Service class bare bones

gistfile1.txt

# frozen_string_literal: true

#
# Example usage: 
# result = Gizmo.call(**params)
# result.success? ? succeed_path : failure_path

# This service class: 
# Is based on the Interactor gem
# * Validates its parameters using ActiveRecord pieces
# * Will not execute the service if the params are invalid
# * Runs whatever code is in the `execute` method if params are valid
# * Unifies how service classes are called from other code and what is returned 
# * Ssupport memoization 

module Servo
  module Callable
    extend ActiveSupport::Concern

    included do
      extend ActiveModel::Callbacks
      include ActiveModel::Validations
      include Interactor
      include Memery

      define_model_callbacks :validation

      def call
        if valid?
          result           = execute
          context.result ||= result
          return
        end

        context.fail!(
          errors:         errors,
          error_messages: errors.full_messages
        )
      end

      def execute; end

      def method_missing(method, *args, &block)
        context.public_send(method, *args, &block)
      end

      #
      # The `context` responds to any method. If the context
      # lacks the key, it returns nil.
      def respond_to_missing?(_method_name, _include_private = false)
        true
      end

      def valid?
        run_callbacks :validation do
          super
        end
      end
    end
  end
end

class Gizmo
  include Servo::Callable

  validates :name, presence: true

  def execute
    true
  end
end