How do I use Firebase Admin SDK to change data in Firebase Realtime Database while using Cloud Functions?

Question

I want to reset a specific value in my Firebase Realtime Database every day at 12:00 AM. To do this, I'm using the Firebase Admin SDK to change the data in Firebase Realtime Database and Cloud Functions to trigger the change at 12:00 AM every day.

This is an example structure of my Firebase Realtime Database:

{
  "users": {
    "fa54487d9cbb4214b00db80e2118e4e6": {
      "daily": 10
    }
  }
}

This is the code in my index.js :

// The Cloud Functions for Firebase SDK to create Cloud Functions and setup triggers.
var functions = require('firebase-functions');

// The Firebase Admin SDK to access Cloud Firestore.
var admin = require('firebase-admin');

// Fetch the service account key JSON file contents
var serviceAccount = require("serviceAccountKey.json");

// Initialize the app with a service account, granting admin privileges
admin.initializeApp({
  credential: admin.credential.cert(serviceAccount),
  databaseURL: "https://databaseName.firebaseio.com"
});

// As an admin, the app has access to read and write all data, regardless of Security Rules
var db = admin.database();
var ref = db.ref("users");

// Reset today GHG emissions at 12:00 AM everyday
exports.dailyReset = functions.pubsub.schedule('0 0 * * *').onRun((context) => {
    usersRef.child("{userId}").set({
      daily: 0
    });
});

Deploy Error:

: functions[dailyReset(us-central1)]. Deployment error.

Function failed on loading user code. This is likely due to a bug in the user code. Error message: Error: please examine your function logs to see the error cause: https://cloud.google.com/functions/docs/monitoring/logging#viewing_logs . Additional troubleshooting documentation can be found athttps://cloud.google.com/functions/docs/troubleshooting#logging . Please visit https://cloud.google.com/functions/docs/troubleshooting for in-depth troubleshooting documentation.

Firebase Console Functions Logs:

Error: function terminated. Recommended action: inspect logs for termination reason.

Additional troubleshooting documentation can be found athttps://cloud.google.com/functions/docs/troubleshooting#logging Function cannot be initialized.

{"@type":"type.googleapis.com/google.cloud.audit.AuditLog","status":{"code":3,"message":"Function failed on loading user code. This is likely due to a bug in the user code.

Error message: Error: please examine your function logs to see the error cause: https://cloud.google.com/functions/docs/monitoring/logging#viewing_logs .

Additional troubleshooting documentation can be found athttps://cloud.google.com/functions/docs/troubleshooting#logging .

The script won't deploy when I use firebase deploy as my function is giving me an error. Can someone tell me how to fix my code?

Answer 1

This won't work:

exports.dailyReset = functions.pubsub.schedule('0 0 * * *').onRun((context) => {
    usersRef.child("{userId}").set({
      daily: 0
    });
});

There is nothing here that interprets the {userId} in that path, so the database updates the literal path "/users/{userId}" , which is not what you want.

If you know what user ID you want to update, you should use that value in the path:

exports.dailyReset = functions.pubsub.schedule('0 0 * * *').onRun((context) => {
    let usersRef = admin.database().ref("users");
    usersRef.child("theActualUserIdYouWantToUpdate").set({
      daily: 0
    });
});

If you don't know what user ID to update, you'll need to query the database to determine that.

---

If you want to loop over all users, you can do:

exports.dailyReset = functions.pubsub.schedule('0 0 * * *').onRun((context) => {
    return usersRef.once("value").then((snapshot) => {
        let updates = {};
        snapshot.forEach((userSnapshot) => {
            updates[userSnapshot.key+"/daily"] = 0
        });
        return usersRef.update(updates);
    });
});

If you are new to JavaScript or interacting with the Realtime Database in it, Cloud Functions for Firebase is not the best way to learn it. I recommend first reading the Firebase documentation for Web developers and/or taking the Firebase codelab for Web developer . They cover many basic JavaScript, Web and Firebase interactions. You could also use the Admin SDK in a local Node.js process, which can be debugged with a local debugger. After those you'll be much better equipped to write code for Cloud Functions too.