Firebase remote config condition by userId

Question

I integrated Firebase into my Android project, to get a different parameter value for different application user. I did the following:

1. Setup users in my Firebase Project
2. Created audiences to match the users: UIDs were AAAAAAA..., and BBBBBBB... accordingly.
3. Created a parameter in Remote Config section:
4. Added conditions for this parameter: and set values for the conditions:

5. Entered the following code to sign in the user from the application:

   Task resultTask =   
       firebaseAuth.signInWithEmailAndPassword("[email protected]", password);

6. Made sure sign in was successful.
7. Then I tried to fetch the remote config parameter:

   firebaseRemoteConfig.fetch() 
                   .addOnCompleteListener(new OnCompleteListener() {
                       @Override
                       public void onComplete(@NonNull Task task) {
                           if (task.isSuccessful()) {
                               // Once the config is successfully fetched it must be activated before newly fetched
                               // values are returned.
                               firebaseRemoteConfig.activateFetched();
                               Log.d(TAG, firebaseRemoteConfig.getString("MyParameter"));
                           } else {
                               Log.d(TAG, "fetch firebase remote config failed. Reason = " + task.getException());
                           }
                       }
                   });

The result was that I always got the default value: DefaultValue

What did I do wrong? What did I miss?

Answer 1

After some investigation I figured that Firebase Analytics and Firebase Authentication are 2 different modules which don't automatically inter-connect.

Using Firebase Authentication did not automatically identify the user as part of the particular audience, as I expected.

I needed to tell Firebase Analytics, that the current user has the specific user ID, so it can match it to the relevant audience. I added the following code to the sign-in onComplete callback:

Task<AuthResult> resultTask =   
    firebaseAuth.signInWithEmailAndPassword("[email protected]", password); 
resultTask.addOnCompleteListener(new OnCompleteListener<AuthResult>() {
        @Override
        public void onComplete(@NonNull Task<AuthResult> task) {
            // Task completed successfully
            if (task.isSuccessful()) {
               firebaseAnalytics.setUserId(task.getResult().getUser().getUid());
            } else {
                Log.d(TAG, "signInWithEmail firebase failed");
            }
        }
    });

The important line is:

firebaseAnalytics.setUserId(task.getResult().getUser().getUid());

Some things to note:

1. Once a user is in an audience it can never exit the audience, which means, if you change the user in the app from the same device, you will get a match to 2 audiences: The new audience, and the previous one.
2. While testing this I had to fetch the remote config parameter very frequently. Although I set the cache expiration to 0, I had a different problem: The Firebase server responded sometime with throttling exception. So, while testing make sure not to throttle the server or you'll have to wait a long time between tests.
3. I'm not sure, but it seams that Firebase Analytics keeps track of the app user with a different id then the one defined with Firebase Authentication. I think, this is why if you sign-in with different user id in Firebase Authentication from the same device, you still match to the audience that was setup for the previuos Firebase user ID.