Updating specific fields in Firebase - Mini Project: Build & Apply

Updating Specific Fields in Firebase Firestore

📖 Scenario: You are managing a small app's user data stored in Firebase Firestore. You want to update only certain fields of a user's document without changing the entire document.

🎯 Goal: Learn how to update specific fields in a Firestore document using Firebase SDK.

📋 What You'll Learn

Create a Firestore document with initial user data

Add a configuration variable for the user ID

Write code to update specific fields in the Firestore document

Complete the update operation with proper Firestore method

💡 Why This Matters

🌍 Real World

Updating specific fields in Firestore is common when you want to change user profile details without affecting other data.

💼 Career

Knowing how to update fields in Firestore is essential for frontend and backend developers working with Firebase apps.

1

Create initial user data document

Create a Firestore document reference called userDoc pointing to the collection users and document ID user123. Then create an object called initialData with these exact fields: name set to "Alice", age set to 30, and city set to "New York".

Firebase

// Your code here to create userDoc and initialData

Need a hint?

Use firestore.collection('users').doc('user123') to get the document reference.

2

Add user ID configuration variable

Create a constant variable called userId and set it to the string "user123".

Firebase

const userDoc = firestore.collection('users').doc('user123');
const initialData = { name: "Alice", age: 30, city: "New York" };
// Your code here to create userId

Need a hint?

Define userId before using it in userDoc.

3

Write update data object

Create an object called updateData with these exact fields: age set to 31 and city set to "Boston". This object will hold the fields to update.

Firebase

const userId = "user123";
const userDoc = firestore.collection('users').doc(userId);
const initialData = { name: "Alice", age: 30, city: "New York" };
// Your code here to create updateData

Need a hint?

Only include the fields you want to change in updateData.

4

Update specific fields in Firestore document

Use the update method on userDoc to update the document with the fields in updateData.

Firebase

const userId = "user123";
const userDoc = firestore.collection('users').doc(userId);
const initialData = { name: "Alice", age: 30, city: "New York" };
const updateData = { age: 31, city: "Boston" };
// Your code here to update userDoc

Need a hint?

Use userDoc.update(updateData) to change only the specified fields.