First microservice handler

For our first microservice handler, let’s convert the UserController index method into a microservice handler. To do this, we copy the method and make a few simple modifications. Instead of annotating the method with Get, we will use MessagePattern.

@Controller()
export class UserController {

    @Get('users')
    public async index(@Res() res) {
        const users = await this.userService.findAll();
        return res.status(HttpStatus.OK).json(users);
    }

    @MessagePattern({cmd: 'users.index'})
    public async rpcIndex() {
        const users = await this.userService.findAll();
        return users;
    }
}

A message pattern provides Nest.js the means for determining which microservice handler to execute. The pattern can be a simple string or a complex object. When a new microservice message is sent, Nest.js will search through all registered microservice handlers to find the handler that matches the message pattern exactly...