How to tell if already within a database transaction in ruby on rails?

activerecord, mysql, ruby, ruby-on-rails, transactions

Solution

You can use

ActiveRecord::Base.connection.open_transactions

to see if your method is executed in a transaction.

`ActiveRecord::Base.connection.open_transactions == 0` implies that your method is not executed in a transaction. Anything greater than 0 would imply that your method is executed in a transaction. For example `ActiveRecord::Base.connection.open_transactions > 0`

Update:

from rails documentation

`all database statements in the nested transaction block become part of the parent transaction`

So number of open transaction will be one even if you are in a nested transaction.

This is what i got in my console

ActiveRecord::Base.transaction do
   User.first.update_attribute(:first_name, "something")
   ActiveRecord::Base.transaction do
       User.first.update_attribute(:last_name, "something")
       p ActiveRecord::Base.connection.open_transactions
   end
end


  (0.3ms)  BEGIN
  User Load (0.8ms)  SELECT "users".* FROM "users" LIMIT 1
  (0.8ms)  UPDATE "users" SET "first_name" = 'something', "updated_at" = '2013-11-20 18:33:52.254088' WHERE "users"."id" = 1
  User Load (0.5ms)  SELECT "users".* FROM "users" LIMIT 1
  (0.4ms)  UPDATE "users" SET "last_name" = 'something', "updated_at" = '2013-11-20 18:33:52.266976' WHERE "users"."id" = 1
  1
  (14.2ms)  COMMIT
  => 1

Problem

``` ActiveRecord::Base.transaction do Foo.new.bar end Foo.new.baz ``` Can I determine programmatically from within the `bar()` or `baz()` methods if a transaction is already taking place? Looking for something that might look like `ActiveRecord::Base.within_transaction?`, that would return `true` when called from `bar()` and `false` when called for `baz()`. In case it is relevant, I'm using a mysql database with the mysql2 gem, and am ok with a solution that works only for mysql.

Original source