How to raise event in CQRS pattern with identity for user table

Question

I want to raise events when various identity events occur (for example, adding a user and using the userManager). I do this well for other entities but since the user entity inherits from IdentityUser I need some guidance on how to use it.

For example, one of the entities that I can use baseEntity well:

 public class Vehicle : BaseEntity
 {
  ...
 }

BaseEntity:

public abstract class BaseEntity
{
    public string Id { get; set; }

    private readonly List<BaseEvent> _domainEvents = new();

    [NotMapped]
    public IReadOnlyCollection<BaseEvent> DomainEvents => _domainEvents.AsReadOnly();

    public void AddDomainEvent(BaseEvent domainEvent)
    {
        _domainEvents.Add(domainEvent);
    }

    public void RemoveDomainEvent(BaseEvent domainEvent)
    {
        _domainEvents.Remove(domainEvent);
    }

    public void ClearDomainEvents()
    {
        _domainEvents.Clear();
    }
    
}

But in the ApplicationUser entity, I cannot use this base Entity to implement events because the applicationUser class inherits from the IdentityUser class!

    public class ApplicationUser : IdentityUser
    {

        public string FirstName { get; set; }
        public string LastName { get; set; }
        public string FatherName { get; set; }

    }

How can I use both IdentityUser and BaseEntity for events to occur in the ApplicationUser class?

Answer 1

You can Seperate them like this: An Interface For Entities that Have Id

public interface BaseId<T> where T : class
{
    public T Id { get; set; }
}

An Interface For Enntity With Domain Events

public interface EntityWithDomainEvent
{
    IReadOnlyCollection<BaseEvent> DomainEvents { get; }
    void AddDomainEvent(BaseEvent domainEvent);
    void RemoveDomainEvent(BaseEvent domainEvent);
    void ClearDomainEvents();
}

An Abstract Class To Wrap it all for other entities to get inherit from

public abstract class BaseEntity : BaseId<string>,EntityWithDomainEvent
{
    public string Id { get; set; }
    private readonly List<BaseEvent> _domainEvents = new();
    public IReadOnlyCollection<BaseEvent> DomainEvents => _domainEvents.AsReadOnly();

    public void AddDomainEvent(BaseEvent domainEvent)
    {
        _domainEvents.Add(domainEvent);
    }

    public void RemoveDomainEvent(BaseEvent domainEvent)
    {
        _domainEvents.Remove(domainEvent);
    }

    public void ClearDomainEvents()
    {
        _domainEvents.Clear();
    }
}

And Finally Your ApplicationUser

public class ApplicationUser : IdentityUser,EntityWithDomainEvent
{

    public string FirstName { get; set; }
    public string LastName { get; set; }
    public string FatherName { get; set; }
    private readonly List<BaseEvent> _domainEvents = new();
    public IReadOnlyCollection<BaseEvent> DomainEvents => _domainEvents.AsReadOnly();

    public void AddDomainEvent(BaseEvent domainEvent)
    {
        _domainEvents.Add(domainEvent);
    }

    public void RemoveDomainEvent(BaseEvent domainEvent)
    {
        _domainEvents.Remove(domainEvent);
    }

    public void ClearDomainEvents()
    {
        _domainEvents.Clear();
    }

}