Domain Driven Design and IoC/Dependency Injection

Question

I\'m trying to apply now what I learned about DDD and I\'m a little bit confused about the flow of dependencies in the Domain model.

My questions are:

1. Shou

Answer 1

Should an Entity be aware of Factories, Repositories, Services in the domain?

An entity should never reference a repository or an application service. It is acceptable for entities to reference a factory if it uses it to create a constituent entity. It is also acceptable for an entity to have a dependency on a domain service if it uses that services for certain behavior.

Should a Repository be aware of Services in the domain?

Generally no. A repository should only be responsible for persistence.

Now, in case I want to add a relation with a new tag. What would be the better way to do it?

It depends on which layer you refer to. In a typical DDD architecture, you'd have both pieces of code. You'd have an article application service which encapsulates the domain and provides a granular method such as addTag where you'd pass an article ID and a tag ID. This method would retrieve the appropriate article and tag instances (if needed) and then:

$article->tags->add(TagEntity);
$articleRepository->save($article);

All outer layers depending on this domain would communicate with it through the application service.