Service example

api_controller.rb

# project/app/controllers/api_controller.rb
class ApiController
  def render_response(serializer:, result:)
    if result.success?
      render json: serializer.new(result.value!).serializable_hash
    else
      render json: { errors: [result.failure] }
    end
  end
end

create_user_service.rb

# project/app/services/create_user_service.rb
# All buiseness logic in serice objects
class CreateUserService
  extend  Dry::Initializer
  include Dry::Monads::Result::Mixin
  option :user_name
  option :email
  ...
    
  # also you can use monads using 
  # https://dry-rb.org/gems/dry-monads/do-notation/
  def call
    write_user.bind do |user_id, email|
      send_email(email).bind do 
        do_some_logic.bind
      end
    end
  end
  
  private
  
  # each service return only Success or failure
  # which why we always render success or error and dont fail after raise error
  def write_user
    WriteUserInDbSerice.new(@user_id).call
  end
  
  def send_email
    SendEmailSerice.new(@user_id).call
  end
  
  def do_some_logic
    v = do_smthng
    Succcess(v)
  rescue StandardError => e
    Failure("Error in logic: #{v}, exception: #{e}")
  end
end

some_query.rb

# project/app/services/some_query.rb
# In query objects only selects
class CreateUserQuery
    extend  Dry::Initializer
  ....
end

users_controllers.rb

# project/app/controllers/users_controllers.rb
class UsersController < ApiController
  # maybe we should call some validators from project/app/validators/*
  # and in that validators validate params using dry-validate
  def index
      params.require(:consumer)
      params.require(:configuration)
      params.require(:custom)
      params.permit!

      result = CreateUserService.new(user_name: params[:user_name],
                                     email: params[:email]).call

      render_response serializer: ::SomeSerializer, result: result
    end
end