SimpleServiceObject

A simple command pattern implementation in Ruby.

Add this line to your application's Gemfile:

gem 'simple_service_object'

And then execute:

$ bundle

Or install it yourself as:

$ gem install simple_service_object

Write your service object class, which must inherit from SimpleServiceObject::Base and must define a call instance method.

  class SubscribeUser < SimpleServiceObject::Base
    def initialize(user)
      @user = user
    end

    def call
      add_user_to_newsletter_recipients(@user)
      notify_user(@user)
    end

    private

    def add_user_to_newsletter_recipients(user)
      # ...
    end

    def notify_user(user)
      # ...
    end
  end

To run your command, simply:

  SubscribeUser.call(my_new_user) # arguments are passed to your class '#initialize' method

You can add errors using the errors method, which exposes to you an array of errors.

class CalculateSquareRoot < SimpleServiceObject::Base
  def initialize(number)
    @number = number
  end

  def call
    if number < 0
      errors.push("Cannot calculate square root!")
      return
    end
    Math.sqrt(@number)
  end
end

  result = CalculateSquareRoot.call(9)
  result.success? # true
  result.failure? # false
  result.errors # []
  result.value # 3.0

  result = CalculateSquareRoot.call(-1)
  result.success? # false
  result.failure? # true
  result.errors # ["Cannot calculate square root!"]
  result.value # nil

You can also use .call! instead of .call. If there aren't any errors, it will return the value, otherwise it will raise an exception.

  CalculateSquareRoot.call!(9) # 3.0
  CalculateSquareRoot.call!(-1) # raises SimpleServiceObject::FailureError

After checking out the repo, run bin/setup to install dependencies. Then, run rake to run rubocop and 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/welaika/simple_service_object. 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.

made with ❤️ and ☕️ by weLaika

Copyright © 2016-2019 weLaika

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