Injection of Dependencies Layers Application / Domain / Repository

Question

In an application using the concepts of DDD I am in doubt about who could inject (dependencies) in a certain class, if there is any standard for such.

This is the following between the Application, Domain and Repository layers.

1) A Customer Service (Application layer) that needs to inject user, I should inject User Applicationservice and call it User Service(Domain) or inject User Service directly into Customer Applicationservice?

2) In Clienteservice(Domain) I should inject Usuarioservice and call it Usuariorepository or I could inject Usuariorepository directly into Clienteservice?

I am worried about cyclic reference if I am injecting same level classes.

But tbm I think I should not inject the Repository of another Entity, because many times the repository methods have a rule in the service that should be called earlier.

Someone has already had this doubt, as you normally treat it?

Answer 1

At the beginning of your text you ask "Who" could inject the dependency into a class.

Dependency injection is the role of dependency injection infrastructure.

In a dependency graph - "A" depends on "B" - which in turn "B" depends on "C" - which in turn "C" depends on "D" - which in turn "D" depends on "E" - which in turn "E" depends on "F"

All these elements must be injected by the infrastructure. Starting it creation of F, then E, then D, C, B and finally A.

Circular reference is a problem, avoid it is necessary.

Boundaries Contexts help limit this dependency to Boundary Context. You’re probably not following this concept of DDD.