Error while trying to call detectintent api in nodejs-Dialogflow CX - node.js

Question

I am trying to send a request to DetectIntent API from webhook - Dialog Flow CX . I downloaded service-key in GCP and stored in serviceaccount.json file .I created .env file and stored all the values from serviceaccount file to .env file.I get error when I run "node index.js"
Error:"IAM permission 'dialogflow.sessions.detectIntent' on 'projects/dialogflowcx-340818,/agent' denied.",
I went through related stackoverflow posts where they suggested to set GOOGLE_APPLICATION_CREDENTIALS .I tried that as well.Still I get the same error.
I tried :
process.env.GOOGLE_APPLICATION_CREDENTIALS="/Users/suchitranagarajan/Desktop/nodeproject/detectintent/service-account.json"
Also,I tried to set
export GOOGLE_APPLICATION_CREDENTIALS="/Users/suchitranagarajan/Desktop/nodeproject/detectintent/service-account.json"
Please find the code below:
const dialogflow = require('#google-cloud/dialogflow');
test=require('dotenv').config();
const express = require('express');
const path = require("path");
process.env.GOOGLE_APPLICATION_CREDENTIALS="/Users/suchitranagarajan/Desktop/nodeproject/detectintent/service-account.json"
const PROJECTID = process.env.project_id;
const location=process.env.location
const agentid=process.env.agentid
const CONFIGURATION = {
credentials: {
private_key: process.env.private_key,
client_email: process.env.client_email
}
}
const sessionClient = new dialogflow.SessionsClient();
const detectIntent = async (languageCode, queryText, sessionId) => {
let sessionPath = sessionClient.projectLocationAgentSessionPath(PROJECTID,location,agentid,sessionId);
// The text query request.
let request = {
session: sessionPath,
queryInput: {
text: {
// The query to send to the dialogflow agent
text: queryText,
// The language used by the client (en-US)
languageCode: languageCode,
},
},
};
// Send request and log result
const responses = await sessionClient.detectIntent(request);
console.log(responses);
const result = responses[0].queryResult;
console.log(result);
return {
response: result.fulfillmentText
};
}
detectIntent("en", "hello", "abcd1234");
// Start the webapp
const webApp = express();
// Webapp settings
webApp.use(express.urlencoded({
extended: true
}));
webApp.use(express.json());
// Server Port
const PORT = process.env.PORT || 5000;
// Home route
webApp.get('/', (req, res) => {
res.send(`Hello World.!`);
});
// Dialogflow route
webApp.post('/dialogflow', async (req, res) => {
let languageCode = req.body.languageCode;
let queryText = req.body.queryText;
let sessionId = req.body.sessionId;
let responseData = await detectIntent(languageCode, queryText, sessionId);
res.send(responseData.response);
});
// Start the server
webApp.listen(PORT, () => {
console.log(`Server is up and running at ${PORT}`);
});
Please find .env file below:
type= service_account,
project_id=xxx,
private_key_id=xxx,
private_key=xxx","client_email": "xxx","client_id": "xxx","auth_uri": "xxx,
token_uri=xxx,
auth_provider_x509_cert_url= xxx,
client_x509_cert_url=xxx
location=xxx
agentid=xxx