Version: v2

Internal Error Handling

To handle any internal error that might occur on pubsub side, the method handleError can be declared either in Subscriber Object or in SubscriptionService.

If the error handler is provided at Subscriber object level then it would override the error handler provided at SubscriptionService level.

Subscriber handleError Examples#

Typescript subscription example#

/pubsub/subscriptions/simple.topic.name.console-log.sub.ts

import { SubscriberObject, Message } from "@honestfoodcompany/pubsub";

export default: SubscriberObject = {
  topicName: 'simple.topic',
  subscriptionName: 'simple.topic.console-log.sub',
  description: 'Will console log messages published on test.topic',

  handleMessage: function(message: Message): void {
    console.log(this.subscriptionName, 'received message');
    console.log(message.data.toString());
    message.ack();
  },

  handleError: function(error: Error): void {
    // internal error handling logic for subscriber
    console.error(error);
    // Close DB connections/etc here
    process.exit(1);
  }
};

Javascript subscription example#

/pubsub/subscriptions/simple.topic.name.sub.js

exports.default = {
  topicName: 'test.topic',
  subscriptionName: 'test.topic.sub',
  description: 'Will console log messages published on test.topic',

  handleMessage: function (message) {
    console.log(this.subscriptionName, 'received message');
    console.log(message.data.toString());
    message.ack();
  },
  handleError: function (error) {
    // internal error handling logic for subscriber
    console.error(error);
    // Close DB connections/etc here
    process.exit(1);
  },
};

SubscriptionService handleError Examples#

You can also setup a global error handler that will act as the default for all subscriptions, this though also receives the subscription metadat for which the error happens.

Typescript subscription example#

/pubsub/subscription.service.ts

import { SubscriptionService, SubscriberOptions, SubscriberMetadata } from '@honestfoodcompany/pubsub';

export default class SubscriptionService extends PubSub.SubscriptionService {
  static subscribers = [
    //...
  ];

  static defaultSubscriberOptions: SubscriberOptions = {};

  static async init(): Promise<void> {}

  static handleError(error: Error, metadata: SubscriberMetadata): void {
    // global default error handling logic for all subscribers
    console.error({err, metadata}, 'Default error handler');
    // Close DB connections/etc here
    process.exit(1);
  }
}

Javascript subscription example#

/pubsub/subscription.service.js

const PubSub = require('@honestfoodcompany/pubsub');

class SubscriptionService extends PubSub.SubscriptionService {}

SubscriptionService.subscribers = [];

SubscriptionService.defaultSubscriberOptions = {};

SubscriptionService.init = () => {};

SubscriptionService.handleError = (error, metadata) => {
  // global default error handling logic for all subscribers
  console.error({err, metadata}, 'Default error handler');
  // Close DB connections/etc here
  process.exit(1);
};

exports.default = SubscriptionService;