SingleActionService

Implementation of a Service Object pattern in Ruby.

Installation

Add this line to your application's Gemfile:

gem 'single_action_service'

And then execute:

$ bundle

Or install it yourself as:

$ gem install single_action_service

Usage

Create an inheritor from a SingleActionService::Base with a single method named call

class Summator < SingleActionService::Base
  def call
  end
end

Create a constructor with parameters

class Summator < SingleActionService::Base
  def initialize(x, y)
    @x = x
    @y = y
  end
end

or pass them to the call method

class Summator < SingleActionService::Base
  def call(x, y)
  end
end

Perform the action and return the result by calling success(data = nil)

class Summator < SingleActionService::Base
  def call(x, y)
    sum = x + y
    success(sum)
  end
end

or return the error based on the validations by calling error(data: nil, code: nil)

class Summator < SingleActionService::Base
  NIL_NUMBERS_ERROR = :nil_numbers_error

  def call(x, y)
    if x.nil? || y.nil?
      return error(code: NIL_NUMBERS_ERROR)
    end
  end
end

Call the service and process a result

summator = Summator.new
result = summator.call(1, 2)

if result.success?
  result.data
else
  result.error_code
end

Or you can use a data! method if you want to throw an exception when an error has occurred:

begin
  result = Summator.new.call(1, 2).data!
rescue SingleActionService::InvalidResult => e
  e.result.error_code
end

You can define a list of errors of a service by calling a self.errors(errors_data) method.
For each error, a method #{error_name}_error(data = nil) will be generated to instantiate the result with the appropriate code and optional data:

class Summator < SingleActionService::Base
  errors [
    { name: :nil_numbers, code: :nil_numbers_error }
  ]

  def call(x, y)
    if x.nil? || y.nil?
      return nil_numbers_error
    end
  end
end

You can check for the specific error calling an autogenerated checking method of the result:

result = Summator.new.call(nil, nil)
result.nil_numbers_error? # true

API Reference