User profile data in Firebase - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ service_behavior

intermediate

How does Firebase Authentication handle user profile updates?

When a user updates their profile information using Firebase Authentication's updateProfile method, what happens to the stored user data?

A The profile data update triggers a full user account deletion and recreation.

B The profile data is updated on Firebase servers and immediately reflected in the user's authentication token.

C The profile data is updated on Firebase servers but requires the user to sign out and sign in again to see changes.

D The profile data is updated only locally on the client and not saved to Firebase servers.

💡 Hint

Think about how Firebase keeps user data consistent across sessions.

Firebase Authentication updates the user profile data on its servers and refreshes the user's token so changes are immediately available.

❓ Architecture

intermediate

Best practice for storing user profile data in Firebase

Which Firebase service is best suited for storing detailed user profile data that can be queried and updated frequently?

A Firebase Cloud Firestore

B Firebase Realtime Database

C Firebase Authentication user profile fields only

D Firebase Cloud Storage

💡 Hint

Consider which service supports flexible queries and structured data.

Cloud Firestore is designed for structured, queryable, and frequently updated data like user profiles.

❓ security

advanced

Securing user profile data in Firebase Firestore

Given a Firestore collection 'users' where each document ID matches the user's UID, which security rule correctly restricts read and write access so users can only access their own profile data?

Firebase

rules_version = '2';
service cloud.firestore {
  match /databases/{database}/documents {
    match /users/{userId} {
      allow read, write: if request.auth.uid == userId;
    }
  }
}

A request.auth.token.email_verified == true

B request.time < timestamp.date(2025, 1, 1)

C request.auth.uid != userId

D request.auth.uid == userId

💡 Hint

Think about how to match the authenticated user with the document ID.

The rule allows access only if the authenticated user's UID matches the document ID, ensuring users access only their own data.

❓ Configuration

advanced

Firebase Cloud Functions to update user profile data

You want to automatically update a user's profile document in Firestore whenever their Firebase Authentication profile changes. Which Cloud Function trigger should you use?

A functions.auth.user().onUpdate()

B functions.firestore.document('users/{userId}').onUpdate()

C functions.auth.user().onCreate()

D functions.database.ref('/users/{userId}').onWrite()

💡 Hint

Consider which event fires when a Firebase Authentication user profile changes.

The onUpdate trigger on functions.auth.user() fires when a user's authentication profile is updated.

✅ Best Practice

expert

Handling user profile data consistency across Firebase Authentication and Firestore

What is the best approach to keep user profile data consistent between Firebase Authentication and Firestore when users update their profile?

A Update Firebase Authentication profile only and ignore Firestore data.

B Manually update both Firebase Authentication and Firestore profiles on the client side without synchronization.

C Use a Cloud Function triggered on Firebase Authentication user update to sync changes to Firestore.

D Update Firestore profile only and do not update Firebase Authentication profile.

💡 Hint

Think about automating synchronization to avoid data mismatch.

Using a Cloud Function triggered by Firebase Authentication updates ensures Firestore data stays consistent automatically.