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Nest-MQTT

Description

A MQTT module for Nest.js. Compatible with emqtt.

Installation

⚠️ After version 0.2.0, nest-mqtt make a breaking change. User should add additional mqtt package manual.

$ npm install nest-mqtt mqtt --save

Usage

Import

Nest-mqtt will register as a global module.

You can import with configuration

// app.module.ts
import { Module } from '@nestjs/common';
import { MqttModule } from 'nest-mqtt';

@Module({
  imports: [MqttModule.forRoot(options)]
})
export class AppModule {}

or use async import method

// app.module.ts
import { Module } from '@nestjs/common';
import { MqttModule } from 'nest-mqtt';

@Module({
  imports: [MqttModule.forRootAsync({
    useFactory: () => options,
  })]
})
export class AppModule {}

Subscribe

You can define any subscriber or consumer in any provider. For example,

import { Injectable } from '@nestjs/common';
import { Subscribe, Payload, Topic } from 'nest-mqtt';

@Injectable()
export class TestService {
  @Subscribe('test')
  test() {
  
  }
  
  @Subscribe({
    topic: 'test2',
    transform: payload => payload.toString(),
  })
  test2() {
    
  }
}

Also, you can inject parameter with decorator:

import { Injectable } from '@nestjs/common';
import { Subscribe, Payload } from 'nest-mqtt';

@Injectable()
export class TestService {
  @Subscribe('test')
  test(@Payload() payload) {
    console.log(payload);
  }
}

Here are all supported parameter decorators:

Payload(transform?: (payload) => any)

Get the payload data of incoming message. You can pass in a transform function for converting.

Topic()

Get the topic of incoming message.

Packet()

Get the raw packet of incoming message.

Params()

Get the wildcard part of topic. It will return an array of string which extract from topic. For example:

When subscribe the topic "test/+/test/+" and incoming topic is "test/1/test/2", you will get the array ["1", "2"].

Publish

Nest-mqtt wrap some functions with Promise and provide a provider.

import { Inject, Injectable } from '@nestjs/common';
import { MqttService } from 'nest-mqtt';

@Injectable()
export class TestService {
  constructor(
    @Inject(MqttService) private readonly mqttService: MqttService,
  ) {}

  async testPublish() {
    this.mqttService.publish('topic', {
      foo: 'bar'
    });
  }

}

Emqtt Compatible

nest-mqtt support emq shared subscription

  • Global mode

Module options support queue and share property for globally converting all topic to shared topic except configured in subscription options.

// app.module.ts
import { Module } from '@nestjs/common';
import { MqttModule } from 'nest-mqtt';

@Module({
  imports: [MqttModule.forRoot({
    host: '127.0.0.1',
    queue: true,
    share: 'group1'
  })]
})
export class AppModule {}
  • Configure in Subscribe
import { Injectable } from '@nestjs/common';
import { Subscribe, Payload, Topic } from 'nest-mqtt';

@Injectable()
export class TestService {
  @Subscribe('test')
  test() {
  
  }
  
  @Subscribe({
    topic: 'test2',
    queue: true,
  })
  test2() {
    
  }
}

The priority of subscribe is higher than the global mode. If you want to specify a topic do not use the shared mode, set it as false in subscribe decorator.

Support

Nest-mqtt is an MIT-licensed open source project. It can grow thanks to the sponsors and support by the amazing backers. If you'd like to join them, please read more here.

Stay in touch

License

nest-mqtt is MIT licensed.