net core-领域事件

参考：https://blog.csdn.net/qq_33649351/article/details/120067864

一. 定义领域通知接口

 public interface IDomainEvent : INotification
    {
    }

二.定义具体领域通知事件

public class OrderCreatedDomainEvent : IDomainEvent
    {
        public Order Order { get; private set; }
        public OrderCreatedDomainEvent(Order order)
        {
            this.Order = order;
        }
    }

三.在实体父类中增加对领域事件的处理

#region 领域事件的处理
        private List<IDomainEvent> _domainEvents;
        public IReadOnlyCollection<IDomainEvent> DomainEvents => _domainEvents?.AsReadOnly();

        public void AddDomainEvent(IDomainEvent eventItem)
        {
            _domainEvents = _domainEvents ?? new List<IDomainEvent>();
            _domainEvents.Add(eventItem);
        }

        public void RemoveDomainEvent(IDomainEvent eventItem)
        {
            _domainEvents?.Remove(eventItem);
        }

        public void ClearDomainEvents()
        {
            _domainEvents?.Clear();
        }
#endregion

四，在具体领域实体对象更新时增加相应的领域事件

public class Order : Entity<long>, IAggregateRoot
    {
        public string UserId { get; private set; }

        public string UserName { get; private set; }

        public Address Address { get; private set; }

        public int ItemCount { get; private set; }

        protected Order()
        { }

        public Order(string userId, string userName, int itemCount, Address address)
        {
            this.UserId = userId;
            this.UserName = userName;
            this.Address = address;
            this.ItemCount = itemCount;

            //添加OrderCreatedDomainEvent领域事件
            this.AddDomainEvent(new OrderCreatedDomainEvent(this));
        }
    }
}

五. EFContext 中实现领域事件的发送

#region IUnitOfWork
public async Task<bool> SaveEntitiesAsync(CancellationToken cancellationToken = default)
{
            var result = await base.SaveChangesAsync(cancellationToken);

            //实现领域事件的发送
            await _mediator.DispatchDomainEventsAsync(this);
            return true;
}
#endregion

static class MediatorExtension
{
        public static async Task DispatchDomainEventsAsync(this IMediator mediator, DbContext ctx)
        {
            var domainEntities = ctx.ChangeTracker
                .Entries<Entity>()
                .Where(x => x.Entity.DomainEvents != null && x.Entity.DomainEvents.Any());

            var domainEvents = domainEntities
                .SelectMany(x => x.Entity.DomainEvents)
                .ToList();

            domainEntities.ToList()
                .ForEach(entity => entity.Entity.ClearDomainEvents());

            foreach (var domainEvent in domainEvents)
                await mediator.Publish(domainEvent);
        }
}

待续。。