What is this project?
DDD Rails Sample is a open-source project meant to be used as a start point, or an inspiration, for those who want to build Domain Driven Design applications in Ruby. As Rails is the most robust web framework in Ruby community we tried to use it in a way we could modularize the layers and decouple responsabilities. This project is the result of this efforts.
NOTE: This is NOT intended to be a definitive solution or a production ready project
- Ruby on Rails
- Active Record
- Object oriented programming following SOLID and Clean Code principles
- Domain Driven Design
- Repository Pattern
- CQRS (same database)
Nice to have in the future
- Include different Bounded Contexts
- Domain Events
- IoC Container or Service Locator
- Domain Notifications instead of raising exceptions
- Event Sourcing
- A simple front-end implementation
bundle install rails db:create rails db:migrate rails db:seed rails s
Different implementation versions
This project describes a two-phase implementation of the Repository pattern. The first implementation (version 1) is somewhat more pragmatic as the domain class itself inherit from Active Record. In the second one (version 2) we evolve this implementation in a way that our domain model became PORO classes, but that came with a cost as you can see in more details below.
In this version we treat te Persistence Model and Domain Model as the same thing. We use this in the first version because it is a way more simple, fast, and we can have take advantage from all benefits the ORM offers.
ORM + DDD dilemma: You can see more details about the tradeoffs and the risks of using the Persistence Model and Domain Models as the same thing or in a separated way in this SO answer.
The only problem with Active Record is that, different from other ORMs like SQLAlchemy (Python), Hibernate (Java), Entity Framework (.NET), you can't create an external class to map your domain model to the database. In Active Record your class MUST inherit from
ActiveRecord::Base in order to be persisted. This breaks (
... More details soon ...
Contributions are welcome