aspnetboilerplate EventCloud example - design pattern

Question

in this tutorial about the EventCloud example app: https://aspnetboilerplate.com/Pages/Documents/Articles/Developing-MultiTenant-SaaS-ASP.NET-CORE-Angular/index.html

the text states: the creation of a new entity must be done using the static method "Create" in the "Event" class (not using "new Entity(....)")

1) so my first question is: which design pattern is this? Factory? Builder? other?

[Table("AppEvents")]
public class Event : FullAuditedEntity<Guid>, IMustHaveTenant
{
 ......
 ....
 ...
 /// <summary>
 /// We don't make constructor public and forcing to create events using <see cref="Create"/> method.
 /// But constructor can not be private since it's used by EntityFramework.
 /// Thats why we did it protected.
 /// </summary>
 protected Event()
 {

 }

 public static Event Create(int tenantId, string title, DateTime date, string description = null, int maxRegistrationCount = 0)
 {
    var @event = new Event
    {
        Id = Guid.NewGuid(),
        TenantId = tenantId,
        Title = title,
        Description = description,
        MaxRegistrationCount = maxRegistrationCount
    };

    @event.SetDate(date);

    @event.Registrations = new Collection<EventRegistration>();

   return @event;
 }

 ....
 ...

2) the second question:

than the article says...

Event Manager .... All Event operations should be executed using this class... (EventManager)

ok, the CreateAsync method call the repository insert method, is the static "Event.Create" internaly called from the repository insert method? if yes, could you indicate me the point in the abp source code? or is it an internal matter of EntityFramework?

public class EventManager : IEventManager
{
 ......
 ....
 ..
 public async Task CreateAsync(Event @event)
 {
     await _eventRepository.InsertAsync(@event);
 }

Answer 1

Here are my answers:

1-) Event is being created with a static factory method. There are 2 ways to create an entity in Domain Driven Design.

1. Creating with static factory methods: It's a convenient way of creating business entities. And this method is being used in EventCloud. The only downside of this method is it's static! If your entity is holding state it's not good for testability. But there are 3 advantages of this approach;
   1. They have names: for example Event.CreatePublicEvent(), Create.PrivateEvent()
   2. They can cache: You can cache them in a private static HashSet or Dictionary.
   3. They can subtype.

2. Creating with a constructor: If you have only one constructor then creating an object through its public constructor is the most convenient approach in Domain Driven Design. As long as you make parameterless constructor protected or private. Besides, an entity should be responsible for its own data integrity and validity so you have to set all business related public properties as private setter and you should allow them to change through public methods.

   Further information, see https://www.yegor256.com/2017/11/14/static-factory-methods.html

---

2-) EventManager is a domain service that is used for business logic. And Event.Create() is being used in the EventAppService class. Click here to see where exactly is being executed. Even Event.Create() method consists of a single line of code but it's open for extension.

I hope that will be useful ;)

Happy coding...