DDD and Domain Events

One of the core features of Silverback is the ability to publish the domain events as part of the DbContext save changes transaction in order to guarantee consistency.

The Silverback.Core.Model package contains a sample implementation of a DomainEntity but you can also implement you own type.

Important

In case of a custom implementation the only constraint is that you must implement the IMessagesSource interface in order for Silverback to be able to access the associated events.

The DomainEntity.AddEvent method adds the domain event to the events collection, to be published when the entity is saved. To enable this mechanism we just need to override the various SaveChanges methods to plug-in the DbContextEventsPublisher contained in the Silverback.Core.EntityFrameworkCore package.

• Sample Entity
• DbContext

using Silverback.Domain;

namespace Sample
{
    public class Basket : DomainEntity, IAggregateRoot
    {
        private readonly List<BasketItem> _items = new List<BasketItem>();

        private Basket()
        {
        }

        public Basket(Guid userId)
        {
            UserId = userId;
            Created = DateTime.UtcNow;
        }

        [Key]
        public int Id { get; private set; }
        public IEnumerable<BasketItem> Items => _items.AsReadOnly();
        public Guid UserId { get; private set; }
        public DateTime Created { get; private set; }
        public DateTime? CheckoutDate { get; private set; }

        public void Checkout()
        {
            CheckoutDate = DateTime.UtcNow;

            AddEvent<BasketCheckoutEvent>();
        }
    }
}