Firebase Cloud Functions - Change Firestore settings

Question

I'm using Firebase Cloud Function and since recently, the logs show me this message:

The behavior for Date objects stored in Firestore is going to change AND YOUR APP MAY BREAK. To hide this warning and ensure your app does not break, you need to add the following code to your app before calling any other Cloud Firestore methods:

const firestore = new Firestore();
const settings = {/* your settings... */ timestampsInSnapshots: true};
firestore.settings(settings);

The problem is that when I add that piece of code into my functions file, I get this error every time I try to deploy:

ReferenceError: Firestore is not defined

Can somebody help me find what could be wrong?

(Do I need to add a Firestore dependence in the package.json file? Even if I don't need to do it whereas I already use the Firestore features?)

Thank you

Answer 1

This should do the work:

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

const firestore = admin.firestore();

// Add this magical line of code:
firestore.settings({ timestampsInSnapshots: true }); 

Then in your function use the firestore object directly:

firestore.doc(`/mycollection/${id}`).set({ it: 'works' })

UPDATE as of March, 2019:

If using firebase-admin version 7.0.0 or above, you no longer need this fix.

In Version 7.0.0 - January 31, 2019 of firebase-admin there were some breaking changes introduced:

BREAKING: The timestampsInSnapshots default has changed to true.

The timestampsInSnapshots setting is now enabled by default so timestamp fields read from a DocumentSnapshot will be returned as Timestamp objects instead of Date. Any code expecting to receive a Date object must be updated.

What's more, as stated in the official docs, timestampsInSnapshots is going to be removed in a future release so make sure to remove it altogether.

Answer 2

The advice you're getting in the logs is intended for people using the Firestore node SDK directly. However, when you write Firestore triggers through Cloud Functions, the Admin SDK is initialized automatically, which in turn initializes the Firestore SDK automatically. So, you don't have an opportunity to initialize it yourself.

Until the Firestore SDK is fully finalized, all you can do is make sure that your usage of dates is consistent with the future, fully released Firestore SDK. This means you should use Timestamp objects when reading dates out of snapshots. If you're doing that, you can ignore this warning message.