Implementing Firebase Cloud Messaging (FCM) HTTP v1 in PHP/Laravel

This article provides a practical guide to implementing Firebase Cloud Messaging (FCM) HTTP v1 in PHP or Laravel. With the introduction of the HTTP v1 API, FCM has enhanced security and expanded capabilities. As the legacy FCM API will be deprecated by June 20, 2024, this guide is essential for those looking to implement or migrate to the new HTTP v1 API in PHP.

Prerequisites

1. Service Account Key: Ensure you have a service account JSON key file for your Firebase project. You can generate this from the Firebase Console under Project Settings > Service Accounts > Generate New Private Key.

2. Google Client Library: Verify that the google/apiclient package is installed. If it's not, you can install it using Composer:

    composer require google/apiclient
   

Notification Service

<?php

namespace App\Services;

use App\Models\FcmToken;
use App\Models\Notification;
use Exception;
use Google\Client;

class NotificationService
{
    public function store(array $data)
    {
        try {
            Notification::create([
                'title' => $data['title'],
                'content' => $data['content'],
                'user_id' => $data['user_id'],
            ]);

            $message = [
                'token' => $data['token'],
                'notification' => [
                    'title' => $data['title'],
                    'body' => $data['content'],
                ],
                'data' => $data['additional'],
            ];

            $token = $this->getAccessToken(storage_path('YOUR_SERVICE_ACCOUNT_KEY_JSON_PATH'));
            $this->sendMessage($token, 'YOUR_PROJECT_ID', $message);

            return true;
        } catch (\Throwable $th) {
            throw $th;
        }
    }

    function getAccessToken($serviceAccountPath)
    {
        $client = new Client();
        $client->setAuthConfig($serviceAccountPath);
        $client->addScope('https://www.googleapis.com/auth/firebase.messaging');
        $client->useApplicationDefaultCredentials();
        $token = $client->fetchAccessTokenWithAssertion();
        return $token['access_token'];
    }

    function sendMessage($accessToken, $projectId, $message = [])
    {
        $url = 'https://fcm.googleapis.com/v1/projects/' . $projectId . '/messages:send';
        $headers = [
            'Authorization: Bearer ' . $accessToken,
            'Content-Type: application/json',
        ];
        $ch = curl_init();
        curl_setopt($ch, CURLOPT_URL, $url);
        curl_setopt($ch, CURLOPT_POST, true);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
        curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
        curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode(['message' => $message]));
        $response = curl_exec($ch);
        if ($response === false) {
            throw new Exception('Curl error: ' . curl_error($ch));
        }
        curl_close($ch);
        return json_decode($response, true);
    }
}

The NotificationService class is responsible for storing notifications in the database and sending them to a user's device using Firebase Cloud Messaging (FCM).

1. Storing the Notification: The store method first creates a new notification record in the database using the Notification model. It stores the title, content, and user_id fields from the $data array.

2. Preparing the FCM Message: The method then constructs an $message array, which includes the recipient device's FCM token, a notification an array containing the title and body, and any additional data.

3. Getting the Access Token: To send the message through FCM, the method calls getAccessToken, passing the path to the Firebase service account JSON file. This method uses Google's Client class to authenticate with Firebase, add the necessary scope for Firebase Messaging, and fetch an access token.

4. Sending the FCM Message: With the access token retrieved, the sendMessage method is called to send the message. It constructs the API request using cURL, sets the required headers (including the authorization token), and sends the message to FCM via a POST request. If the request is successful, the response from FCM is decoded and returned.

5. Error Handling: The entire store method is wrapped in a try-catch block to handle any potential errors that may occur during the notification creation or sending process. If an error occurs, it is re-thrown for further handling.