@nest-firebase/pubsub v2.2.1

@nest-firebase/pubsub

Description

This module provides @OnMessage() decorator to handle messages based on attributes

Motivation

At @skore-io we're building an event-driven architecture using firebase functions, which means that we're heavily using pubsub to emmit and receive events.

Unfortunately we can't filter messages before it arrives at service, so we've to do this work on each message that invokes a function. The steps we do always is: create nest instance, check message.attributes.type or message.attributes.action.

To facilitate this steps, we developed this library.

Usage

Install

npm install @nest-firebase/pubsub

Import

Import and add NestFirebaseModule to the imports section of the module you wish to implement.

import { PubsubModule } from '@nest-firebase/pubsub';
import { Module } from '@nestjs/common';

@Module({
  imports: [PubsubModule]
})
export class AppModule { }

Filtering messages

The PubsubModule exposes @OnMessage() decorator to filter your messages

To filter messages from topic events with type io.skore.events.user and action created:

import { Injectable } from '@nestjs/common'
import { OnMessage } from '@nest-firebase/pubsub';
import { Message } from 'firebase-functions/lib/providers/pubsub'

@Injectable()
export class UserCreatedListener {
  @OnMessage({
    topic: 'events',
    type: 'io.skore.events.user',
    action: 'created'
  })
  async onUserCreatedMessage(message: Message): void {}
}

type and action accept regular expressions, let's suppose you want to listen for all type which contains io.skore and action which is created or updated, so do the following:

import { Injectable } from '@nestjs/common'
import { OnMessage } from '@nest-firebase/pubsub';
import { Message } from 'firebase-functions/lib/providers/pubsub'

@Injectable()
export class UserCreatedListener {
  @OnMessage({
    topic: 'events',
    type: 'io.skore.*',
    action: 'created|updated'
  })
  async onUserCreatedMessage(message: Message): void {}
}

Exporting firebase function

To use firebase functions you must export your functions in an index.ts file, so do the following:

import { Pubsub } from '@nest-firebase/pubsub';

export const onEvent = Pubsub.topic('events', AppModule)

Where events is your pubsub topic and AppModule is your nest module which imports PubsubModule