In this codelab, you'll learn how to use Firebase to easily create web applications by implementing and deploying a chat client using Firebase products and services.

What you'll learn

What you'll need

Clone the codelab's GitHub repository from the command line: 

git clone https://github.com/Zenika/firebase-web-101

Alternatively, if you do not have git installed, you can download the repository as a ZIP file.

Import the starter app

Using your IDE, open or import the 📁 web-start directory from the cloned repository. This 📁 web-start directory contains the starting code for the codelab, which will be a fully functional chat web app.

Create a Firebase project

  1. Sign in to Firebase.
  2. In the Firebase console, click Add Project, and then name your Firebase project FriendlyChat. Remember the project ID for your Firebase project.
  3. Click Create Project.

The application that we're going to build uses Firebase products that are available for web apps:

Some of these products need special configuration or need to be enabled using the Firebase console.

Add a Firebase web app to the project

  1. Click the web icon to create a new Firebase web app.
  2. Register the app with the nickname Friendly Chat, then check the box next to Also set up Firebase Hosting for this app. Click Register app.
  3. Click through the remaining steps. You don't need to follow the instructions now; these will be covered in later steps of this codelab.

Enable Google sign-in for Firebase Authentication

To allow users to sign in to the web app with their Google accounts, we'll use the Google sign-in method.

You'll need to enable Google sign-in:

  1. In the Firebase console, locate the Develop section in the left panel.
  2. Click Authentication, then click the Sign-in method tab (or click here to go directly there).
  3. Enable the Google Sign-in Provider, then click Save.
  4. Set the public-facing name of your app to Friendly Chat and choose a Project support email from the dropdown menu.
  5. Configure your OAuth consent screen in the Google Cloud Console. Add a logo,

Enable Cloud Firestore

The web app uses Cloud Firestore to save chat messages and receive new chat messages.

You'll need to enable Cloud Firestore:

  1. In the Firebase console's Develop section, click Database.
  2. Click Create database in the Cloud Firestore pane.

  1. Select the Start in test mode option, then click Next after reading the disclaimer about the security rules.

Test mode ensures that we can freely write to the database during development. We'll make our database more secure later on in this codelab.

  1. Set the location where your Cloud Firestore data is stored. You can leave this as the default or choose a region close to you. Click Done to provision Firestore.

Enable Cloud Storage

The web app uses Cloud Storage for Firebase to store, upload, and share pictures.

You'll need to enable Cloud Storage:

  1. In the Firebase console's Develop section, click Storage.
  2. Click Get Started.
  3. Read the disclaimer about security rules for your Firebase project, then click Next.

With the default security rules, any authenticated user can write anything to Cloud Storage. We'll make our storage more secure later in this codelab.

  1. The Cloud Storage location is preselected with the same region you chose for your Cloud Firestore database. Click Done to complete the setup.

The Firebase command-line interface (CLI) allows you to use Firebase Hosting to serve your web app locally, as well as to deploy your web app to your Firebase project.

  1. Install the CLI by running the following npm command:
npm -g install firebase-tools
  1. Verify that the CLI has been installed correctly by running the following command: 
firebase --version

Make sure that the version of the Firebase CLI is v4.1.0 or later.

  1. Authorize the Firebase CLI by running the following command:
firebase login

We've set up the web app template to pull your app's configuration for Firebase Hosting from your app's local directory (the repository that you cloned earlier in the codelab). But to pull the configuration, we need to associate your app with your Firebase project.

  1. Make sure that your command line is accessing your app's local web-start directory.
  1. Associate your app with your Firebase project by running the following command: 
firebase use --add
  1. When prompted, select your Project ID, then give your Firebase project an alias.

An alias is useful if you have multiple environments (production, staging, etc). However, for this codelab, let's just use the alias of default.

  1. Follow the remaining instructions on your command line.

Now that you have imported and configured your project, you are ready to run the web app for the first time.

  1. In a console from the web-start directory, run the following Firebase CLI command: 
firebase serve --only hosting
  1. Your command line should display the following response:
✔  hosting: Local server: http://localhost:5000

We're using the Firebase Hosting emulator to serve our app locally. The web app should now be available from http://localhost:5000. All the files that are located under the public subdirectory are served.

  1. Using your browser, open your app at http://localhost:5000.

You should see your FriendlyChat app's UI, which is not (yet!) functioning:

The app cannot do anything right now, but with your help it will soon! We've only laid out the UI for you so far.

Let's now build a realtime chat!

Import the Firebase SDK

We need to import the Firebase SDK into the app. There are multiple ways to do this as described in our documentation. For instance, you can import the library from our CDN. Or you can install it locally using npm, then package it in your app if you're using Browserify.

Since we're using Firebase Hosting to serve our app, we're going to import the local URLs that are in the file index.html (located in your web-start/public/ directory). For this codelab, we've already added the following lines for you at the bottom of the index.html file, but you can double check that they are there.

index.html 

<script src="/__/firebase/6.4.0/firebase-app.js"></script>
<script src="/__/firebase/6.4.0/firebase-auth.js"></script>
<script src="/__/firebase/6.4.0/firebase-storage.js"></script>
<script src="/__/firebase/6.4.0/firebase-messaging.js"></script>
<script src="/__/firebase/6.4.0/firebase-firestore.js"></script>
<script src="/__/firebase/6.4.0/firebase-performance.js"></script>

During this codelab, we're going to use Firebase Authentication, Cloud Firestore, Cloud Storage, Cloud Messaging, and Performance Monitoring, so we're importing all of their libraries. In your future apps, make sure that you're only importing the parts of Firebase that you need, to shorten the load time of your app.

Configure Firebase

We also need to configure the Firebase SDK to tell it which Firebase project that we're using. Since we're using Firebase Hosting, you can import a special script that will do this configuration for you. Again, for this codelab, we've already added the following line for you at the bottom of the public/index.html file, but double-check that it is there.

index.html 

<script src="/__/firebase/init.js"></script>

This script contains your Firebase project configuration based upon the Firebase project that you specified earlier when you ran firebase use --add.

