Rails Observer Alternatives for 4.0

Question

With Observers officially removed from Rails 4.0, I\'m curious what other developers are using in their place. (Other than using the extracted gem.) While Observers were cer

Answer 1

How about using a PORO instead?

The logic behind this is that your 'extra actions on save' are likely going to be business logic. This I like to keep separate from both AR models (which should be as simple as possible) and controllers (which are bothersome to test properly)

class LoggedUpdater

  def self.save!(record)
    record.save!
    #log the change here
  end

end

And simply call it as such:

LoggedUpdater.save!(user)

You could even expand on it, by injecting extra post-save action objects

LoggedUpdater.save(user, [EmailLogger.new, MongoLogger.new])

And to give an example of the 'extras'. You might want to spiffy them up a bit though:

class EmailLogger
  def call(msg)
    #send email with msg
  end
end

If you like this approach, I recommend a read of Bryan Helmkamps 7 Patterns blog post.

EDIT: I should also mention that the above solution allows for adding transaction logic as well when needed. E.g. with ActiveRecord and a supported database:

class LoggedUpdater

  def self.save!([records])
    ActiveRecord::Base.transaction do
      records.each(&:save!)
      #log the changes here
    end
  end

end