Google SignIn in react-native using firebase auth

If you're looking for a solution without firebase, I've a medium article for that: https://medium.com/@ibjects/google-signin-tutorial-for-react-native-81a57fb67b18

Straight-forward way of implementing a google sign-in in a react native app using firebase.

Firebase Console

Add Google from the Additional Providers.

Note down your Web client ID.

Once it's done it should look like:

React-Native

Let's install the required libraries:

yarn add @react-native-firebase/app @react-native-firebase/auth
yarn add @react-native-google-signin/google-signin

Create a Login.tsx screen. There are a few things that work together here:

1. Checking onAuthStatusChanged using auth from @react-native-firebase/auth to check the current status of the user authentication.
2. Configure GoogleSignin using GoogleSignin.configure where we'll provide webClientId which you should have at the time of the firebase console side configuration.
3. Handle onGoogleButtonPress and renderGoogleSigninButton as we'll be creating our own button to trigger a GoogleSignin request.
4. Once a user is logged in then rendering a renderLogoutView and return main components.

Below is the code for Login.tsx broken down as per the number list above:

// 1. 

import auth, { FirebaseAuthTypes } from '@react-native-firebase/auth';

// other imports and code

    const [user, setUser] = React.useState<FirebaseAuthTypes.User | null>();

    function onAuthStatusChanged(user: FirebaseAuthTypes.User | null) {
        setUser(user);
    }

    useEffect(() => {
        const subscriber = auth().onAuthStateChanged(onAuthStatusChanged);
        return subscriber; // unsubscribe on unmount
    }, []);

// 2. 

import { GoogleSignin } from "@react-native-google-signin/google-signin";

//... other imports and everything in 1.

    GoogleSignin.configure({
        webClientId: 'ADD_YOUR_KEY_HERE',
        offlineAccess: true,
    });

If required, look for Web client ID reference above to know where to get it.

// 3a. onGoogleButtonPress

    async function onGoogleButtonPress() {
        if (user) {
            // user is already logged in so no need to do anything
            return null;
        }

        try {
            // Check if your device supports Google Play
            await GoogleSignin.hasPlayServices({ showPlayServicesUpdateDialog: true });
            // Get the users ID token
            const { idToken, user, serverAuthCode } = await GoogleSignin.signIn(); // returns type: User
            const { id, name, email, photo, familyName, givenName } = user;

            console.log('serverAuthCode: ', serverAuthCode);
            console.log('idToken: ', idToken);

            // Create a Google credential with the token
            const googleCredential = auth.GoogleAuthProvider.credential(idToken);

            // Sign-in the user with the credential
            return auth().signInWithCredential(googleCredential);
        } catch (error) {
            console.error('ERROR: ', error);
            return null;
        }
    }

With a simple GoogleSignin.signIn() it'll automatically handles everything.

Now we'll implement the google sign in button component:

// 3b. renderGoogleSigninButton

const renderGoogleSigninButton = () => {

        const buttonTitle = user ? `Signed in as: ${user.displayName}` : 'Continue with Google'

        return (
            <Pressable style={styles.buttonContainer} onPress={() => onGoogleButtonPress().then((value: FirebaseAuthTypes.UserCredential | null) => {
                    // The onGoogleButtonPress will update the setUser state, so no action needed here
                if (value) {
                    console.log('value.additionalInnfo: ', value.additionalUserInfo);
                    console.log('value.user: ', value.user);
                }
            }).catch((error) => {
                if (isErrorWithCode(error)) {
                    switch (error.code) {
                        case statusCodes.SIGN_IN_CANCELLED:
                            // user cancelled the login flow
                            Alert.alert("User cancelled the login flow. Please try again.");
                            break;
                        case statusCodes.IN_PROGRESS:
                            // operation (eg. sign in) already in progress
                            Alert.alert("Sign In already in progress. Please wait.");
                            break;
                        case statusCodes.PLAY_SERVICES_NOT_AVAILABLE:
                            // play services not available or outdated
                            Alert.alert("Play services not available or outdated. Please update your play services.");
                            break;
                        default:
                            // some other error happened
                            Alert.alert("An unknown error occurred. Please try again later.");
                    }
                } else {
                    // an error that's not related to google sign in occurred
                    Alert.alert("An error that's not related to google sign in occurred. Please try again later.");
                }
            })}>
                <Text>{buttonTitle}</Text>
            </Pressable>
        )
    }

The step 4, let's divide it into smaller parts:

• Implement signOut using auth
• implement a renderLogoutView to implement logout.
• Main screen Components that include login and logout buttons

// 4a.Implement `signOut` using `auth`
// src/api/FirebaseAuthUtils.ts
import auth from '@react-native-firebase/auth';

export function userLogout(): Promise<string> {
    return new Promise((resolve, reject) => {
        auth()
            .signOut()
            .then(() => {
                resolve('Logout Successful');
            })
            .catch(error => {
                reject({
                    title: 'Error',
                    desc: error.message,
                });
            });
    });
}

Created a new file in src/api/FirebaseAuthUtils.ts and added a logout function.

Everything below is in Login.tsx

// 4b. Implement a `renderLogoutView` to implement logout.

import { userLogout } from "../api/FirebaseAuthUtils";
//... other imports

    const renderLogoutView = () => {
        if (user) {
            return (
                <Pressable onPress={() => {
                    userLogout().then((message) => {
                        Alert.alert(message);
                    }).catch(error => {
                        Alert.alert(error.title, error.desc);
                    });
                }}>
                    <Text style={styles.buttonTitle}>Logout</Text>
                </Pressable>
            )
        }
    }

// 4c. Main screen `Components` that include login and logout buttons

return (
        <ScrollView>
                {!user && <>
                    <Text style={styles.descriptionText}>
                        New or returning user, press{'\n'}
                        <Text style={styles.boldText}>Continue with Google
                        </Text> to continue
                    </Text>
                    {renderGoogleSigninButton()}
                </>}
                {renderLogoutView()}
        </ScrollView>
)

That's all the code that is needed. Next let's test it.

Testing

I tested on simulator and device, it works.

I am not logged in, so it shows the Login button:

I am logged in, so it shows the Logout button:

It'll take user to Google Sign In page for verification.

Logout test and it works as expected.

Errors

If you're getting this error:

 LOG  ERROR:  [Error: DEVELOPER_ERROR]
 LOG  ERROR:  10 DEVELOPER_ERROR

Add the SHA-1 and SHA-256. If you only have debug build then just add for that otherwise add total 4; 2 for debug and 2 for release:

Below is the command you can run to get all the available SHA fingerprints:

cd android && ./gradlew signingReport

Scroll down to find > Task :app:signingReport. Here you can find all the available SHA fingerprints. I only have debug so for me release and debug keys are the same, so in the above screenshot you see only two SHA fingerprints.

This solves the 10 DEVELOPER_ERROR.

---

If you're getting:

[Error: SIGN_IN_REQUIRED]

Make sure that your signOut is properly configured. Try deleting the app and installing again.