This abstract class specifies the interface to interact with the current transaction state.

Any other methods not specified here are considered to be private interfaces.

Callbacks

After updating the database state, you may sometimes need to perform some extra work, or reflect these changes in a remote system like clearing or updating a cache:

def publish_article(article)
  article.update!(published: true)
  NotificationService.article_published(article)
end

The above code works but has one important flaw, which is that it no longer works properly if called inside a transaction, as it will interact with the remote system before the changes are persisted:

Article.transaction do
  article = create_article(article)
  publish_article(article)
end

The callbacks offered by ActiveRecord::Transaction allow to rewriting this method in a way that is compatible with transactions:

def publish_article(article)
  article.update!(published: true)
  Article.current_transaction.after_commit do
    NotificationService.article_published(article)
  end
end

In the above example, if publish_article is called inside a transaction, the callback will be invoked after the transaction is successfully committed, and if called outside a transaction, the callback will be invoked immediately.

Caveats

When using after_commit callbacks, it is important to note that if the callback raises an error, the transaction won’t be rolled back. Relying solely on these to synchronize state between multiple systems may lead to consistency issues.

Methods

Instance Public methods

after_commit(&block)

Registers a block to be called after the current transaction is fully committed.

If there is no currently open transactions, the block is called immediately.

If the current transaction has a parent transaction, the callback is transferred to the parent when the current transaction commits, or dropped when the current transaction is rolled back. This operation is repeated until the outermost transaction is reached.

If the callback raises an error, the transaction remains committed.

πŸ“ Source code 
# File activerecord/lib/active_record/transaction.rb, line 93
    def after_commit(&block)
      (@callbacks ||= []) << Callback.new(:after_commit, block)
    end
πŸ”Ž See on GitHub

after_rollback(&block)

Registers a block to be called after the current transaction is rolled back.

If there is no currently open transactions, the block is never called.

If the current transaction is successfully committed but has a parent transaction, the callback is automatically added to the parent transaction.

If the entire chain of nested transactions are all successfully committed, the block is never called.

πŸ“ Source code 
# File activerecord/lib/active_record/transaction.rb, line 106
    def after_rollback(&block)
      (@callbacks ||= []) << Callback.new(:after_rollback, block)
    end
πŸ”Ž See on GitHub

before_commit(&block)

Registers a block to be called before the current transaction is fully committed.

If there is no currently open transactions, the block is called immediately.

If the current transaction has a parent transaction, the callback is transferred to the parent when the current transaction commits, or dropped when the current transaction is rolled back. This operation is repeated until the outermost transaction is reached.

If the callback raises an error, the transaction is rolled back.

πŸ“ Source code 
# File activerecord/lib/active_record/transaction.rb, line 80
    def before_commit(&block)
      (@callbacks ||= []) << Callback.new(:before_commit, block)
    end
πŸ”Ž See on GitHub

blank?()

Alias for: closed?

closed?()

Returns true if no transaction is currently active.

Also aliased as: blank?
πŸ“ Source code 
# File activerecord/lib/active_record/transaction.rb, line 116
    def closed?
      false
    end
πŸ”Ž See on GitHub

open?()

Returns true if a transaction was started.

πŸ“ Source code 
# File activerecord/lib/active_record/transaction.rb, line 111
    def open?
      true
    end
πŸ”Ž See on GitHub

uuid()

Returns a UUID for this transaction.

πŸ“ Source code 
# File activerecord/lib/active_record/transaction.rb, line 122
    def uuid
      @uuid ||= Digest::UUID.uuid_v4
    end
πŸ”Ž See on GitHub