How to Extract a Value from microservice returned Observable in NestJS? - nestjs

Question

I am trying to implement NestJS Microservice to Validate my Bearer Token:
Whenever I get TCP response from Microservice which decides whether token is valid or not, it return Observable object, I am unable to extract the response from that Observable, please help me. Not getting proper way to extract the value from Observable in Nestjs, already tried lastValueFrom from RXJS
Here is the Controller to Make a call to Microservice(consumer/caller of microservice):
app.controller.ts
import { Body, Controller, Get, Post } from '#nestjs/common';
import { AppService } from './app.service';
import { PayloadDTO} from './payload.dto';
#Controller()
export class AppController {
constructor(private readonly appService: AppService) {}
#Get()
getHello(): string {
return this.appService.getHello();
}
#Post()
createUserData(#Body() payload: PayloadDTO) {
const token = header.authorization.replace('Bearer ', '')
const isValidToken = this.appService.validateToken(token);
}
if(isValidToken) {
this.appService.CreateRecord(Payload : PayloadDTO)
} else {
//Throw New UnathorizedException
}
}
app.service.ts
import { Inject, Injectable } from '#nestjs/common';
import { ClientProxy } from '#nestjs/microservices';
import { PayloadDTO } from './payload.dto';
#Injectable()
export class AppService {
constructor(
#Inject('COMMUNICATION') private readonly commClient: ClientProxy
) {}
// service method to call and validate token
validateToken(token: String) {
//calling microservice by sending token
const checkToken: Observable = this.commClient.send({cmd:'validate_token'},token);
//Unable to extract value from Observable here, it is returning observable object
return extractedResponse;
}
// service method to create record
createRecord(payload: PayloadDTO) {
//code related to creating new Record
}
}
app.controller.ts - Microservice Project
import { Controller, Get } from '#nestjs/common';
import { MessagePattern } from '#nestjs/microservices';
import { AppService } from './app.service';
#Controller()
export class AppController {
constructor(private readonly appService: AppService) {}
#MessagePattern({ cmd: 'validate_token' })
validateToken() {
return this.appService.checkToken();
}
}

Answer 1

Finally I got the answer on my own:
In Microservice Consumer/Caller app.controller.ts I forgot to use await before calling this.appService.validateToke(token)
#Post()
async createUserData(#Body() payload: PayloadDTO) {
const token = header.authorization.replace('Bearer ', '')
const isValidToken = await this.appService.validateToken(token);
}
To convert/extract value from Observable:
In app.service.ts (consumer/caller of microservice) :
use async before validateToken
use await lastValueFrom(checkToken)
return resp
// service method to call and validate token
async validateToken(token: String) {
//calling microservice by sending token
const checkToken = this.commClient.send({cmd:'validate_token'},token);
const resp = await lastValueFrom(checkToken);
reutn resp;
}