如何使用nestjs redis微服务？

Question

I am learning nestjs microservice,

What command can I use?

const pattern = { cmd: 'get' };
this.client.send<any>(pattern, data)

And how can I receive data from redis?

constructor(private readonly appService: AppService) {}
      @Client({
        transport: Transport.REDIS,
        options: {
          url: 'redis://127.0.0.1:6379',
        },
      })
      client: ClientProxy;

      @Get()
      getHello(): any {
        const pattern = { cmd: 'get foo' };  //Please write sample code here in document
        const data = '';
        return this.client.send<any>(pattern, data);
      }

Answer 1

There are two sides you need to separate. They can be part of one nest.js application (eg hybrid application ) or be in several different nest.js applications:

Client

The client broadcasts messages on a topic/pattern and receives a response from the receiver(s) of the broadcasted message.

First, you have to connect your client. You can do that in onModuleInit . In this example, ProductService broadcasts a message when a new product entity is created.

@Injectable()
export class ProductService implements OnModuleInit {

  @Client({
    transport: Transport.REDIS,
    options: {
      url: 'redis://localhost:6379',
    },
  })
  private client: ClientRedis;

  async onModuleInit() {
    // Connect your client to the redis server on startup.
    await this.client.connect();
  }

  async createProduct() {
    const newProduct = await this.productRepository.createNewProduct();
    // Send data to all listening to product_created
    const response = await this.client.send({ type: 'product_created' }, newProduct).toPromise();
    return response;
  }
}

Keep in mind, that this.client.send returns an Observable . This means, nothing will happen until you subscribe to it (which you can implicitly do by calling toPromise() ).

Pattern Handler

The pattern handler consumes messages and sends a response back to the client.

@Controller()
export class NewsletterController {

  @MessagePattern({ type: 'product_created' })
  informAboutNewProduct(newProduct: ProductEntity): string {
    await this.sendNewsletter(this.recipients, newProduct);
    return `Sent newsletter to ${this.recipients.length} customers`;
  }

Of course, a param handler could also be a client and therewith both receive and broadcast messages.