Feel free to inspect the file init.js to see what your project configuration looks like. To do this, open http://localhost:5000/__/firebase/init.js in your browser. You should see something that looks like the following:

/__/firebase/init.js 

if (typeof firebase === 'undefined') throw new Error('hosting/init-error: Firebase SDK not detected. You must include it before /__/firebase/init.js');
firebase.initializeApp({
  "apiKey": "qwertyuiop_asdfghjklzxcvbnm1234568_90",
  "databaseURL": "https://friendlychat-1234.firebaseio.com",
  "storageBucket": "friendlychat-1234.appspot.com",
  "authDomain": "friendlychat-1234.firebaseapp.com",
  "messagingSenderId": "1234567890",
  "projectId": "friendlychat-1234",
  "appId": "1:1234567890:web:123456abcdef"
});

The Firebase SDK should now be ready to use since it's imported and initialized in index.html. We're now going to implement user sign-in using Firebase Authentication.

Authenticate your users with Google Sign-In

In the app, when a user clicks the Sign in with Google button, the signIn function is triggered. (We already set that up for you!) For this codelab, we want to authorize Firebase to use Google as the identity provider. We'll use a popup, but several other methods are available from Firebase.

  1. In the web-start directory, in the subdirectory public/scripts/, open main.js.
  2. Find the function signIn.
  3. Replace the entire function with the following code.

main.js 

// Signs-in Friendly Chat.
function signIn() {
  // Sign into Firebase using popup auth & Google as the identity provider.
  var provider = new firebase.auth.GoogleAuthProvider();
  firebase.auth().signInWithPopup(provider);
}

The signOut function is triggered when the user clicks the Sign out button.

  1. Go back to the file public/scripts/main.js.
  2. Find the function signOut.
  3. Replace the entire function with the following code.

main.js 

// Signs-out of Friendly Chat.
function signOut() {
  // Sign out of Firebase.
  firebase.auth().signOut();
}

Track the authentication state

To update our UI accordingly, we need a way to check if the user is signed in or signed out. With Firebase Authentication, you can register an observer on the authentication state that will be triggered each time the authentication state changes.

  1. Go back to the file public/scripts/main.js.
  2. Find the function initFirebaseAuth.
  3. Replace the entire function with the following code.

main.js 

// Initiate Firebase Auth.
function initFirebaseAuth() {
  // Listen to auth state changes.
  firebase.auth().onAuthStateChanged(authStateObserver);
}

The code above registers the function authStateObserver as the authentication state observer. It will trigger each time the authentication state changes (when the user signs in or signs out). It's at this point that we'll update the UI to display or hide the sign-in button, the sign-out button, the signed-in user's profile picture, and so on. All of these UI parts have already been implemented.

Display the information of the signed-in user

We want to display the signed-in user's profile picture and user name in the top bar of our app. In Firebase, the signed-in user's data is always available in the firebase.auth().currentUser object. Earlier, we set up the authStateObserver function to trigger when the user signs in so that our UI updates accordingly. It will call getProfilePicUrl and getUserName when triggered.

  1. Go back to the file public/scripts/main.js.
  2. Find the functions getProfilePicUrl and getUserName.
  3. Replace both functions with the following code.

main.js 

// Returns the signed-in user's profile pic URL.
function getProfilePicUrl() {
  return firebase.auth().currentUser.photoURL || '/images/profile_placeholder.png';
}

// Returns the signed-in user's display name.
function getUserName() {
  return firebase.auth().currentUser.displayName;
}

We display an error message if the user tries to send messages when the user isn't signed in. (You can try it, though!) So, we need to detect if the user is actually signed in.

  1. Go back to the file public/scripts/main.js.
  2. Find the function isUserSignedIn.
  3. Replace the entire function with the following code.

main.js 

// Returns true if a user is signed-in.
function isUserSignedIn() {
  return !!firebase.auth().currentUser;
}

Test signing in to the app

  1. If your app is still being served, refresh your app in the browser. Otherwise, run firebase serve on the command line to start serving the app from http://localhost:5000, and then open it in your browser.
  2. Sign in to the app using the sign-in button and your Google account. If you see an error message stating auth/operation-not-allowed, check to make sure that you enabled Google Sign-in as an authentication provider in the Firebase console
  3. After signing in, your profile picture and user name should be displayed:

In this section, we'll write some data to Cloud Firestore so that we can populate the app's UI. This can be done manually with the Firebase console, but we'll do it in the app itself to demonstrate a basic Cloud Firestore write.

Data model

Cloud Firestore data is split into collections, documents, fields, and subcollections. We will store each message of the chat as a document in a top-level collection called messages.

Add messages to Cloud Firestore

To store the chat messages that are written by users, we'll use Cloud Firestore.

In this section, you'll add the functionality for users to write new messages to your database. A user clicking the SEND button will trigger the code snippet below. It adds a message object with the contents of the message fields to your Cloud Firestore instance in the messages collection. The add() method adds a new document with an automatically generated ID to the collection.

  1. Go back to the file public/scripts/main.js.
  2. Find the function saveMessage.
  3. Replace the entire function with the following code.

main.js 

// Saves a new message to your Cloud Firestore database.
function saveMessage(messageText) {
  // Add a new message entry to the database.
  return firebase.firestore().collection('messages').add({
    name: getUserName(),
    text: messageText,
    profilePicUrl: getProfilePicUrl(),
    timestamp: firebase.firestore.FieldValue.serverTimestamp()
  }).catch(function(error) {
    console.error('Error writing new message to database', error);
  });
}

Test sending messages

  1. If your app is still being served, refresh your app in the browser. Otherwise, run firebase serve on the command line to start serving the app from http://localhost:5000, and then open it in your browser.
  2. After signing in, enter a message such as "Hey there!", and then click SEND. This will write the message into Cloud Firestore. However, you won't yet see the data in your actual web app because we still need to implement retrieving the data (the next section of the codelab).
  3. You can see the newly added message in your Firebase Console. Open your Firebase Console. Under the Develop section click Database (or click here and select your project) and you should see the messages collection with your newly added message:

Synchronize messages

To read messages in the app, we'll need to add listeners that trigger when data changes and then create a UI element that shows new messages.

