Batch writes in Firebase - Mini Project: Build & Apply

Batch writes

📖 Scenario: You are building a simple app that needs to add multiple user profiles to a Firestore database at once. To keep the data consistent and save time, you will use batch writes.

🎯 Goal: Create a Firestore batch write that adds three user documents with exact data in a single commit.

📋 What You'll Learn

Create a Firestore batch instance

Add three user documents with specified IDs and fields to the batch

Commit the batch to write all documents at once

💡 Why This Matters

🌍 Real World

Batch writes are used to perform multiple database changes at once, ensuring all succeed or fail together. This is useful for syncing related data or improving performance.

💼 Career

Understanding batch writes is important for backend and full-stack developers working with Firestore to maintain data consistency and optimize database operations.

1

Initialize Firestore and batch

Create a variable called db that initializes Firestore using getFirestore(). Then create a variable called batch that initializes a batch write using writeBatch(db).

Firebase

# Your code here

Need a hint?

Use getFirestore() to get the Firestore instance and writeBatch(db) to start a batch.

2

Prepare user document references

Create three variables called userRef1, userRef2, and userRef3. Each should use doc(db, 'users', 'user1'), doc(db, 'users', 'user2'), and doc(db, 'users', 'user3') respectively to reference documents in the 'users' collection.

Firebase

import { getFirestore, writeBatch, doc } from 'firebase/firestore';

const db = getFirestore();
const batch = writeBatch(db);

# Your code here

Need a hint?

Use doc(db, 'users', 'userX') to get document references for each user.

3

Add user data to batch

Use batch.set() to add three user documents to the batch. For userRef1, set {name: 'Alice', age: 30}. For userRef2, set {name: 'Bob', age: 25}. For userRef3, set {name: 'Charlie', age: 35}.

Firebase

import { getFirestore, writeBatch, doc } from 'firebase/firestore';

const db = getFirestore();
const batch = writeBatch(db);

const userRef1 = doc(db, 'users', 'user1');
const userRef2 = doc(db, 'users', 'user2');
const userRef3 = doc(db, 'users', 'user3');

# Your code here

Need a hint?

Use batch.set(documentRef, data) to add each user document to the batch.

4

Commit the batch write

Add a line to commit the batch write using await batch.commit(). Make sure the function is async or use a top-level await if supported.

Firebase

import { getFirestore, writeBatch, doc } from 'firebase/firestore';

const db = getFirestore();
const batch = writeBatch(db);

const userRef1 = doc(db, 'users', 'user1');
const userRef2 = doc(db, 'users', 'user2');
const userRef3 = doc(db, 'users', 'user3');

batch.set(userRef1, { name: 'Alice', age: 30 });
batch.set(userRef2, { name: 'Bob', age: 25 });
batch.set(userRef3, { name: 'Charlie', age: 35 });

# Your code here

Need a hint?

Use await batch.commit() to send all writes to Firestore at once.