cqrs-toolkit

a toolkit that eases managing cqrs events and commands

Features:

• Event Bus:
• Command Bus:
• ICommand/IEvent interface

Handling multiple events with v2

Pass multiple event classes to EventHandlerV2 to route them to the same handler:

@EventHandlerV2([OrderCreated, OrderCancelled])
class OrderEventHandler implements IEventHandler<IEvent> {
  async handle(event: IEvent) {
    if (event instanceof OrderCreated) {
      // Handle creation.
    } else if (event instanceof OrderCancelled) {
      // Handle cancellation.
    }
  }
}

Passing a single event remains supported: @EventHandlerV2(OrderCreated).

Handling one event with multiple v2 handlers

Decorate multiple handler classes with the same event to fan out each dispatch:

@EventHandlerV2(OrderCreated)
class SendConfirmation implements IEventHandler<OrderCreated> {
  async handle(event: OrderCreated) {
    return `confirmation:${event.name}`;
  }
}

@EventHandlerV2(OrderCreated)
class UpdateReporting implements IEventHandler<OrderCreated> {
  async handle(event: OrderCreated) {
    return `reporting:${event.name}`;
  }
}

const results = await eventBus.handle<string>(new OrderCreated());

Handlers run concurrently. results contains their resolved values in registration order. If any handler rejects, the dispatch rejects after all handlers have already been started. Dispatching an event with no registered handlers also rejects.