We'll add code that listens for newly added messages from the app. In this code, we'll register the listener that listens for changes made to the data. We'll only display the last 12 messages of the chat to avoid displaying a very long history upon loading.

  1. Go back to the file public/scripts/main.js.
  2. Find the function loadMessages.
  3. Replace the entire function with the following code.

main.js 

// Loads chat messages history and listens for upcoming ones.
function loadMessages() {
  // Create the query to load the last 12 messages and listen for new ones.
  var query = firebase.firestore()
                  .collection('messages')
                  .orderBy('timestamp', 'desc')
                  .limit(12);

  // Start listening to the query.
  query.onSnapshot(function(snapshot) {
    snapshot.docChanges().forEach(function(change) {
      if (change.type === 'removed') {
        deleteMessage(change.doc.id);
      } else {
        var message = change.doc.data();
        displayMessage(change.doc.id, message.timestamp, message.name,
                       message.text, message.profilePicUrl, message.imageUrl);
      }
    });
  });
}

To listen to messages in the database, we create a query on a collection by using the .collection function to specify which collection the data that we want to listen to is in. In the code above, we're listening to the changes within the messages collection, which is where the chat messages are stored. We're also applying a limit by only listening to the last 12 messages using .limit(12) and ordering the messages by date using .orderBy('timestamp', 'desc') to get the 12 newest messages.

The .onSnapshot function takes one parameter: a callback function. The callback function will be triggered when there are any changes to documents that match the query. This could be if a message gets deleted, modified, or added. You can read more about this in the Cloud Firestore documentation.

Test synchronizing messages

  1. If your app is still being served, refresh your app in the browser. Otherwise, run firebase serve on the command line to start serving the app from http://localhost:5000, and then open it in your browser.
  2. The messages that you created earlier into the database should be displayed in the FriendlyChat UI (see below). Feel free to write new messages; they should appear instantly.
  3. (Optional) You can try manually deleting, modifying, or adding new messages directly in the Database section of the Firebase console; any changes should be reflected in the UI.

Congratulations! You are reading Cloud Firestore documents in your app!

View database security rules

Cloud Firestore uses a specific rules language to define access rights, security, and data validations.

When setting up the Firebase project at the beginning of this codelab, we chose to use "Test mode" default security rules so that we didn't restrict access to the datastore. In the Firebase console, in the Database section's Rules tab, you can view and modify these rules.

Right now, you should see the default rules, which do not restrict access to the datastore. This means that any user can read and write to any collections in your datastore. 

service cloud.firestore {
  match /databases/{database}/documents {
    match /{document=**} {
      allow read, write;
    }
  }
}

We'll update the rules to restrict things by using the following rules:

firestore.rules 

service cloud.firestore {
  match /databases/{database}/documents {
    // Messages:
    //   - Anyone can read.
    //   - Authenticated users can add and edit messages.
    //   - Validation: Check name is same as auth token and text length below 300 char or that imageUrl is a URL.
    //   - Deletes are not allowed.
    match /messages/{messageId} {
      allow read;
      allow create, update: if request.auth != null
                    && request.resource.data.name == request.auth.token.name
                    && (request.resource.data.text is string
                      && request.resource.data.text.size() <= 300
                      || request.resource.data.imageUrl is string
                      && request.resource.data.imageUrl.matches('https?://.*'));
      allow delete: if false;
    }
    // FCM Tokens:
    //   - Anyone can write their token.
    //   - Reading list of tokens is not allowed.
    match /fcmTokens/{token} {
      allow read: if false;
      allow write;
    }
  }
}

Update database security rules

There are two ways to edit your database security rules, either in the Firebase console or from a local rules file deployed using the Firebase CLI.

To update security rules in the Firebase console:

  1. Go to the Database section from the left panel, and then click the Rules tab.
  2. Replace the default rules that are already in the console with the rules shown above.
  3. Click Publish.

To update security rules from a local file:

  1. From the web-start directory, open firestore.rules.
  2. Replace the default rules that are already in the file with the rules shown above.
  3. From the web-start directory, open firebase.json.
  4. Add the firestore.rules attribute pointing to firestore.rules, as shown below. (The hosting attribute should already be in the file.)

firebase.json 

{
  // Add this!
  "firestore": {
    "rules": "firestore.rules"
  },
  "hosting": {
    "public": "./public"
  }
}
  1. Deploy the security rules using the Firebase CLI by running the following command: 
firebase deploy --only firestore
  1. Your command line should display the following response:
=== Deploying to 'friendlychat-1234'...

i  deploying firestore
i  firestore: checking firestore.rules for compilation errors...
✔  firestore: rules file firestore.rules compiled successfully
i  firestore: uploading rules firestore.rules...
✔  firestore: released rules firestore.rules to cloud.firestore

✔  Deploy complete!

Project Console: https://console.firebase.google.com/project/friendlychat-1234/overview

View Cloud Storage security rules

Cloud Storage for Firebase uses a specific rules language to define access rights, security, and data validations.

When setting up the Firebase project at the beginning of this codelab, we chose to use the default Cloud Storage security rule that only allows authenticated users to use Cloud Storage. In the Firebase console, in the Storage section's Rules tab, you can view and modify rules. You should see the default rule which allows any signed-in user to read and write any files in your storage bucket. 

service firebase.storage {
  match /b/{bucket}/o {
    match /{allPaths=**} {
      allow read, write: if request.auth != null;
    }
  }
}

We'll update the rules to do the following:

This can be implemented using the following rules:

storage.rules 

// Returns true if the uploaded file is an image and its size is below the given number of MB.
function isImageBelowMaxSize(maxSizeMB) {
  return request.resource.size < maxSizeMB * 1024 * 1024
      && request.resource.contentType.matches('image/.*');
}

service firebase.storage {
  match /b/{bucket}/o {
    match /{userId}/{messageId}/{fileName} {
      allow write: if request.auth != null && request.auth.uid == userId && isImageBelowMaxSize(5);
      allow read;
    }
  }
}

Update Cloud Storage security rules

There are two ways to edit your storage security rules: either in the Firebase console or from a local rules file deployed using the Firebase CLI.

