Firebase cloud function cannot read property 'displayName' of undefined

I want to create user profile in realtime database after google login in my android app.
So, I have tried this code in cloud function to do it.

const functions = require(‘firebase-functions’);
const admin = require(‘firebase-admin’);


exports.AddAccount = functions.auth.user().onCreate(event => {

const user =;
var userObject = {
	displayName : user.displayName,
	email :,
	photoUrl : user.photoURL,
	createdOn : user.metadata.createdAt
admin.database().ref('users/' + user.uid).set(userObject);


after deploying this code i tested in my app.
and it is showing error.

    TypeError: Cannot read property 'displayName' of undefined
    at exports.AddAccount.functions.auth.user.onCreate.event (/srv/index.js:10:22)
    at cloudFunction (/srv/node_modules/firebase-functions/lib/cloud-functions.js:131:23)
    at /worker/worker.js:825:24
    at <anonymous>
    at process._tickDomainCallback (internal/process/next_tick.js:229:7)

please help me to fix this error