从 Uid 获取用户电子邮件，无需登录应用 Firebase

Question

I have created a Firebase app.

Is there any way to get user email by Uid Without login to the app?

Answer 1

No the user has to be logged in to be able to retrieve his information based on the userid

To get the uid, you need to do this:

FirebaseUser user=FirebaseAuth.getInstance().getCurrentUser();
String userid=user.getUid();

According to the docs:

public FirebaseUser getCurrentUser ()

Returns the currently signed-in FirebaseUser or null if there is none.

more info here:

https://firebase.google.com/docs/reference/android/com/google/firebase/auth/FirebaseAuth.html#getCurrentUser()

Answer 2

Of course it is possible, you can use Firebase Cloud Functions . You can write a cloud function which will return user mail by UID param :) No firebase authentication required, simple and awesome. Here is a short example:

const admin = require('firebase-admin');
exports.getUserMail = functions.https.onRequest((req, resp) => {
    admin.auth().getUser(req.query.uid)
}

Answer 3

It is not possible without logging in. Your email address and password are stored separately from the user data for security reasons. See below:

How do I return a list of users if I use the Firebase simple username & password authentication

Answer 4

Use the Firebase Admin SDK. You can lookup a user by uid, email or phone number: https://firebase.google.com/docs/auth/admin/manage-users#retrieve_user_data

admin.auth().getUser(uid)
  .then(function(userRecord) {
    console.log(userRecord.email);
  })
  .catch(function(error) {
    console.log("Error fetching user data:", error);
  });