To update security rules in the Firebase console:

  1. Go to the Storage section from the left panel, and then click the Rules tab.
  2. Replace the default rule that is already in the console with the rules shown above.
  3. Click Publish.

To update security rules from a local file:

  1. From the web-start directory, open storage.rules.
  2. Replace the default rules that are already in the file with the rules shown above.
  3. From the web-start directory, open firebase.json.
  4. Add the storage.rules attribute pointing to the storage.rules file, as shown below. (The hosting and database attribute should already be in the file.)

firebase.json 

{
  // If you went through the "Cloud Firestore Security Rules" step.
  "firestore": {
    "rules": "firestore.rules"
  },
  // Add this!
  "storage": {
    "rules": "storage.rules"
  },
  "hosting": {
    "public": "./public"
  }
}
  1. Deploy the security rules using the Firebase CLI by running the following command: 
firebase deploy --only storage
  1. Your command line should display the following response:
=== Deploying to 'friendlychat-1234'...

i  deploying storage
i  storage: checking storage.rules for compilation errors...
✔  storage: rules file storage.rules compiled successfully
i  storage: uploading rules storage.rules...
✔  storage: released rules storage.rules to firebase.storage/friendlychat-1234.appspot.com

✔  Deploy complete!

Project Console: https://console.firebase.google.com/project/friendlychat-1234/overview

Firebase offers a hosting service to serve your assets and web apps. You can deploy your files to Firebase Hosting using the Firebase CLI. Before deploying, you need to specify in your firebase.json file which local files should be deployed. For this codelab, we've already done this for you because this step was required to serve our files during this codelab. The hosting settings are specified under the hosting attribute:

firebase.json 

{
  // If you went through the "Cloud Firestore Security Rules" step.
  "firestore": {
    "rules": "firestore.rules"
  },
  // If you went through the "Storage Security Rules" step.
  "storage": {
    "rules": "storage.rules"
  },
  "hosting": {
    "public": "./public"
  }
}

These settings tell the CLI that we want to deploy all files in the ./public directory ( "public": "./public" ).

  1. Make sure that your command line is accessing your app's local web-start directory.
  2. Deploy your files to your Firebase project by running the following command: 
firebase deploy --except functions
  1. The console should display the following:
=== Deploying to 'friendlychat-1234'...

i  deploying firestore, storage, hosting
i  storage: checking storage.rules for compilation errors...
✔  storage: rules file storage.rules compiled successfully
i  firestore: checking firestore.rules for compilation errors...
✔  firestore: rules file firestore.rules compiled successfully
i  storage: uploading rules storage.rules...
i  firestore: uploading rules firestore.rules...
i  hosting[friendlychat-1234]: beginning deploy...
i  hosting[friendlychat-1234]: found 8 files in ./public
✔  hosting[friendlychat-1234]: file upload complete
✔  storage: released rules storage.rules to firebase.storage/friendlychat-1234.appspot.com
✔  firestore: released rules firestore.rules to cloud.firestore
i  hosting[friendlychat-1234]: finalizing version...
✔  hosting[friendlychat-1234]: version finalized
i  hosting[friendlychat-1234]: releasing new version...
✔  hosting[friendlychat-1234]: release complete

✔  Deploy complete!

Project Console: https://console.firebase.google.com/project/friendlychat-1234/overview
Hosting URL: https://friendlychat-1234.firebaseapp.com
  1. Visit your web app that's now fully hosted using Firebase Hosting at two of your very own Firebase subdomains:

Alternatively, you can run firebase open hosting:site in the command line.

Visit the documentation to learn more about how Firebase Hosting works.

Go to your project's Firebase console Hosting section to view useful hosting information and tools, including the history of your deploys, the functionality to roll back to previous versions of your app, and the workflow to set up a custom domain.

Cloud Functions allows you to easily have code that runs in the Cloud without having to setup a server. We'll be showing you how to build functions that react to Firebase Auth, Cloud Storage and Firebase Realtime Database events. Let's start with Auth.

When using the Firebase SDK for Cloud Functions, your Functions code will live under the functions directory (by default). Your Functions code is also a Node.js app and therefore needs a package.json that gives some information about your app and lists dependencies.

To make it easier for you we've already created the functions/index.js file where your code will go. Feel free to inspect this file before moving forward. 

cd functions
ls

If you are not familiar with Node.js it will help to learn more about it before continuing the codelab.

The package.json file already lists two required dependencies: the Firebase SDK for Cloud Functions and the Firebase Admin SDK. To install them locally run npm install from the functions folder: 

npm install

Let's now have a look at the index.js file:

index.js

/**
 * Copyright 2017 Google Inc. All Rights Reserved.
 * ...
 */

// TODO(DEVELOPER): Import the Cloud Functions for Firebase and the Firebase Admin modules here.

// TODO(DEVELOPER): Write the addWelcomeMessage Function here.

// TODO(DEVELOPER): Write the blurImages Function here.

// TODO(DEVELOPER): Write the sendNotification Function here.

We'll first import the required modules and then write three Functions in place of the TODOs. First let's import the required Node modules.

Two modules will be required during this codelab, the firebase-functions module allows us to write the Cloud Functions trigger rules, while the firebase-admin module allows us to use the Firebase platform on a server with admin access, for instance to write to the Cloud Firestore or send FCM notifications.

In the index.js file, replace the first TODO with the following:

index.js

/**
 * Copyright 2017 Google Inc. All Rights Reserved.
 * ...
 */

// Import the Firebase SDK for Google Cloud Functions.
const functions = require('firebase-functions');
// Import and initialize the Firebase Admin SDK.
const admin = require('firebase-admin');
admin.initializeApp();

// TODO(DEVELOPER): Write the addWelcomeMessage Function here.

// TODO(DEVELOPER): Write the blurImages Function here.

// TODO(DEVELOPER): Write the sendNotification Function here.

