I have implemented Apple Sign In to my React Native App using Firebase and the Sign In process is working fine.

I am adding the User details to a Database Collection named 'users' in Firestore.

When the user re-signs in the data which is added to the collection from their Profile gets overwritten.

How can I check if user exists so the collection document is only created once?

My code is as follows

appleSignIn: async () => {
  try {
    const appleAuthRequestResponse = await appleAuth.performRequest({
      requestedOperation: appleAuth.Operation.LOGIN,
      requestedScopes: [appleAuth.Scope.EMAIL, appleAuth.Scope.FULL_NAME],
    });

    if(!appleAuthRequestResponse.identityToken) {
      throw 'Apple Sign-In failed - no identify token returned';
    }
    const { identityToken, nonce } = appleAuthRequestResponse;
    const appleCredential = auth.AppleAuthProvider.credential(identityToken, nonce);
    await auth().signInWithCredential(appleCredential);

    firestore().collection('users').doc(auth().currentUser.uid)
               .set({
                 fname: appleAuthRequestResponse.fullName.givenName,
                 lname: appleAuthRequestResponse.fullName.familyName,
                 email: appleAuthRequestResponse.email,
                 createdAt: firestore.Timestamp.fromDate(new Date()),
                 userImg: null,
               })

  } catch (e) {
    console.log(e);
  }
},

CodePudding user response：

You can check if is user exist in users collection.

...
await auth().signInWithCredential(appleCredential);
const existingUserDoc = await firestore().collection('users').doc(auth().currentUser.uid).get();

if (existingUserDoc && existingUserDoc.exists) {
 // you can do something here. user details already created.
} else {
firestore().collection('users').doc(auth().currentUser.uid)
    .set({
        fname: appleAuthRequestResponse.fullName.givenName,
        lname: appleAuthRequestResponse.fullName.familyName,
        email: appleAuthRequestResponse.email,
        createdAt: firestore.Timestamp.fromDate(new Date()),
        userImg: null,
    });
}
...

Or more simply way if user document exists you can pass firestore().collection('users').doc('uid').set({...}) execution.

...
await auth().signInWithCredential(appleCredential);
const existingUserDoc = await firestore().collection('users').doc(auth().currentUser.uid).get();

// ignore execution of setting user deatils.
if (!existingUserDoc && !existingUserDoc.exists) {
    firestore().collection('users').doc(auth().currentUser.uid)
        .set({
            fname: appleAuthRequestResponse.fullName.givenName,
            lname: appleAuthRequestResponse.fullName.familyName,
            email: appleAuthRequestResponse.email,
            createdAt: firestore.Timestamp.fromDate(new Date()),
            userImg: null,
        });
}
...