service_example.rb

class QuoteGroupsController << QuotingController
    ...
  
    def add_tests
      Services::AddTestsToQuoteGroup.new.call(
        attempt_id: params[:attempt_id],
        test_ids: params[:test_ids],
        quote_group_id: params[:quote_group_id],
      ) do |result|
        result.failure do |errors|
          render status: 500, json: errors
        end
        result.success do
          render json: {message: "ok"}
        end
      end
    end
  
    ...
end

module Quoting
  module Services
    class AddTestsToQuoteGroup < Service
      Schema = Dry::Validation.Params do
        configure do
          def self.messages
            super.merge(
              en: {errors: {
                attempt_is_preliminary: "Quote Attempt must be preliminary",
                tests_are_active: "All tests must be active",
                quote_group_is_active: "Selected quote group must be active",
              }},
            )
          end
        end

        required(:attempt_id).filled(:int?)
        required(:quote_group_id).filled(:int?)
        required(:test_ids, Types::Integer).filled(:array?)

        validate(attempt_is_preliminary: [:attempt_id]) do |attempt_id|
          Attempt.find(attempt_id).preliminary?
        end

        validate(tests_are_active: [:test_ids]) do |test_ids|
          Testing::Test.find_active(test_ids).count == test_ids.size
        end

        validate(quote_group_is_active: [:attempt_id, :quote_group_id]) do |attempt_id, quote_group_id|
          quote_group = Attempt.find(attempt_id).quote_groups.find(quote_group_id)
          !quote_group.expired? && !quote_group.group_placeholder.expired?
        end
      end

      def call(attempt_id:, test_ids:, quote_group_id:)
        result = Schema.({
          attempt_id: attempt_id,
          test_ids: test_ids,
          quote_group_id: quote_group_id,
        })
        if result.errors.any?
          Failure(result.errors)
        else
          attempt = Attempt.find attempt_id
          ...
          ...
          Success(quote_group)
        end
      end
    end
  end
end

------- 

require 'dry-monads'
require 'dry/matcher/result_matcher'
require "dry-validation"

class Service 
  include Dry::Monads::Result::Mixin

  class ServiceFailed < StandardError ; end

  def self.inherited(base)
    super
    base.include(Dry::Matcher.for(:call, with: Dry::Matcher::ResultMatcher))
  end

end