The Firebase Admin SDK can be configured automatically when deployed on a Cloud Functions environment or other Google Cloud Platform containers. This is what we do above when calling admin.initializeApp();

Now let's add a Function that runs when a user signs in for the first time in your chat app and we'll add a chat message to welcome the user.

Chat messages structure

Messages posted to the FriendlyChat chat feed are stored in the Cloud Firestore. Let's have a look at the data structure we use for a message. To do this, post a new message to the chat that reads "Hello World":

This should appear as:

In your Firebase app console click on Database under the Develop section. You should see the messages collection and one document containing the message that you wrote:

As you can see, chat messages are stored in the Cloud Firestore as a document with the name, profilePicUrl, text and timestamp attributes added to the messages collection.

Adding welcome messages

The first Cloud Function adds a message that welcomes new users into the chat. For this we can use the trigger functions.auth().onCreate which runs the function every time a user signs-in for the first time in your Firebase app. Add the addWelcomeMessages function into your index.js file:

index.js

// Adds a message that welcomes new users into the chat.
exports.addWelcomeMessages = functions.auth.user().onCreate(async (user) => {
  console.log('A new user signed in for the first time.');
  const fullName = user.displayName || 'Anonymous';

  // Saves the new welcome message into the database
  // which then displays it in the FriendlyChat clients.
  await admin.firestore().collection('messages').add({
    name: 'Firebase Bot',
    profilePicUrl: '/images/firebase-logo.png', // Firebase logo
    text: `${fullName} signed in for the first time! Welcome!`,
    timestamp: admin.firestore.FieldValue.serverTimestamp(),
  });
  console.log('Welcome message written to database.');
});

Adding this function to the special exports object is Node's way of making the function accessible outside of the current file and is required for Cloud Functions.

In the function above we are adding a new welcome message posted by "Firebase Bot" to the list of chat messages. We are doing this by using the add method on the messages collection in the Cloud Firestore which is where the messages of the chat are stored.

Since this is an asynchronous operation, we need to return the Promise indicating when the Cloud Firestore write has finished, so that Functions doesn't exit the execution too early.

Deploy the Function

The Function will only be active after you've deployed it. On the command line run firebase deploy --only functions: 

firebase deploy --only functions

This is the console output you should see:

i  deploying functions
i  functions: ensuring necessary APIs are enabled...
⚠  functions: missing necessary APIs. Enabling now...
i  env: ensuring necessary APIs are enabled...
⚠  env: missing necessary APIs. Enabling now...
i  functions: waiting for APIs to activate...
i  env: waiting for APIs to activate...
✔  env: all necessary APIs are enabled
✔  functions: all necessary APIs are enabled
i  functions: preparing functions directory for uploading...
i  functions: packaged functions (X.XX KB) for uploading
✔  functions: functions folder uploaded successfully
i  starting release process (may take several minutes)...
i  functions: creating function addWelcomeMessages...
✔  functions[addWelcomeMessages]: Successful create operation.
✔  functions: all functions deployed successfully!

✔  Deploy complete!

Project Console: https://console.firebase.google.com/project/friendlypchat-1234/overview

Test the function

Once the function has deployed successfully you'll need to have a user that signs in for the first time.

  1. Open your app in your browser using the hosting URL (in the form of https://<project-id>.firebaseapp.com).
  2. With a new user, sign in for the first time in your app using the Sign In button.

  1. After you sign in, a welcome message should be displayed automatically:

To deploy the whole project (static files, functions, rules...), go back to the web-start folder and run firebase deploy: 

firebase deploy

This is the console output you should see:

i  deploying storage, firestore, functions, hosting
i  storage: checking storage.rules for compilation errors...
✔  storage: rules file storage.rules compiled successfully
i  firestore: checking firestore.rules for compilation errors...
✔  firestore: rules file firestore.rules compiled successfully
i  functions: ensuring necessary APIs are enabled...
✔  functions: all necessary APIs are enabled
i  storage: uploading rules storage.rules...
i  firestore: uploading rules firestore.rules...
i  functions: preparing functions directory for uploading...
i  functions: packaged functions (36.16 KB) for uploading
✔  functions: functions folder uploaded successfully
i  hosting[friendlychat-1234]: beginning deploy...
i  hosting[friendlychat-1234]: found 7 files in ./public
✔  hosting[friendlychat-1234]: file upload complete
✔  storage: released rules storage.rules to firebase.storage/friendlychat-1234.appspot.com
✔  firestore: released rules firestore.rules to cloud.firestore
i  functions: updating Node.js 8 function addWelcomeMessages(us-central1)...
✔  functions[addWelcomeMessages(us-central1)]: Successful update operation. 
i  hosting[friendlychat-1234]: finalizing version...
✔  hosting[friendlychat-1234]: version finalized
i  hosting[friendlychat-1234]: releasing new version...
✔  hosting[friendlychat-1234]: release complete

✔  Deploy complete!

Project Console: https://console.firebase.google.com/project/friendlychat-1234/overview
Hosting URL: https://friendlychat-1234.firebaseapp.com

Open the web app

The last line should display the Hosting URL. The web app should now be served from this URL which should be of the form https://<project-id>.firebaseapp.com. Open it. You should see a chat app's functioning UI.

Sign-in to the app by using the SIGN-IN WITH GOOGLE button and feel free to add some messages:

We'll now add a feature that shares images.

While the Cloud Firestore is good for storing structured data, Cloud Storage is better suited for storing files. Cloud Storage for Firebase is a file/blob storage service, and we'll use it to store any images that a user shares using our app.

Save images to Cloud Storage

For this codelab, we've already added for you a button that triggers a file picker dialog. After selecting a file, the saveImageMessage function is called, and you can get a reference to the selected file. The saveImageMessage function accomplishes the following:

  1. Creates a "placeholder" chat message in the chat feed, so that users see a "Loading" animation while we upload the image.
  2. Uploads the image file to Cloud Storage to this path: /<uid>/<messageId>/<file_name>
  3. Generates a publicly readable URL for the image file.
  4. Updates the chat message with the newly uploaded image file's URL in lieu of the temporary loading image.

