307ea7e03d753d0988183b9cb80c Mon Sep 17 00:00:00 2001
From: bogdanvlviv <bogdanvlviv@gmail.com>
Date: Mon, 11 Dec 2017 23:56:07 +0200
Subject: Fix conflicts `counter_cache` with `touch: true` by optimistic
 locking.

  ```
  # create_table :posts do |t|
  #   t.integer :comments_count, default: 0
  #   t.integer :lock_version
  #   t.timestamps
  # end
  class Post < ApplicationRecord
  end

  # create_table :comments do |t|
  #   t.belongs_to :post
  # end
  class Comment < ApplicationRecord
    belongs_to :post, touch: true, counter_cache: true
  end
  ```

  Before:
  ```
  post = Post.create!
  # => begin transaction
       INSERT INTO "posts" ("created_at", "updated_at", "lock_version")
       VALUES ("2017-12-11 21:27:11.387397", "2017-12-11 21:27:11.387397", 0)
       commit transaction

  comment = Comment.create!(post: post)
  # => begin transaction
       INSERT INTO "comments" ("post_id") VALUES (1)

       UPDATE "posts" SET "comments_count" = COALESCE("comments_count", 0) + 1,
       "lock_version" = COALESCE("lock_version", 0) + 1 WHERE "posts"."id" = 1

       UPDATE "posts" SET "updated_at" = '2017-12-11 21:27:11.398330',
       "lock_version" = 1 WHERE "posts"."id" = 1 AND "posts"."lock_version" = 0
       rollback transaction
  # => ActiveRecord::StaleObjectError: Attempted to touch a stale object: Post.

  Comment.take.destroy!
  # => begin transaction
       DELETE FROM "comments" WHERE "comments"."id" = 1

       UPDATE "posts" SET "comments_count" = COALESCE("comments_count", 0) - 1,
       "lock_version" = COALESCE("lock_version", 0) + 1 WHERE "posts"."id" = 1

       UPDATE "posts" SET "updated_at" = '2017-12-11 21:42:47.785901',
       "lock_version" = 1 WHERE "posts"."id" = 1 AND "posts"."lock_version" = 0
       rollback transaction
  # => ActiveRecord::StaleObjectError: Attempted to touch a stale object: Post.
  ```

  After:
  ```
  post = Post.create!
  # => begin transaction
       INSERT INTO "posts" ("created_at", "updated_at", "lock_version")
       VALUES ("2017-12-11 21:27:11.387397", "2017-12-11 21:27:11.387397", 0)
       commit transaction

  comment = Comment.create!(post: post)
  # => begin transaction
       INSERT INTO "comments" ("post_id") VALUES (1)

       UPDATE "posts" SET "comments_count" = COALESCE("comments_count", 0) + 1,
       "lock_version" = COALESCE("lock_version", 0) + 1,
       "updated_at" = '2017-12-11 21:37:09.802642' WHERE "posts"."id" = 1
       commit transaction

  comment.destroy!
  # => begin transaction
       DELETE FROM "comments" WHERE "comments"."id" = 1

       UPDATE "posts" SET "comments_count" = COALESCE("comments_count", 0) - 1,
       "lock_version" = COALESCE("lock_version", 0) + 1,
       "updated_at" = '2017-12-11 21:39:02.685520' WHERE "posts"."id" = 1
       commit transaction
  ```

  Fixes #31199.
---
 .../lib/active_record/associations/belongs_to_association.rb   |  4 ++--
 .../lib/active_record/associations/builder/belongs_to.rb       | 10 +++++++---
 2 files changed, 9 insertions(+), 5 deletions(-)

(limited to 'activerecord/lib/active_record')

diff --git a/activerecord/lib/active_record/associations/belongs_to_association.rb b/activerecord/lib/active_record/associations/belongs_to_association.rb
index ba54cd8f49..68c608df13 100644
--- a/activerecord/lib/active_record/associations/belongs_to_association.rb
+++ b/activerecord/lib/active_record/associations/belongs_to_association.rb
@@ -49,9 +49,9 @@ module ActiveRecord
         def update_counters(by)
           if require_counter_update? && foreign_key_present?
             if target && !stale_target?
-              target.increment!(reflection.counter_cache_column, by)
+              target.increment!(reflection.counter_cache_column, by, touch: reflection.options[:touch])
             else
-              klass.update_counters(target_id, reflection.counter_cache_column => by)
+              klass.update_counters(target_id, reflection.counter_cache_column => by, touch: reflection.options[:touch])
             end
           end
         end
diff --git a/activerecord/lib/active_record/associations/builder/belongs_to.rb b/activerecord/lib/active_record/associations/builder/belongs_to.rb
index 9904ee4bed..c161454c1a 100644
--- a/activerecord/lib/active_record/associations/builder/belongs_to.rb
+++ b/activerecord/lib/active_record/associations/builder/belongs_to.rb
@@ -114,9 +114,13 @@ module ActiveRecord::Associations::Builder # :nodoc:
         BelongsTo.touch_record(record, record.send(changes_method), foreign_key, n, touch, belongs_to_touch_method)
       }}
 
-      model.after_save    callback.(:saved_changes), if: :saved_changes?
-      model.after_touch   callback.(:changes_to_save)
-      model.after_destroy callback.(:changes_to_save)
+      unless reflection.counter_cache_column
+        model.after_create callback.(:saved_changes), if: :saved_changes?
+        model.after_destroy callback.(:changes_to_save)
+      end
+
+      model.after_update callback.(:saved_changes), if: :saved_changes?
+      model.after_touch callback.(:changes_to_save)
     end
 
     def self.add_default_callbacks(model, reflection)
-- 
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