es cqrs.Interface.Event

@sclable/nestjs-libs / es-cqrs / Event

Interface: Event

Event interface

In order for the event-store to replay your events implement the Event interface and create a constructor according to EventConstructor, or for conveniency extend the DefaultEvent class:

constructor(
  public readonly aggregateId: string,
  public readonly aggregateType: string,
  public readonly revision: number,
  public readonly createdAt: Date,
  public readonly userId: string,
  public readonly data: {[key: string]: any}
)

It is recommended to define data as an interface with the event

Example:

import { Event } from '@sclable/es-cqrs'

interface EventData {
  accountName: string,
  email: string,
  birthday: Date,
}

export class AccountCreatedEvent implements Event {
  public constructor(
    public readonly aggregateId: string,
    public readonly aggregateType: string,
    public readonly revision: number,
    public readonly createdAt: Date,
    public readonly userId: string,
    public readonly data: EventData,
  ) {}
}

To use CustomEventOptions define that as the forth parameter

Example:

@EventForModule('MyModule')
export class AccountCreatedEvent implements Event {
  public constructor(
    public readonly aggregateId: string,
    public readonly aggregateType: string,
    public readonly revision: number,
    public readonly createdAt: Date,
    public readonly userId: string,
    public readonly data: EventData,
    public readonly custom: CustomEventOptions,
  ) {}
}

Or use it as a computed parameter

Example:

@EventForModule('MyModule')
export class AccountCreatedEvent implements Event {
  public constructor(
    public readonly aggregateId: string,
    public readonly aggregateType: string,
    public readonly revision: number,
    public readonly createdAt: Date,
    public readonly userId: string,
    public readonly data: EventData,
    public readonly custom: CustomEventOptions = { queueById: data.customId }
  ) {}
}

To handle these events implement the IEventHandler interface.

Example:

import { EventHandler, IEventHandler } from '@sclable/es-cqrs'
import { AccountCreatedEvent } from './events'

@EventHandler(AccountCreatedEvent)
export class AccountCreatedEventHandler implements IEventHandler<AccountCreatedEvent> {
  async handle(event: AccountCreatedEvent) {
    // do something (e.g. change DB, change view, emit to other type of listeners)
  }
}

Extends

• IEvent

Properties

aggregateId

aggregateId: string

Defined in

packages/es-cqrs/src/interfaces/event.ts:96

---

aggregateType

aggregateType: string

Defined in

packages/es-cqrs/src/interfaces/event.ts:97

---

createdAt

createdAt: Date

Defined in

packages/es-cqrs/src/interfaces/event.ts:99

---

customOptions?

optional customOptions: CustomEventOptions

Defined in

packages/es-cqrs/src/interfaces/event.ts:103

---

data

data: any

Defined in

packages/es-cqrs/src/interfaces/event.ts:102

---

revision

revision: number

Defined in

packages/es-cqrs/src/interfaces/event.ts:98

---

userId

userId: string

Defined in

packages/es-cqrs/src/interfaces/event.ts:100