Connect to multiple Firebase DB

Question

My flutter app needs to connect to multiple firebase databases. the vision is that the user will start the application and will enter Firebase parameters and click "Connect". I find the following source lines

FirebaseApp app;
  Future<FirebaseApp> FBDB() async {
    WidgetsFlutterBinding.ensureInitialized();
    final FirebaseApp app = await FirebaseApp.configure(
      name: "FB.AAA.com", // "package_name"
      options: const FirebaseOptions(
        googleAppID: "1:79046:android:2fb2895a41bde78da062d",
        // "mobilesdk_app_id"
        gcmSenderID: "???",
        //"project_number":
        apiKey: "AIzamVHoX0C_zimD3UhUITF4ml7Be4fsI",
        //  "api_key": [ { "current_key"
        projectID: "fb-b64d", //"project_id"
      ),
    );
  }

The Google Services file is (changed the data):

{
  "project_info": {
    "project_number": "123",
    "firebase_url": "https://fb-b64d.firebaseio.com",
    "project_id": "fb-b64d",
    "storage_bucket": "fb-b64d.appspot.com"
  },
  "client": [
    {
      "client_info": {
        "mobilesdk_app_id": "1:79046:android:2fb2895a41bde78da062d",
        "android_client_info": {
          "package_name": "FB.AAA.com"
        }
      },
      "oauth_client": [
        {
          "client_id": "123-5555.apps.googleusercontent.com",
          "client_type": 3
        }
      ],
      "api_key": [
        {
          "current_key": "AIzamVHoX0C_zimD3UhUITF4ml7Be4fsI"
        }
      ],
      "services": {
        "appinvite_service": {
          "other_platform_oauth_client": [
            {
              "client_id": "793081656-5555.apps.googleusercontent.com",
              "client_type": 3
            }
          ]
        }
      }
    }
  ],
  "configuration_version": "1"
}

The result of the source code above is null (the object was not created) so my questions are:

1. Did I take the right parameters from the google Json file to the source code above? what should be in the gcmSenderID?

2. what is the next step? how should I receive the

   final FirebaseAuth _firebaseAuth = FirebaseAuth.instance
   

   In order to start query the DB?

Answer 1

If you want to get a Firebase service for a specific FirebaseApp instance, you pass that app into the service's constructor or call a factory method.

For example:

FirebaseDatabase(app: this.app).reference();

For for auth:

FirebaseAuth.fromApp(app)