Getting a single document in Firebase - Mini Project: Build & Apply

Getting a Single Document from Firebase Firestore

📖 Scenario: You are building a simple app that needs to fetch user profile information stored in Firebase Firestore. You want to get the data of a single user by their unique ID.

🎯 Goal: Learn how to write code that retrieves a single document from a Firestore collection using the document ID.

📋 What You'll Learn

Create a Firestore collection reference

Set a variable with the document ID to fetch

Write the code to get the document snapshot

Access the document data safely

💡 Why This Matters

🌍 Real World

Fetching a single user profile or settings document from Firestore is common in apps that personalize content or manage user data.

💼 Career

Understanding how to retrieve single documents from Firestore is essential for frontend and backend developers working with Firebase to build real-time, scalable applications.

1

Create a Firestore collection reference

Write a line of code to create a Firestore collection reference called usersRef that points to the collection named users using firebase.firestore().collection('users').

Firebase

// Create a Firestore collection reference called usersRef
// Your code here

Need a hint?

Use firebase.firestore().collection('users') to get the collection reference.

2

Set the document ID to fetch

Create a constant variable called userId and set it to the string 'user123', which is the ID of the user document you want to get.

Firebase

const usersRef = firebase.firestore().collection('users');
// Create a constant userId with value 'user123'
// Your code here

Need a hint?

Use const userId = 'user123'; to store the document ID.

3

Write the code to get the document snapshot

Write an asynchronous function called getUserData that uses usersRef.doc(userId).get() to get the document snapshot and stores it in a variable called doc.

Firebase

const usersRef = firebase.firestore().collection('users');
const userId = 'user123';

// Write async function getUserData to get document snapshot
// Your code here

Need a hint?

Use await usersRef.doc(userId).get() inside an async function to get the document.

4

Access the document data safely

Inside the getUserData function, add code to check if doc.exists is true. If yes, create a variable called userData and set it to doc.data(). This will hold the user's data.

Firebase

const usersRef = firebase.firestore().collection('users');
const userId = 'user123';

async function getUserData() {
    const doc = await usersRef.doc(userId).get();
    // Check if document exists and get data
    // Your code here
}

Need a hint?

Use if (doc.exists) to check if the document was found, then use doc.data() to get its contents.