Firestore and CORS

[Arnaud Deman]

Hi,

I am trying to use firestore (which is new for me) in an Angular 5 app but I am facing a CORS error and I am a little bit stucked.

A service in my Angular App makes an http post to a firebase function written in nodejs and epress to make a record into firestore.

I do not have a very thorough knowledge of cors and this is probably one of the sources of my problem.

The function use express and this is the relevant code :

initialization of firebase

import * as functions from 'firebase-functions';

const admin = require('firebase-admin');

admin.initializeApp(functions.config().firebase);

Initialization of express :

import * as express from 'express';

import * as cors from 'cors';

const twitterApp = express();

twitterApp.use(cors({ origin: true }));

The code in the express post handler,  used  to make the record into firestore :

private _db = admin.firestore();

...

post(req, res, next) {

...

const docRef = this._db.collection('tweet').doc(postedTweetVO.tweetId);

return docRef.set(postedTweetVO).then((registeredTweet) => {

...

}).catch(error => {

...

});

And this is the error in the browser where the Angular app is executed :

us-central1-corpussystem.cloudfunctions.net/twitter/twt:1 POST https://us-central1-corpussystem.cloudfunctions.net/twitter/twt 500 ()

admin-document:1 Failed to load https://us-central1-corpussystem.cloudfunctions.net/twitter/twt: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://localhost:4200' is therefore not allowed access. The response had HTTP status code 500.

If I change the few lines of code above to make the record into the realtime database instead  of firestore it works fine :

post(req, res, next) {

...

return admin.database().ref('/tweet').push(postedTweetVO).then((snapshot) => {

...

}).catch(error => {

...

})

I can interact with firestore from my laptop with nodejs scripts whihout any trouble.

I have subscribed the flame plan so it is probably not a problem of outbound netorking.

Thanks for your help,

regards,

Arnaud.

[Arnaud Deman]

Hi,

I found the problem, and the CORS error message was not relevant.

The problem was due to the fact I tryed to write a Object and not a plain javascript object and because of that  the function crashed.

I replaced :

const postedTweetVO = new PostedTweetVO();

postedTweetVO.userId = data.user.id_str;

postedTweetVO.tweetId = data.id_str;

postedTweetVO.timestamp = timestamp;

const docRef = this._db.collection('tweet').doc(postedTweetVO.tweetId);

return docRef.set(postedTweetVO).then((registeredTweet) => { (...)

By :

const postedTweetVO = {

userId: data.user.id_str,

tweetId: data.id_str,

timestamp: timestamp

};

const docRef = this._db.collection('tweet').doc(postedTweetVO.tweetId);

return docRef.set(postedTweetVO).then((registeredTweet) => { (...)

Regards,

Arnaud.