Uncouple

Uncouple your business logic from Rails or whatever other framework you may be using.

Add this line to your application's Gemfile:

gem 'uncouple'

If you're on rails:

gem 'uncouple', require: 'uncouple/rails'

And then execute:

$ bundle

Or install it yourself as:

$ gem install uncouple

Create actions in app/actions/:model_name/:action_name. If you're on rails, you can use the included generator:

rails generate uncouple:action metric/create

Use actions to encapsulate your business logic.

# app/actions/metric/create_action.rb
class Metric::CreateAction < Uncouple::Action

  attr_reader :metric

  def perform
    create_metric!
    notify! if params[:notify]
  end

  def create_metric!
    @metric = Metric.create(metric_params)
  end

  def notify!
    NewMetricMailer.notification(metric).deliver
  end

  def success?
    metric.try(:persisted?)
  end

private

  def metric_params
    params.require(:metric).permit(:name, :value)
  end

end

In the console:

action = Metric::CreateAction.new(metric: { name: "RPM", value: 5 })
action.perform
action.success?

Or in the controller using the Uncouple::ActionPerformer

# app/controllers/metrics_controller.rb
class MetricsController < ApplicationController

  include Uncouple::ActionPerformer

  def create
    perform Metric::CreateAction do
      return redirect_to(metrics_path)
    end
    render :new
  end

end

If available, Uncouple::ActionPerformer injects your controller's current_user into the action and calls perform_with_authorization under the hood. Overwrite authorize! in your action to ensure the user has permission to call the action.

Actions also include a current_user helper method.

For example, you can use pundit like this:

class Metric::CreateAction < Uncouple::Action

  def authorize!
    Pundit.authorize(current_user, Metric, :create?)
  end

  # ...

end

Version 0.2.0 adds support for instrumentation on perform and authorize! using ActiveSupport::Notifications. Subscribe to notifications using an initializer, and do whatever you like with the data.

# config/initializers/notifications.rb
ActiveSupport::Notifications.subscribe /.*(Action)#(perform|authorize!)/ do |*args|
  event = ActiveSupport::Notifications::Event.new(*args)
  Rails.logger.info "#{event.name} completed in #{event.duration}ms"
end

#=> Metric::IndexAction#perform completed in 8.253ms

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. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Tests can be run with rspec:

bundle exec rspec

Bug reports and pull requests are welcome on GitHub at https://github.com/citrus/uncouple. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

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