Rails ActiveRecord Transaction vs Class Transaction

Question

I have a doubt about Rails Transaction type. What the diffence between them and whem to use each one ?

Active Record Transactions

ActiveRecord::Base.transaction do
    david.withdrawal(100)
    mary.deposit(100)
end

Class Transactions

Account.transaction do
    balance.save!
    account.save!
end

Instance Transactions

account.transaction do
    balance.save!
    account.save!
end

Thank you very much in advance!

Answer 1

AR Transaction is the Class Transaction

Account < ActiveRecord::Base
end

Account.transaction(block) == ActiveRecord::Base.transaction(block)

http://api.rubyonrails.org/classes/ActiveRecord/Transactions/ClassMethods.html https://apidock.com/rails/ActiveRecord/Transactions/ClassMethods/transaction

Instance Transaction is a convenience method

The instance method of DB transactions is a convenience method for more syntactically beautiful code.

You could do this instead.

account = Account.find(1)
ActiveRecord::Base.transaction do
  account.save!
end

And it would be the same for any of the above. Either way, it's generating SQL code in a transaction.

The proof is in the source code of the instance method for transactions.

# File activerecord/lib/active_record/transactions.rb, line 276
def transaction(options = {}, &block)
  self.class.transaction(options, &block)
end

https://apidock.com/rails/v4.2.7/ActiveRecord/Transactions/transaction