Get Started with Firebase Realtime Database for C++

The Firebase Realtime Database stores and synchronizes data using a NoSQL cloud database. Data is synchronized across all clients in realtime, and remains available when your app goes offline.

Before You Begin

Before you can use Firebase Realtime Database, you need to:

Register your C++ project and configure it to use Firebase.

If your C++ project already uses Firebase, then it's already registered and configured for Firebase.
In your project-level build.gradle file, make sure to include Google's Maven repository in both your buildscript and allprojects sections.
Add the Firebase C++ SDK to your C++ project.

Note that adding Firebase to your C++ project involves tasks both in the Firebase console and in your open C++ project (for example, you download Firebase config files from the console, then move them into your C++ project).

Create a Database

If you haven't already, create a Firebase project: In the Firebase console, click Add project, then follow the on-screen instructions to create a Firebase project or to add Firebase services to an existing GCP project.
Navigate to the Database section of the Firebase console. You'll be prompted to select an existing Firebase project. Follow the database creation workflow.
Select a starting mode for your Firebase Security Rules:

Test mode

Good for getting started with the mobile and web client libraries, but allows anyone to read and overwrite your data. After testing, make sure to review the Understand Firebase Realtime Database Rules section.

To get started with the web, iOS, or Android SDK, select test mode.

Locked mode

Denies all reads and writes from mobile and web clients. Your authenticated application servers can still access your database.
Click Done.

When you enable Realtime Database, it also enables the API in the Cloud API Manager.

Create and Initialize firebase::App

Before you can access the Realtime Database, you'll need to create and initialize the firebase::App.

Include the header file for firebase::App:

#include "firebase/app.h"

Android

Create the firebase::App, passing the JNI environment and a jobject reference to the Java Activity as arguments:

app = ::firebase::App::Create(::firebase::AppOptions("APPLICATION NAME"), jni_env, activity);

iOS

Create the firebase::App:

app = ::firebase::App::Create(::firebase::AppOptions("APPLICATION NAME"));

Access the firebase::database::Database Class

The firebase::database::Database is the entry point for the Firebase Realtime Database C++ SDK.

::firebase::database::Database *database = ::firebase::database::Database::GetInstance(app);

If you have chosen to use public access for your rules, you can proceed to the sections on saving and retrieving data.

Setting up Restricted Access

If you do not want to use public access you can add Firebase Authentication to your app to control access to the database.

Next Steps

Learn how to structure data for Realtime Database.
Scale your data across multiple database instances.
Save data.
Retrieve data.
View your database in the Firebase console.
Prepare to launch your app:
- Set up budget alerts for your project in the GCP console.
- Monitor your Usage and billing dashboard in the Firebase console. You can also monitor your Realtime Database Usage dashboard.
- Review the Firebase launch checklist.

Known Issues

On desktop platforms (Windows, Mac, Linux), the Firebase C++ SDK uses REST to access your database. Because of this, you must declare the indexes you use with Query::OrderByChild() on desktop or your listeners will fail.
The desktop workflow version of Realtime Database does not support offline or persistence.