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

First thing first, don't get to hung up on it - its easy to over engineer by creating unnecessary service classes etc. Less code is good. Check out the original source material, and the code in either Java or C#.

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

It can if required. For example my (java) class annotated with @Entity can also be annotated with @Configurable and have a session/other classes injected into it. That is the point - to encapsulate all necessary business logic and expose a clear simple api located on one Domain class.

2) Should a Repository be aware of Services in the domain?

No. But the opposite is likely, a Service would use a repository.

Services are used when more than one domain object/entity/root aggregate is utilized. So assuming a TAG is a separate entity, this would be fine :

$articleService->addTag($article, TagEntity); 

However if Tag is anot another root aggregate, you could just do

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

And article itself does the save (without any other calls) by having a repository/dao injected inside it.