Provides #when_commited to run instance-specific code in an ActiveRecord #after_commit callback.

This is very useful for things like enqueuing a background job that is triggered by a model changing state. Usually, it is not sufficient to enqueue the job in an #after_save hook, because there is always the chance that the save will be rolled back (or that the job gets picked up before the save is committed). You could try moving that code to an after_commit callback, but then you do not have access to the #changes to your model (they have already been applied), so it may be difficult to make decisions on whether to enqueue the job or not.

It can also be useful for running some code in the same process, but outside of the current transaction.

Include the WhenCommitted::ActiveRecord module in your model:

class Post < ActiveRecord::Base
  include WhenCommitted::ActiveRecord
end

Call #when_committed with a block of code that should run when the transaction is committed:

def update_score(new_score)
  self.score = new_score
  when_committed { Resque.enqueue(RecalculateAggregateScores, self.id) }
  self.score_changed = true
end

By default, when_committed will raise an exception if it is called outside of an ActiveRecord transaction, since the block would never be run. If you need it to also be able to run outside of a transaction (e.g. if you have multiple callsites - some in a transaction, some not), specify the run_now_if_no_transaction: true argument.

def update_score(new_score)
  self.score = new_score
  when_committed(run_now_if_no_transaction: true) {
    Resque.enqueue(RecalculateAggregateScores, self.id)
  }
  self.score_changed = true
end

Be aware that when using this argument, the order of execution changes depending on if a transaction is present or not. When a transaction is present, score will be set, then score_changed is set, then eventually the Resque call is made when the transaction commits. When a transaction is not present, score will be set, then the Resque call is made, then score_changed is set.

Add this line to your application's Gemfile:

gem 'when_committed', github: 'ShippingEasy/when_committed'

And then execute:

$ bundle

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request