How to Use Firestore with Node.js: Simple Guide

To use Firestore with Node.js, install the @google-cloud/firestore package, initialize a Firestore client with your project ID, and then use the client to read or write data. This setup lets your Node.js app interact with Firestore's NoSQL database easily.

Syntax

First, install the Firestore library. Then, import and create a Firestore client by specifying your Google Cloud project ID. Use this client to access collections and documents.

• Import Firestore: Load the Firestore library.
• Initialize client: Connect to your Firestore database.
• Access data: Use methods like collection(), doc(), get(), and set() to read and write.

javascript

const { Firestore } = require('@google-cloud/firestore');

async function main() {
  const firestore = new Firestore({
    projectId: 'your-project-id',
  });

  // Access a collection
  const usersCollection = firestore.collection('users');

  // Access a document
  const userDoc = usersCollection.doc('user-id');

  // Read document data
  const snapshot = await userDoc.get();
  if (snapshot.exists) {
    console.log(snapshot.data());
  }

  // Write document data
  await userDoc.set({ name: 'Alice', age: 30 });
}

main().catch(console.error);

Example

This example shows how to connect to Firestore, add a new user document, and then read it back to print the data.

javascript

const { Firestore } = require('@google-cloud/firestore');

async function runExample() {
  const firestore = new Firestore({
    projectId: 'your-project-id',
  });

  const userRef = firestore.collection('users').doc('user1');

  // Write data
  await userRef.set({ name: 'Alice', age: 30 });

  // Read data
  const doc = await userRef.get();
  if (doc.exists) {
    console.log('User data:', doc.data());
  } else {
    console.log('No such document!');
  }
}

runExample().catch(console.error);

Output

User data: { name: 'Alice', age: 30 }

Common Pitfalls

Common mistakes include:

• Not installing @google-cloud/firestore before use.
• Forgetting to set the correct projectId or authentication credentials.
• Using await without async functions causing errors.
• Trying to read a document that does not exist without checking exists.

Always handle promises properly and check if documents exist before accessing data.

javascript

/* Wrong: Missing async and await */
async function wrongExample() {
  const doc = firestore.collection('users').doc('user1').get();
  console.log((await doc).data()); // Error: doc is a Promise if not awaited
}

/* Right: Use async/await */
async function readDoc() {
  const doc = await firestore.collection('users').doc('user1').get();
  if (doc.exists) {
    console.log(doc.data());
  } else {
    console.log('No document found');
  }
}

Quick Reference

Key Firestore methods for Node.js:

Method	Description
Firestore()	Create a Firestore client instance
collection(name)	Access a collection by name
doc(id)	Access a document by ID
get()	Read data from a document or collection
set(data)	Write data to a document
update(data)	Update fields in a document
delete()	Delete a document

Key Takeaways

Install and import @google-cloud/firestore to use Firestore in Node.js.

Initialize Firestore with your Google Cloud project ID before accessing data.

Use async/await to handle Firestore operations and check if documents exist.

Common errors come from missing async or incorrect project setup.

Use Firestore methods like collection(), doc(), get(), and set() to manage data.