The Project | About Us | Contribute | Donations | License
HOME My courses Completed
◄ Previous
◄

Triggering Functions

Next ►
►

In this section, we will explore how to trigger Firebase Functions. Firebase Functions can be triggered by various events, such as changes in the Firebase Realtime Database, Firestore, Authentication events, HTTP requests, and more. Understanding how to set up these triggers is crucial for building responsive and dynamic applications.

Types of Triggers

Firebase Functions can be triggered by the following types of events:

  1. HTTP Triggers: Functions that are triggered by HTTP requests.
  2. Database Triggers: Functions that respond to changes in the Firebase Realtime Database.
  3. Firestore Triggers: Functions that respond to changes in Firestore documents.
  4. Authentication Triggers: Functions that respond to user creation and deletion events.
  5. Storage Triggers: Functions that respond to changes in Firebase Storage.
  6. Analytics Triggers: Functions that respond to Firebase Analytics events.
  7. Pub/Sub Triggers: Functions that respond to messages published to Google Cloud Pub/Sub topics.

HTTP Triggers

HTTP triggers are the simplest type of trigger. They allow you to create functions that can be invoked via HTTP requests.

Example

const functions = require('firebase-functions');

exports.helloWorld = functions.https.onRequest((request, response) => {
  response.send("Hello from Firebase!");
});

Explanation

  • functions.https.onRequest: This method sets up an HTTP trigger.
  • request: The HTTP request object.
  • response: The HTTP response object.

Exercise

Create an HTTP-triggered function that returns the current server time.

const functions = require('firebase-functions');

exports.getTime = functions.https.onRequest((request, response) => {
  const currentTime = new Date().toISOString();
  response.send(`Current server time is: ${currentTime}`);
});

Database Triggers

Database triggers respond to changes in the Firebase Realtime Database.

Example

const functions = require('firebase-functions');

exports.onUserCreate = functions.database.ref('/users/{userId}')
  .onCreate((snapshot, context) => {
    const newUser = snapshot.val();
    console.log('New user created:', newUser);
    return null;
  });

Explanation

  • functions.database.ref('/users/{userId}'): This method sets up a trigger for changes at the specified database path.
  • onCreate: This event is triggered when a new child is added to the specified path.
  • snapshot: Contains the data of the newly created child.
  • context: Contains metadata about the event.

Exercise

Create a database-triggered function that logs a message whenever a user is deleted.

const functions = require('firebase-functions');

exports.onUserDelete = functions.database.ref('/users/{userId}')
  .onDelete((snapshot, context) => {
    const deletedUser = snapshot.val();
    console.log('User deleted:', deletedUser);
    return null;
  });

Firestore Triggers

Firestore triggers respond to changes in Firestore documents.

Example

const functions = require('firebase-functions');

exports.onDocumentCreate = functions.firestore.document('/users/{userId}')
  .onCreate((snap, context) => {
    const newValue = snap.data();
    console.log('New document created:', newValue);
    return null;
  });

Explanation

  • functions.firestore.document('/users/{userId}'): This method sets up a trigger for changes to the specified Firestore document.
  • onCreate: This event is triggered when a new document is created.
  • snap: Contains the data of the newly created document.
  • context: Contains metadata about the event.

Exercise

Create a Firestore-triggered function that logs a message whenever a document is updated.

const functions = require('firebase-functions');

exports.onDocumentUpdate = functions.firestore.document('/users/{userId}')
  .onUpdate((change, context) => {
    const newValue = change.after.data();
    const previousValue = change.before.data();
    console.log('Document updated from', previousValue, 'to', newValue);
    return null;
  });

Authentication Triggers

Authentication triggers respond to user creation and deletion events.

Example

const functions = require('firebase-functions');

exports.onUserCreate = functions.auth.user().onCreate((user) => {
  console.log('New user created:', user.email);
  return null;
});

Explanation

  • functions.auth.user().onCreate: This method sets up a trigger for user creation events.
  • user: Contains the data of the newly created user.

Exercise

Create an authentication-triggered function that logs a message whenever a user is deleted.

const functions = require('firebase-functions');

exports.onUserDelete = functions.auth.user().onDelete((user) => {
  console.log('User deleted:', user.email);
  return null;
});

Conclusion

In this section, we covered the various types of triggers available in Firebase Functions, including HTTP, Database, Firestore, and Authentication triggers. We provided examples and exercises to help you understand how to set up and use these triggers effectively. Understanding how to trigger functions is essential for building dynamic and responsive applications with Firebase. In the next section, we will delve into deploying these functions to Firebase.

◄ Previous
◄
Next ►
►
The Project | About Us | Contribute | Donations | License
© Copyright 2024. All rights reserved