How to get data from Firestore in Cloud Function? - firebase

Question

I need to know what I'm doing wrong here?
I'm calling this function from Flutter. The call back is getting done correctly and the first & second prints are coming in the "log" on Firbase. But getting undefined from the "Firestore"!!
This is the code in the Cloud Function:
var functions = require("firebase-functions");
let admin = require('firebase-admin');
admin.initializeApp(functions.config().firebase);
admin.firestore().settings({ timestampsInSnapshots: true });
exports.storeContact5 = functions.https.onCall((data, context) => {
// First print is working fine
console.log('test');
var recieverId = 'WqHxLoYvRxR9UK8sFJZ9WxTOIE32';
const check = admin.firestore().collection('users').doc(recieverId).get();
check.then(testValue => {
console.log(testValue.data.nickname);
return true;
}).catch(err => {
console.log('Error getting document', err);
});
console.log('test2');
// Return to flutter App (Working fine)
return {
repeat_message: 'ok!'
}
});
Screenshot for Firebase Log

Answer 1

You should do testValue.data().nickname and not testValue.data.nickname, see https://firebase.google.com/docs/firestore/query-data/get-data#get_a_document and https://firebase.google.com/docs/reference/js/firebase.firestore.DocumentSnapshot#data.
Also, you should return a result only once and you should not return outside of the .then() if you want to return the result of the asynchronous operation.
In addition, see here how to handle errors: https://firebase.google.com/docs/functions/callable#handle_errors
So you may do as follows:
exports.storeContact5 = functions.https.onCall((data, context) => {
// First print is working fine
console.log('test');
var recieverId = 'WqHxLoYvRxR9UK8sFJZ9WxTOIE32';
const check = admin.firestore().collection('users').doc(recieverId).get();
return check.then(testValue => {
console.log(testValue.data().nickname);
return {repeat_message: 'ok!'};
}).catch(err => {
console.log('Error getting document', err);
throw new functions.https.HttpsError('Error getting document', err);
});
});
I would suggest you watch the videos from the official series: https://firebase.google.com/docs/functions/video-series/, in particular the ones titled "Learn JavaScript Promises"