Google Sign-In in Jetpack Compose

Documentation

Overview

This documentation provides guidance on implementing Google Sign-In in a Jetpack Compose application. The provided code demonstrates the integration of Google Sign-In using the Google Sign-In API and Firebase Authentication.

Prerequisites

Before implementing Google Sign-In, make sure you have the following:

1. A Google Cloud Platform (GCP) project with the necessary credentials.
2. Firebase project set up with Firebase Authentication.

Implementation Steps

1. Add Dependencies

Ensure you have the required dependencies in your build.gradle file:

implementation "androidx.activity:activity-compose:1.3.0-alpha08"
implementation "com.google.android.gms:play-services-auth:19.0.0"
implementation "com.google.firebase:firebase-auth:23.0.0"

2. Add Google Services Configuration

Add the google-services.json file to your app module. This file contains configuration details for your Firebase project.

3. Get Web Client ID

Ensure that you include your web client ID as well. You can obtain it from the Firebase Console by navigating to Authentication > Sign-in Method > Google > Web SDK Implementation.

4. Add Google Sign-In Launcher

Add Google Sign-in Launcher inside a composable:

@Composable
fun SignInScreen() {
    // Initialize the Google Sign-In launcher using the ActivityResultContracts
    val googleSignInLauncher =
        rememberLauncherForActivityResult(contract = ActivityResultContracts.StartActivityForResult()
    ) { result ->
        if (result.resultCode == Activity.RESULT_OK) {
            val task = GoogleSignIn.getSignedInAccountFromIntent(result.data)
            handleSignInResult(task, context)
        }
    }

    // ... (Your existing code)
}

5. Add Google Sign-in Function

Implement a function to initiate Google Sign-in:

fun signInWithGoogle(
    googleSignInLauncher: ManagedActivityResultLauncher<Intent, ActivityResult>,
    context: Context
) {
    val webClientID = "YOUR_WEB_CLIENT_ID"
    val googleSignInOptions = GoogleSignInOptions
        .Builder(GoogleSignInOptions.DEFAULT_SIGN_IN)
        .requestIdToken(webClientID)
        .requestEmail()
        .build()
    val googleSignInClient = GoogleSignIn.getClient(context, googleSignInOptions)
    // hack-ish way to re-select google account during sign-in
    googleSignInClient.signOut()
    val signInIntent = googleSignInClient.signInIntent
    googleSignInLauncher.launch(signInIntent)
}

6. Add Handle Sign-in Result Function

Implement the function to handle the result of Google Sign-In:

fun handleSignInResult(completedTask: Task<GoogleSignInAccount>, context: Context) {
    try {
        val account = completedTask.getResult(ApiException::class.java)
        firebaseAuthWithGoogle(account.idToken!!, context)
    } catch (e: ApiException) {
        toast("Error: ${e.statusCode} ${e.message}", context)
    }
}

7. Add Firebase Authentication

Implement the function for Firebase Authentication using the obtained Google Sign-In account:

private fun firebaseAuthWithGoogle(idToken: String?, context: Context) {
    val auth: FirebaseAuth = FirebaseAuth.getInstance()
    val credential = GoogleAuthProvider.getCredential(idToken, null)

    auth.signInWithCredential(credential)
        .addOnCompleteListener { task ->
            if (task.isSuccessful) {
                // get email from currently signed-in user
                val email = auth.currentUser?.email ?: ""
                toast("Your email: $email", context)
            } else {
                toast("Failed to sign-in", context)
            }
        }
}

Screenshot