Ahmad Al-kheat Hamada92

Building Rich Domain Models in Rails

Abstract

Domain model is an effective tool for software development. It can be used to express really complex business logic, and to verify and validate the understanding of the domain among stakeholders. Building rich domain models in Rails is hard. Primarily, because of Active Record, which doesn't play well with the domain model approach.

One way to deal with this problem is to use an ORM implementing the data mapper pattern. Unfortunately, there is no production ready ORM doing that for Ruby. DataMapper 2 is going to be the first one.

Another way is to use Active Record just as a persistence mechanism and build a rich domain model on top of it. That's what I'm going to talk about here.

	require 'sidekiq/api'

	# 1. Clear retry set

	Sidekiq::RetrySet.new.clear

	# 2. Clear scheduled jobs

	Sidekiq::ScheduledSet.new.clear

	#!/bin/bash
	set -o errexit
	clear

	# Set versions. Check http://openresty.org for latest version and bundled version of nginx.
	OPENRESTY_VERSION=1.9.3.1
	NGINX_VERSION=1.9.3
	OPENSSL_VERSION=1.0.2d

	# Install some pre-requisites

	module Storage
	module Models
	class Brand < ActiveRecord::Base; end
	end
	end

	# This probably isn't a good thing to want to do, but it came up for me,
	# so in the spirit of helping others with weird problems (and because this
	# seems to be documented almost nowhere):

	after_save do

	if some_failing_condition
	errors.add(:something, "some failure happened.")
	raise ActiveRecord::RecordInvalid.new(self)
	end