Firebase Realtime Database Cheatsheet

Firebase Realtime Database is a powerful cloud-hosted NoSQL database provided by Google as a part of the Firebase platform. It enables developers to build real-time applications by storing and synchronizing data in JSON format. This cheatsheet serves as a quick reference guide for common Firebase Realtime Database operations.

Setting up Firebase

To get started, you need to set up Firebase in your project. If you haven’t done this yet, follow these steps:

1. Create a Firebase Project:

• Go to the Firebase Console.
• Click on “Add Project” and follow the setup instructions.

1. Add Your App:

• Once your project is created, click on “Add App” and choose your platform (iOS, Android, or Web).

1. Get Configuration:

• After adding your app, Firebase will provide you with configuration details. For a web app, this includes a config object with API keys and other settings.

1. Initialize Firebase:

• In your code, initialize Firebase with the provided configuration.

import firebase from 'firebase/app'; 
import 'firebase/database'; 
const config = { 
    apiKey: "YOUR_API_KEY", 
    authDomain: "YOUR_AUTH_DOMAIN", 
    databaseURL: "YOUR_DATABASE_URL", 
    projectId: "YOUR_PROJECT_ID", 
    storageBucket: "YOUR_STORAGE_BUCKET", 
    messagingSenderId: "YOUR_MESSAGING_SENDER_ID", 
    appId: "YOUR_APP_ID" 
}; 
firebase.initializeApp(config);

CRUD Operations

1. Read Data

Get a Snapshot of Data

const dbRef = firebase.database().ref('path/to/data');
dbRef.once('value')
  .then(snapshot => {
    const data = snapshot.val();
    console.log(data);
  })
  .catch(error => {
    console.error(error);
  });

2. Write Data

Set Data

const newData = { key1: 'value1', key2: 'value2' };
firebase.database().ref('path/to/data').set(newData);

Update Data

const updateData = { key2: 'new value' };
firebase.database().ref('path/to/data').update(updateData);

Push Data (Automatically Generates Unique Key)

const newData = { key1: 'value1', key2: 'value2' };
firebase.database().ref('path/to/data').push(newData);

3. Delete Data

Remove Data

firebase.database().ref('path/to/data').remove();

Real-time Updates

4. Listening for Changes

On Value Changes

const dbRef = firebase.database().ref('path/to/data');
dbRef.on('value', snapshot => {
  const data = snapshot.val();
  console.log(data);
});

On Child Added

const dbRef = firebase.database().ref('path/to/data');
dbRef.on('child_added', snapshot => {
  const newChildData = snapshot.val();
  console.log(newChildData);
});

On Child Changed

const dbRef = firebase.database().ref('path/to/data');
dbRef.on('child_changed', snapshot => {
  const updatedChildData = snapshot.val();
  console.log(updatedChildData);
});

On Child Removed

const dbRef = firebase.database().ref('path/to/data');
dbRef.on('child_removed', snapshot => {
  const removedChildData = snapshot.val();
  console.log(removedChildData);
});

Security Rules

Firebase Realtime Database security rules are crucial to protect your data. Ensure you configure them appropriately in the Firebase Console.

For more detailed information, refer to the official Firebase Realtime Database Documentation.

FAQ