ActiveCommand

ActiveCommand adds the ability to use the command pattern commonly seen in CQRS.

Add this line to your application's Gemfile:

gem 'activecommand'

And then execute:

$ bundle

Or install it yourself as:

$ gem install activecommand

Developing a new command is pretty straight forward.

First create your command. Perhaps adding it to a commands folder under app, if you are using rails.

app
  - commands
    - SubmitOrderCommand.rb

Then inherit from the base command class and implement an execute method. The following example is assuming the Order is an ActiveRecord model and has a submit? method.

class SubmitOrderCommand < ActiveCommand::Command

  attribute :order_id, String

  validates :order_id, presence: true

  def execute
    order = Order.find(order_id)
    if order.submit?
      Emailer.send_order_submitted_notification_for(order)
    else
      raise OrderSubmitError, "Something went wrong submitting the order '#{order_id}'"
    end
  end
end

Add the desired implementation to the execute method. In this case, what ever is needed to submit an order. To execute the command, instantiate it and execute it using the CommandBus. The returned value from executing the command is a CommandResult object. The CommandResult will tell you if the command was successful or not.

submit_order_command = SubmitOrderCommand.new(:order_id => "ABC123")
cr = ActiveCommand::CommandBus.execute(submit_order_command)
if cr.success?
  redirect "/"
else
  render :submit
end

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.

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