ApplicationService for controllers

application_service.rb

module ApplicationService
  extend ActiveSupport::Concern

  included do
    attr_accessor :request

    def self.call(*args)
      # The last caller should be a controller and by using
      # the binding_of_caller gem, we can grab that instance.
      ctrl = binding.of_caller(1)
      
      # Lets pass the request and response objects and methods
      # over into the service for it to use. This will allow
      # us access to methods such as `redirect_to` and `flash`.
      request = ctrl.eval "request"
      _request = ctrl.eval "@_request"
      _response = ctrl.eval "@_response"
      
      # Create a new object of the service and pass in the
      # request and response objects for it to be aware of.
      # Then, we find a method called `#call` and call it.
      new(request, _request, _response).call(*args)
    end

    # Create the new object and make sure it is aware of
    # the request and response objects.
    def initialize(request, _request, _response)
      @request = request
      @_request = _request
      @_response = _response
    end
    
    # All services are expected to have a `#call` method,
    # therefore if none are found, then fail with a
    # NotImplementedError
    def call(*)
      fail NotImplementedError
    end
  end
end