ddd-es-node

ddd-es-node

DDD and Event Sourcing primitives for nodejs

Install

npm install ddd-es-node --save

Usage

Define events.

import { EntityEvent } from "ddd-es-node";

export class OrderCancelledEvent extends EntityEvent {
}

Create domain entities.

import { Entity } from "ddd-es-node";
import { OrderCancelledEvent } from "./events";

export class Order extends Entity {
  private cancelled : boolean;
  constructor(id) {
    super(id, (self, event) => {
      if(event instanceof OrderCancelledEvent) {
        this.cancelled = true;
      }
    });
  }
  public cancel() {
    if(this.cancelled) {
      throw new Error('Order already cancelled');
    } else {
      this.dispatch(new OrderCancelledEvent());
    }
  }
}

Load entities and execute commands.

import { entityRepository } from "ddd-es-node";
import { Order } from "./orders";

export const cancelOrder = (id) : void => {
  return entityRepository
      .load(Order, id)
      .then((order : Order) => order.cancel());
};

Add event subscribers.

import { eventBus, EntityEvent } from "ddd-es-node";
import { OrderCancelledEvent } from "./events";

eventBus.subscribe((event : EntityEvent) => {
  if (event instanceof OrderCancelledEvent) {
    // do something
  }
}, { replay: true });