after_commit everywhere

Allows to use ActiveRecord transactional callbacks outside of ActiveRecord models, literally everywhere in your application.

Inspired by these articles:

• https://evilmartians.com/chronicles/rails-after_commit-everywhere
• https://blog.arkency.com/2015/10/run-it-in-background-job-after-commit/

Installation

Add this line to your application's Gemfile:

gem 'after_commit_everywhere'

And then execute:

$ bundle

Or install it yourself as:

$ gem install after_commit_everywhere

Usage

Recommended usage is to include it to your base service class or anything:

class ServiceObjectBtw
  include AfterCommitEverywhere

  def call
    ActiveRecord::Base.transaction do
      after_commit { puts "We're all done!" }
    end
  end
end

Or just extend it whenever you need it:

extend AfterCommitEverywhere

ActiveRecord::Base.transaction do
  after_commit { puts "We're all done!" }
end

Or call it directly on module:

AfterCommitEverywhere.after_commit { puts "We're all done!" }

That's it!

But the main benefit is that it works with nested transaction blocks (may be even spread across many files in your codebase):

include AfterCommitEverywhere

ActiveRecord::Base.transaction do
  puts "We're in transaction now"

  ActiveRecord::Base.transaction do
    puts "More transactions"
    after_commit { puts "We're all done!" }
  end

  puts "Still in transaction…"
end

Will output:

We're in transaction now
More transactions
Still in transaction…
We're all done!

Available callbacks

after_commit

Will be executed right after outermost transaction have been successfully committed and data become available to other DBMS clients.

If called outside transaction will execute callback immediately.

before_commit

Will be executed right before outermost transaction will be commited (I can't imagine use case for it but if you can, please open a pull request or issue).

If called outside transaction will execute callback immediately.

Supported only starting from ActiveRecord 5.0.

after_rollback

Will be executed right after transaction in which it have been declared was rolled back (this might be nested savepoint transaction block with requires_new: true).

If called outside transaction will raise an exception!

Please keep in mind ActiveRecord's limitations for rolling back nested transactions. See in_transaction for a workaround to this limitation.

Available helper methods

in_transaction

Makes sure the provided block is running in a transaction.

This method aims to provide clearer intention than a typical ActiveRecord::Base.transaction block - in_transaction only cares that some transaction is present, not that a transaction is nested in any way.

If a transaction is present, it will yield without taking any action. Note that this means ActiveRecord::Rollback errors will not be trapped by in_transaction but will propagate up to the nearest parent transaction block.

If no transaction is present, the provided block will open a new transaction.

class ServiceObjectBtw
  include AfterCommitEverywhere

  def call
    in_transaction do
      an_update
      another_update
      after_commit { puts "We're all done!" }
    end
  end
end

Our service object can run its database operations safely when run in isolation.

ServiceObjectBtw.new.call # This opens a new #transaction block

If it is later called from code already wrapped in a transaction, the existing transaction will be utilized without any nesting:

ActiveRecord::Base.transaction do
  new_update
  next_update
  # This no longer opens a new #transaction block, because one is already present
  ServiceObjectBtw.new.call
end

This can be called directly on the module as well:

AfterCommitEverywhere.in_transaction do
  AfterCommitEverywhere.after_commit { puts "We're all done!" }
end

in_transaction?

Returns true when called inside an open transaction, false otherwise.

def check_for_transaction
  if in_transaction?
    puts "We're in a transaction!"
  else
    puts "We're not in a transaction..."
  end
end

check_for_transaction
# => prints "We're not in a transaction..."

in_transaction do
  check_for_transaction
end
# => prints "We're in a transaction!"

Available callback options

• without_tx allows to change default callback behavior if called without transaction open.

  Available values:

  • :execute to execute callback immediately
  • :warn_and_execute to print warning and execute immediately
  • :raise to raise an exception instead of executing

• prepend puts the callback at the head of the callback chain, instead of at the end.

FAQ

Does it works with transactional_test or DatabaseCleaner

Yes.

Be aware of mental traps

While it is convenient to have after_commit method at a class level to be able to call it from anywhere, take care not to call it on models.

So, DO NOT DO THIS:

class Post < ActiveRecord::Base
  def self.bulk_ops
    find_each do
      after_commit { raise "Some doesn't expect that this screw up everything, but they should" }
    end
  end
end

By calling the class level after_commit method on models, you're effectively adding callback for all Post instances, including future ones.

See #13 for details.

But what if I want to use it inside models anyway?

In class-level methods call AfterCommitEverywhere.after_commit directly:

class Post < ActiveRecord::Base
  def self.bulk_ops
    find_each do
       AfterCommitEverywhere.after_commit { puts "Now it works as expected!" }
    end
  end
end

For usage in instance-level methods include this module to your model class (or right into your ApplicationRecord):

class Post < ActiveRecord::Base
  include AfterCommitEverywhere

  def do_some_stuff
    after_commit { puts "Now it works!" }
  end
end

However, if you do something in models that requires defining such ad-hoc transactional callbacks, it may indicate that your models have too many responsibilities and these methods should be extracted to separate specialized layers (service objects, etc).

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install.

Releasing new versions

1. Bump version number in lib/after_commit_everywhere/version.rb

   In case of pre-releases keep in mind rubygems/rubygems#3086 and check version with command like Gem::Version.new(AfterCommitEverywhere::VERSION).to_s

2. Fill CHANGELOG.md with missing changes, add header with version and date.

3. Make a commit:

   git add lib/after_commit_everywhere/version.rb CHANGELOG.md
   version=$(ruby -r ./lib/after_commit_everywhere/version.rb -e "puts Gem::Version.new(AfterCommitEverywhere::VERSION)")
   git commit --message="${version}: " --edit

4. Create annotated tag:

   git tag v${version} --annotate --message="${version}: " --edit --sign

5. Fill version name into subject line and (optionally) some description (list of changes will be taken from CHANGELOG.md and appended automatically)

6. Push it:

   git push --follow-tags

7. GitHub Actions will create a new release, build and push gem into rubygems.org! You're done!

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/Envek/after_commit_everywhere.

License

The gem is available as open source under the terms of the MIT License.