Class AggregateRoot<T>Abstract

Base class for Aggregate Roots in Domain-Driven Design.

An Aggregate Root is the entry point to an aggregate, which is a cluster of domain objects that can be treated as a single unit. The Aggregate Root ensures the consistency of changes within the aggregate boundary and manages domain events.

Example

class Order extends AggregateRoot<'Order'> {
  constructor(id: EntityId<'Order'>, private items: OrderItem[]) {
    super(id, new Date(), new Date());
  }

  addItem(item: OrderItem): void {
    this.items.push(item);
    this.record({ occurredAt: new Date(), orderId: this.id.value, itemId: item.id });
    this.touch();
  }

  checkout(): void {
    // Business logic...
    this.record({ occurredAt: new Date(), orderId: this.id.value });
  }
}

// Later, publish events:
const events = order.pullDomainEvents();
await eventBus.publish(events);

Type Parameters

  • T extends string

    Phantom type representing the aggregate type (e.g., 'User', 'Order')

Hierarchy (View Summary)

Accessors

id createdAt updatedAt

Constructors

constructor

Methods

record pullDomainEvents hasDomainEvents touch equals

Accessors

id

createdAt

  • get createdAt(): Date

    Gets the timestamp when this entity was created.

    Returns Date

updatedAt

  • get updatedAt(): Date

    Gets the timestamp when this entity was last updated.

    Returns Date

Constructors

Protectedconstructor

Methods

Protectedrecord

  • record(event: DomainEvent): void
    Protected

    Records a domain event that occurred within this aggregate. Events are stored internally and can be retrieved later for publishing.

    Parameters

    Returns void

    Example

    this.record({
      occurredAt: new Date(),
      userId: this.id.value,
      email: 'user@example.com'
    });

pullDomainEvents

  • pullDomainEvents(): DomainEvent[]

    Retrieves and clears all domain events recorded by this aggregate. This is typically called after the aggregate is persisted, to publish the events.

    Returns DomainEvent[]

    An array of domain events

    Example

    await repository.save(order);
    const events = order.pullDomainEvents();
    await eventBus.publish(events);

hasDomainEvents

  • hasDomainEvents(): boolean

    Checks if this aggregate has any recorded domain events.

    Returns boolean

    true if there are pending domain events, false otherwise

Protectedtouch

  • touch(): void
    Protected

    Updates the updatedAt timestamp to the current time. Should be called whenever the entity's state changes.

    Returns void

equals

  • equals(other: Entity<T>): boolean

    Compares this entity with another for equality based on identity. Two entities are equal if they have the same ID and are of the same type.

    Parameters

    • other: Entity<T>

      The other entity to compare with

    Returns boolean

    true if the entities are equal, false otherwise

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