How to work with FirebaseAuth inside Android Module

Question

I am developing a Chat library in which I want to show the conversations of the logged in user. The reason to make the library is that I want to integrate it in multiple projects.

The problem I am facing right now is that FirebaseAuth is indicating that the user is not logged-in (FirebaseAuth.getInstance(mFirebaseApp).getCurrentUser() always returning null) even if the user is authenticated inside the app.

How the Module/Library can know that the user is authenticated?

I am trying the following code:

mAPIKey = getArguments().getString(ConversationModuleConstants.API_KEY_KEY);
        mApplicatoinId = getArguments().getString(ConversationModuleConstants.APPLICATION_ID_KEY);
        mDatabaseUrl = getArguments().getString(ConversationModuleConstants.DATABASE_URL_KEY);

        FirebaseOptions options = new FirebaseOptions.Builder()
                .setApiKey(mAPIKey)
                .setApplicationId(mApplicatoinId)
                .setDatabaseUrl(mDatabaseUrl)
                .build();

        boolean hasBeenInitialized = false;
        List<FirebaseApp> firebaseApps = FirebaseApp.getApps(getActivity());
        for (FirebaseApp app : firebaseApps) {
            if (app.getName().equals(FIREBASE_APP_NAME)) {
                hasBeenInitialized = true;
                mFirebaseApp = app;
            }
        }

        if (!hasBeenInitialized) {
            mFirebaseApp = FirebaseApp.initializeApp(getActivity(), options, FIREBASE_APP_NAME);
        }

 if (FirebaseAuth.getInstance(mFirebaseApp).getCurrentUser() == null) {
            Toast.makeText(getActivity(), "Login Required!", Toast.LENGTH_SHORT).show();
            return;
        }

Answer 1

You need to add a listener/Observer to get the userid for every auth state change.

FirebaseAuth.getInstance().addAuthStateListener(firebaseAuth -> {
            if (firebaseAuth.getCurrentUser() == null) {
                your code goes here
            }
        });

https://firebase.google.com/docs/auth/android/manage-users

Another method wkile login get the user id and store in LocalStorage, while logout clear the localstorage, so that you will be able to maintain in offline too.

Answer 2

In Android, FirebaseApp object manages the configuration for all the Firebase APIs. This is initialized automatically by a content provider when your app is launched, and you typically never need to interact with it. However, when you want to access multiple projects from a single app, you'll need a distinct FirebaseApp to reference each one individually.

Before initializing your second project, make sure Firebase defaultApp instance is initialized. Call FirebaseDatabase.getInstance() from your base/main project's Application class - OnCreate() as below,

// Primary project database
FirebaseDatabase database = FirebaseDatabase.getInstance();

To connect second project database from your library project, initialize FirebaseApp with secondary configuration along with some distinct identifier(eg:"secondary") as below,

FirebaseOptions options = new FirebaseOptions.Builder()
       .setApplicationId("1:530266078999:android:481c4ecf3253701e") // Required for Analytics.
       .setApiKey("AIzaSyBRxOyIj5dJkKgAVPXRLYFkdZwh2Xxq51k") // Required for Auth.
       .setDatabaseUrl("https://project-1765055333176374514.firebaseio.com/") // Required for RTDB.
       .build();
FirebaseApp.initializeApp(this /* Context */, options, "secondary");

Then retrive the secound App

// Retrieve the second app.
FirebaseApp secondApp = FirebaseApp.getInstance("secondary");
// Get the database of second app.
FirebaseDatabase secondaryDatabase = FirebaseDatabase.getInstance(secondApp);

Note: Inside your library module, make sure you always refer your second project. Better create a singleton reference

// Make singleton reference
public static FirebaseApp getFirebaseApp() {
    if (mFirebaseApp == null) {
        Context context = getAppContext();
        FirebaseOptions options = getLibraryModuleFirebaseOptions();
        mFirebaseApp = FirebaseApp.initializeApp(context, options, "library");
    }
    return mFirebaseApp;
} 

For detailed information, please refer the Firebase blog post here

Hope this would help you..