Now you'll add the functionality to sned an image:

  1. Go back to the file public/scripts/main.js.
  2. Find the function saveImageMessage.
  3. Replace the entire function with the following code.

main.js 

// Saves a new message containing an image in Firebase.
// This first saves the image in Firebase storage.
function saveImageMessage(file) {
  // 1 - We add a message with a loading icon that will get updated with the shared image.
  firebase.firestore().collection('messages').add({
    name: getUserName(),
    imageUrl: LOADING_IMAGE_URL,
    profilePicUrl: getProfilePicUrl(),
    timestamp: firebase.firestore.FieldValue.serverTimestamp()
  }).then(function(messageRef) {
    // 2 - Upload the image to Cloud Storage.
    var filePath = firebase.auth().currentUser.uid + '/' + messageRef.id + '/' + file.name;
    return firebase.storage().ref(filePath).put(file).then(function(fileSnapshot) {
      // 3 - Generate a public URL for the file.
      return fileSnapshot.ref.getDownloadURL().then((url) => {
        // 4 - Update the chat message placeholder with the image's URL.
        return messageRef.update({
          imageUrl: url,
          storageUri: fileSnapshot.metadata.fullPath
        });
      });
    });
  }).catch(function(error) {
    console.error('There was an error uploading a file to Cloud Storage:', error);
  });
}

Test sending images

  1. If your app is still being served, refresh your app in the browser. Otherwise, run firebase serve --only hosting on the command line to start serving the app from http://localhost:5000, and then open it in your browser.
  2. After signing in, click the image upload button and select an image file using the file picker. If you're looking for an image, feel free to use this nice picture of a coffee cup.
  3. A new message should appear in the app's UI with your selected image:

If you try adding an image while not signed in, you should see a Toast notification telling you that you must sign in to add images.

We'll now add support for browser notifications. The app will notify users when new messages are posted in the chat. Firebase Cloud Messaging (FCM) is a cross-platform messaging solution that lets you reliably deliver messages and notifications at no cost.

Whitelist the GCM Sender ID

In the web app manifest, you need to specify the gcm_sender_id, which is a hard-coded value indicating that FCM is authorized to send messages to this app.

  1. From the web-start directory, in the public directory, open manifest.json.
  2. Add the browser sender ID value in the gcm_sender_id attribute exactly as shown below. Do not change the value from what's shown below.

manifest.json 

{
  "name": "Friendly Chat",
  "short_name": "Friendly Chat",
  "start_url": "/index.html",
  "display": "standalone",
  "orientation": "portrait",
  "gcm_sender_id": "103953800507"
}

Add the FCM service worker

The web app needs a service worker that will receive and display web notifications.

  1. From the web-start directory, in the public directory, create a new file named firebase-messaging-sw.js.
  2. Add the following content to that new file.

firebase-messaging-sw.js 

importScripts('/__/firebase/6.0.4/firebase-app.js');
importScripts('/__/firebase/6.0.4/firebase-messaging.js');
importScripts('/__/firebase/init.js');

firebase.messaging();

The service worker simply needs to load and initialize the Firebase Cloud Messaging SDK, which will take care of displaying notifications.

Get FCM device tokens

When notifications have been enabled on a device or browser, you'll be given a device token. This device token is what we use to send a notification to a particular device or particular browser.

When the user signs-in, we call the saveMessagingDeviceToken function. That's where we'll get the FCM device token from the browser and save it to Cloud Firestore.

  1. Go back to the file public/scripts/main.js.
  2. Find the function saveMessagingDeviceToken.
  3. Replace the entire function with the following code.

main.js 

// Saves the messaging device token to the datastore.
function saveMessagingDeviceToken() {
  firebase.messaging().getToken().then(function(currentToken) {
    if (currentToken) {
      console.log('Got FCM device token:', currentToken);
      // Saving the Device Token to the datastore.
      firebase.firestore().collection('fcmTokens').doc(currentToken)
          .set({uid: firebase.auth().currentUser.uid});
    } else {
      // Need to request permissions to show notifications.
      requestNotificationsPermissions();
    }
  }).catch(function(error){
    console.error('Unable to get messaging token.', error);
  });
}

However, this code won't work initially. For your app to be able to retrieve the device token, the user needs to grant your app permission to show notifications (next step of the codelab).

Request permissions to show notifications

When the user has not yet granted your app permission to show notifications, you won't be given a device token. In this case, we call the firebase.messaging().requestPermission() method, which will display a browser dialog asking for this permission (in supported browsers).

  1. Go back to the file public/scripts/main.js.
  2. Find the function requestNotificationsPermissions.
  3. Replace the entire function with the following code.

main.js 

// Requests permission to show notifications.
function requestNotificationsPermissions() {
  console.log('Requesting notifications permission...');
  firebase.messaging().requestPermission().then(function() {
    // Notification permission granted.
    saveMessagingDeviceToken();
  }).catch(function(error) {
    console.error('Unable to get permission to notify.', error);
  });
}

Get your device token

  1. If your app is still being served, refresh your app in the browser. Otherwise, run firebase serve on the command line to start serving the app from http://localhost:5000, and then open it in your browser.
  2. After signing in, the notifications permission dialog should appear:
  3. Click Allow.
  4. Open the JavaScript console of your browser. You should see the following message:
    Got FCM device token: cWL6w:APA91bHP...4jDPL_A-wPP06GJp1OuekTaTZI5K2Tu
  5. Copy your device token. You'll need it for the next stage of the codelab.

Send a notification to your device

Now that you have your device token, you can send a notification.

  1. In addition to the device token, you'll also need your Firebase app's Server Key. To obtain this key, go to Firebase Console > Project Settings > Cloud Messaging, then copy the Server Key.

