react native firebase authentication users id

Question

I made an authentication using firebase and firestore. When the user registers, I create a collection called users in firestore and save the user's information in the document. My goal is to reach the document id in the users collection of the registered user. my codes:

let createUser = async (email, password, firstName, lastName) => {
    await firebase.auth().createUserWithEmailAndPassword(email, password)
        .then(() => {
            firebase.auth().currentUser.sendEmailVerification({
                handleCodeInApp: true,
                url: "https://hpom-ca649.firebaseapp.com",
            }).then(() => { alert({ alertVerification })
                }).catch((error) => { alert(error.message) })
                .then(() => {
                     addDoc(collection(db,'users'), {
                          first: {firstName},
                          last: {lastName},
                          email: {email}
                        })
                }).catch((error) => { alert(error.message);console.log(error.message) })
        })
}

Answer 1

If you want to be able to easily reach the user's document based on that user's ID, its best to store that document with the UID of the user as its document ID. You can do that by calling setDocument on a DocumentReference instead of addDocument on the CollectionReference .

In code:

firebase.auth().createUserWithEmailAndPassword(email, password)
    .then((credentials) => {
        setDoc(doc(db,'users', credentials.user.uid), {
          first: {firstName},
          last: {lastName},
          email: {email}
        })
    })