Home/ Questions/Q 5946119
In Process

The Archive Base Latest Questions

Editorial Team
  • 0
Asked: 2026-05-22T16:46:39+00:00

In Domain Driven Design (DDD), an Entity always has its own unique identity. In

  • 0

In Domain Driven Design (DDD), an Entity always has its own unique identity.

In my reading on DDD I have seen statements and examples that seem to mix the concepts of “unique identity” between Entities and Aggregate Roots. Depending on the example, they can imply that:

  • I only need one of the interfaces below.

or

  • I need both.

I would like to know which approach is “correct” as far as “Eric Evans type DDD” is concerned.

For example, let’s say your Entities implement this interface and return a GUID when this method is called:

public interface IEntity
{
   object IdThatIsUniqueForThisEntityObject { get; }
}

Do you need the one below too or not?

public interface IAggregateRoot
{
   object IdThatIsUniqueForThisAggregateRootObject { get; }
}

Does the Aggregate Root need to implement an interface like the one above so that it can represent its own unique ID (IdThatIsUniqueForThisAggregateRootObject) that is separate and different from its root Entity’s ID (IdThatIsUniqueForThisEntityObject)?

Or should the Aggregate Root just use the root Entity’s (IdThatIsUniqueForThisEntityObject) to represent the Unique ID of the Aggregate Root?

Share

Leave an answer

You must login to add an answer.

Need An Account,

1 Answer

  1. Editorial Team

    You only need the EntityId. There is no additional Aggregate Root Identity that is created. An aggregate root is an aggregate that is used to control access and organize objects as a single unit of database work. The aggregate does not confer any sort of “new” or additional identity for an object.

    An entity always has it’s unique entity identity and that should be sufficient. By definition, an operation that retrieves an entity which is an aggregate root also retrieves the aggregate in doing so. There is no concept of an entity which is sometimes just the standalone entity, and other times the aggregate root. So there is also no need for a concept of “Aggregate Root Identity” at all.

    • 0