To send a notification, you'll need to send the following HTTP request: 

POST /fcm/send HTTP/1.1
Host: fcm.googleapis.com
Content-Type: application/json
Authorization: key=YOUR_SERVER_KEY

{
  "notification": {
    "title": "New chat message!",
    "body": "There is a new message in FriendlyChat",
    "icon": "/images/profile_placeholder.png",
    "click_action": "http://localhost:5000"
  },
  "to":"YOUR_DEVICE_TOKEN"
}
  1. On the command line, run the following cURL command. 
curl -H "Content-Type: application/json" \
     -H "Authorization: key=YOUR_SERVER_KEY" \
     -d '{
           "notification": {
             "title": "New chat message!",
             "body": "There is a new message in FriendlyChat",
             "icon": "/images/profile_placeholder.png",
             "click_action": "http://localhost:5000"
           },
           "to": "YOUR_DEVICE_TOKEN"
         }' \
     https://fcm.googleapis.com/fcm/send

Note that the notification will only appear if the FriendlyChat app is in the background. You must navigate away or display another tab for the notification to be displayed. When the app is in the foreground, there is a way to catch the messages sent by FCM.

If your app is in the background, a notification should appear in your browser, as in this example:

In this section you will add a Cloud Function that sends notifications to participants of the chat when a new message is posted.

Using Firebase Cloud Messaging (FCM) you can send notifications to your users in a cross platform and reliable way. To send a notification to a user you need their FCM device token. The chat web app that we are using already collects device tokens from users when they open the app for the first time on a new browser or device. These tokens are stored in Cloud Firestore in the fcmTokens collection.

Send notifications

To detect when new messages are posted you'll be using the functions.firestore.document().onCreate Cloud Functions trigger which runs your code when a new object is created at a given path of the Cloud Firestore. Add the sendNotifications function into your index.js file:

index.js

// Sends a notifications to all users when a new message is posted.
exports.sendNotifications = functions.firestore.document('messages/{messageId}').onCreate(
  async (snapshot) => {
    // Notification details.
    const text = snapshot.data().text;
    const payload = {
      notification: {
        title: `${snapshot.data().name} posted ${text ? 'a message' : 'an image'}`,
        body: text ? (text.length <= 100 ? text : text.substring(0, 97) + '...') : '',
        icon: snapshot.data().profilePicUrl || '/images/profile_placeholder.png',
        click_action: `https://${process.env.GCLOUD_PROJECT}.firebaseapp.com`,
      }
    };

    // Get the list of device tokens.
    const allTokens = await admin.firestore().collection('fcmTokens').get();
    const tokens = [];
    allTokens.forEach((tokenDoc) => {
      tokens.push(tokenDoc.id);
    });

    if (tokens.length > 0) {
      // Send notifications to all tokens.
      const response = await admin.messaging().sendToDevice(tokens, payload);
      await cleanupTokens(response, tokens);
      console.log('Notifications have been sent and tokens cleaned up.');
    }
  });

In the Function above we are gathering all users' device tokens from the Cloud Firestore Database and sending a notification to each of these using the admin.messaging().sendToDevice function.

Cleanup the tokens

Lastly we want to remove the tokens that are not valid anymore. This happens when the token that we once got from the user is not being used by the browser or device anymore. For instance, this happens if the user has revoked the notification permission for his browser session. To do this add the following cleanupTokens function in your index.js file:

index.js

// Cleans up the tokens that are no longer valid.
function cleanupTokens(response, tokens) {
 // For each notification we check if there was an error.
 const tokensDelete = [];
 response.results.forEach((result, index) => {
   const error = result.error;
   if (error) {
     console.error('Failure sending notification to', tokens[index], error);
     // Cleanup the tokens who are not registered anymore.
     if (error.code === 'messaging/invalid-registration-token' ||
         error.code === 'messaging/registration-token-not-registered') {
       const deleteTask = admin.firestore().collection('messages').doc(tokens[index]).delete();
       tokensDelete.push(deleteTask);
     }
   }
 });
 return Promise.all(tokensDelete);
}

Deploy the Function

The Function will only be active after you've deployed it. On the command line run firebase deploy --only functions: 

firebase deploy --only functions

This is the console output you should see:

i  deploying functions
i  functions: ensuring necessary APIs are enabled...
✔  functions: all necessary APIs are enabled
i  functions: preparing functions directory for uploading...
i  functions: packaged functions (X.XX KB) for uploading
✔  functions: functions folder uploaded successfully
i  starting release process (may take several minutes)...
i  functions: updating function addWelcomeMessages...
i  functions: updating function blurOffensiveImages...
i  functions: creating function sendNotifications...
✔  functions[addWelcomeMessages]: Successful update operation.
✔  functions[blurOffensiveImages]: Successful updating operation.
✔  functions[sendNotifications]: Successful create operation.
✔  functions: all functions deployed successfully!

✔  Deploy complete!

Project Console: https://console.firebase.google.com/project/friendlychat-1234/overview

Test the function

  1. Once the function has deployed successfully, open your app in your browser using the hosting URL (in the form of https://<project-id>.firebaseapp.com).
  2. If you sign-in the app for the first time make sure you allow notifications when prompted:
  3. Close the chat app tab or display a different tab: Notifications appear only if the app is in the background. If you would like to learn how to receive messages while your app is in the foreground have a look at our documentation.
  4. Using a different browser (or an Incognito window), sign into the app and post a message. You should see a notification displayed by the first browser:

You've used Firebase to build a real-time chat web application!

What we've covered

Learn more

In this section you will add a firebase extensions for automatically translate all texts.

Using Firebase Extensions With firebase extensions, you can install pre-packaged solutions for help you

We wan't to add a new fonctionnality for translate all messages into multiple languages and save it in the Cloud Firestore.

Install extension

Let's check the catalog of available extensions on the Firebase website.

Look at that! There's an extension called "Translate Text". That looks promising.

Let's use this extension in your app!

Install an extension

  1. Click See details to view more information about this extension. Under What you can configure, the extension lets you set the dimensions you'd like to resize to, and you can even set the cache header. Perfect!
  2. Click the Install in console button on the extension's details page. You will be taken to a Firebase console page which lists all of your projects.
  3. Choose your FriendlyChat project that you created for this codelab.
  4. Follow the on-screen instructions until you reach the Configure extension step.
    The instructions will show a basic summary of the extension, as well as any resources it will create and access roles it requires.
  5. In the Collection path field, enter the following:

messages

  1. In the Input field name field, enter the following:

text

  1. Leave the other parameters at their default values.
  2. Click Install extension.
  3. Wait for the installation.

Users can upload all type of images in the chat, and it is always important to moderate offensive images, especially in public social platforms. In FriendlyChat the images that are being published to the chat are stored into Google Cloud Storage.

