How to add time to a firebase.database.ServerValue.TIMESTAMP

Question

I need to add time to a admin.database.ServerValue.TIMESTAMP and later retrieve it. But when I try to add additional time to theServerValue.TIMESTAMP I get an error:

getTime is not a function

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

const ten_secs = 10 * 1000; // 10 seconds
const daily_secs = 24 * 60 * 60 * 1000; // 24 hrs
const weekly_secs = 168 * 60 * 60 * 1000; // 1 week

exports.update = functions.https.onRequest((request, response) => {

    const currentTimeStamp = admin.database.ServerValue.TIMESTAMP;

    const updatedSecs = new Date(currentTimeStamp.getTime() + ten_secs); // should be saved in the db as milliseconds for later retrieve and calculations

    const updatedDay = new Date(currentTimeStamp.getTime() + daily_secs); // should be saved in the db as milliseconds for later retrieve and calculations

    const updatedWeek = new Date(currentTimeStamp.getTime() + weekly_secs); // should be saved in the db as milliseconds for later retrieve and calculations

    console.log("updatedSecs: " + updatedSecs + " | updatedDay: " + updatedDay + " | updatedWeek: " + updatedWeek);

    const ref = admin.database().ref('schedule').child("scheduleId_123").child("my_uid")

    ref.once('value', snapshot => {

        if (!snapshot.exists()) {

            return ref.set({ "updatedSecs": updatedSecs, "updatedDay": updatedDay, "updatedWeek": updatedWeek });

        } else {

            const retrieved_updatedSecs = snapshot.child("updatedSecs").val();
            const retrieved_updatedDay = snapshot.child("updatedDay").val();
            const retrieved_updatedWeek = snapshot.child("updatedWeek").val();

            const currentTime = Date.now();

            // do some calculations with the above values and currentTime.
        }
    });
}

score 1 · Accepted Answer · answered Nov 10 '20 at 03:57

ServerValue.TIMESTAMP is not a standard integer timstamp value that you can do math on. It's a token, or sentinel value, that gets interpreted on the server when it receives the write. That's how it's able to take the actual server's timestamp value. The only way it makes sense to use is as a child's value at the time of a write.

Since you are running in Cloud Functions, you actually have a Google server timestamp value right there in memory - in the actual clock. All of Googles backends have synchronized clocks, so they are all accurate. You typically only use ServerValue.TIMESTAMP in a client app when you can't be certain that the user's device has an accurate clock.

In your case, instead of using ServerValue.TIMESTAMP, you should simply take Date.now() as the current time.

score 0 · Answer 2 · answered Nov 10 '20 at 03:42

0

You need a closing parentheses after currentTimeStamp.

const updatedSecs = new Date(currentTimeStamp).getTime() + ten_secs;

answered Nov 10 '20 at 03:42

tbone849

925
8
18

If that works, you did the same thing each time you added time. I also removed the closing parentheses after ten_secs – tbone849 Nov 10 '20 at 03:47
I added the same exact code that you did, I get the same error: `getTime is not a function` – Lance Samaria Nov 10 '20 at 03:49
You did same thing on the other lines you used getTime(). Fix each instance – tbone849 Nov 10 '20 at 03:51
that code results in a `NaN` value: `@firebase/database: FIREBASE WARNING: Exception was thrown by user callback. Error: Reference.set failed: First argument contains NaN in property` – Lance Samaria Nov 10 '20 at 03:57
read @DougStevenson answer. thanks for trying to help me! – Lance Samaria Nov 10 '20 at 04:03

Lance Samaria · Answer 3 · 2020-11-10T05:08:41.547

@DougStevenson's answer worked but I ran into another problem where getTime is not a function still kept appearing. I had to use .valueOf() instead.

Here is the updated code:

const currentTimeStamp = Date.now(); // DougStevenson answer

const updatedSecs = currentTimeStamp.valueOf() + ten_secs;

const updatedDay = currentTimeStamp.valueOf() + daily_secs;

const updatedWeek = currentTimeStamp.valueOf() + weekly_secs;

How to add time to a firebase.database.ServerValue.TIMESTAMP

3 Answers3