With Cloud Functions, you can detect new image uploads using the functions.storage().onFinalize trigger. This will run every time a new file is uploaded or modified in Cloud Storage.

To moderate images we'll go through the following process:

  1. Check if the image is flagged as Adult or Violent using the Cloud Vision API
  2. If the image has been flagged, download it on the running Functions instance
  3. Blur the image using ImageMagick
  4. Upload the blurred image to Cloud Storage

Enable the Cloud Vision API

Since we'll be using the Google Cloud Vision API in this function, you must enable the API on your firebase project. Follow this link, select your Firebase project and enable the API:

Install dependencies

To moderate the images we'll need a few Node.js packages:

To install these two packages into your Cloud Functions app, run the following npm install --save command. Make sure that you do this from the functions directory. 

npm install --save @google-cloud/vision@0.12.0 child-process-promise@2.2.1

This will install the two packages locally and add them as declared dependencies in your package.json file.

Import and configure dependencies

To import the two dependencies that were installed and some Node.js core modules (path, os and fs) that we'll need in this section add the following lines to the top of your index.js file:

index.js

const Vision = require('@google-cloud/vision');
const vision = new Vision();
const spawn = require('child-process-promise').spawn;

const path = require('path');
const os = require('os');
const fs = require('fs');

Since your function will run inside a Google Cloud environment, there is no need to configure the Cloud Storage and Cloud Vision libraries: they will be configured automatically to use your project.

Detecting inappropriate images

You'll be using the functions.storage.onChange Cloud Functions trigger which runs your code as soon as a file or folder is created or modified in a Cloud Storage bucket. Add the blurOffensiveImages Function into your index.js file:

index.js

// Checks if uploaded images are flagged as Adult or Violence and if so blurs them.
exports.blurOffensiveImages = functions.runWith({memory: '2GB'}).storage.object().onFinalize(
    async (object) => {
      const image = {
        source: {imageUri: `gs://${object.bucket}/${object.name}`},
      };

      // Check the image content using the Cloud Vision API.
      const batchAnnotateImagesResponse = await vision.safeSearchDetection(image);
      const safeSearchResult = batchAnnotateImagesResponse[0].safeSearchAnnotation;
      const Likelihood = Vision.types.Likelihood;
      if (Likelihood[safeSearchResult.adult] >= Likelihood.LIKELY ||
          Likelihood[safeSearchResult.violence] >= Likelihood.LIKELY) {
        console.log('The image', object.name, 'has been detected as inappropriate.');
        return blurImage(object.name);
      }
      console.log('The image', object.name, 'has been detected as OK.');
    });

Note that we added some configuration of the Cloud Functions instance that will run the function, with .runWith({memory: '2GB'}) we're requesting that the instance gets 2GB of memory rather than the default, this will help as this function is memory intensive.

When the function is triggered, the image is ran through the Cloud Vision API to detect if it is flagged as adult or violent. If the image is detected as inappropriate based on these criteria we're blurring the image which is done in the blurImage function which we'll see next.

Blurring the image

Add the following blurImage function in your index.js file:

index.js

// Blurs the given image located in the given bucket using ImageMagick.
async function blurImage(filePath) {
  const tempLocalFile = path.join(os.tmpdir(), path.basename(filePath));
  const messageId = filePath.split(path.sep)[1];
  const bucket = admin.storage().bucket();

  // Download file from bucket.
  await bucket.file(filePath).download({destination: tempLocalFile});
  console.log('Image has been downloaded to', tempLocalFile);
  // Blur the image using ImageMagick.
  await spawn('convert', [tempLocalFile, '-channel', 'RGBA', '-blur', '0x24', tempLocalFile]);
  console.log('Image has been blurred');
  // Uploading the Blurred image back into the bucket.
  await bucket.upload(tempLocalFile, {destination: filePath});
  console.log('Blurred image has been uploaded to', filePath);
  // Deleting the local file to free up disk space.
  fs.unlinkSync(tempLocalFile);
  console.log('Deleted local file.');
  // Indicate that the message has been moderated.
  await admin.firestore().collection('messages').doc(messageId).update({moderated: true});
  console.log('Marked the image as moderated in the database.');
}

In the above function the image binary is downloaded from Cloud Storage. Then the image is blurred using ImageMagick's convert tool and the blurred version is re-uploaded on the Storage Bucket. Then we delete the file on the Cloud Functions instance to free up some disk space, we do this because the same Cloud Functions instance can get re-used and if files are not cleaned up it could run out of disk. Finally we add a boolean to the chat message indicating the image was moderated, this will trigger a refresh of the message on the client.

Deploy the Function

The Function will only be active after you've deployed it. On the command line run firebase deploy --only functions: 

firebase deploy --only functions

This is the console output you should see:

i  deploying functions
i  functions: ensuring necessary APIs are enabled...
✔  functions: all necessary APIs are enabled
i  functions: preparing functions directory for uploading...
i  functions: packaged functions (X.XX KB) for uploading
✔  functions: functions folder uploaded successfully
i  starting release process (may take several minutes)...
i  functions: updating function addWelcomeMessages...
i  functions: creating function blurOffensiveImages...
✔  functions[addWelcomeMessages]: Successful update operation.
✔  functions[blurOffensiveImages]: Successful create operation.
✔  functions: all functions deployed successfully!

✔  Deploy complete!

Project Console: https://console.firebase.google.com/project/friendlychat-1234/overview

Test the function

Once the function has deployed successfully:

  1. Open your app in your browser using the hosting URL (in the form of https://<project-id>.firebaseapp.com).
  2. Once signed-in the app upload an image:
  3. Choose your best offensive image to upload (or you can use this flesh eating Zombie!) and after a few moments you should see your post refresh with a blurred version of the image: