Firebase 身份验证：通过 Email 查找用户

Question

I am using Firebase Authentication with Email and Password

I would like to know if i can 'lookup' a user by email only while also not being signed in as a user

The reason I'd like to do this is, is to simply identify if I am already a user of the system, using an email address only

I looked at this older thread but it appears to be the previous version of Firebase

Is it possible to do this in the current Firebase, or my alternative would be to keep this information available (and open to all?) to find out if a given email is part of my system?

Answer 1

I use fetchProvidersForEmail(email) and if the result return as empty array then, this email hasn't been use to sign up.

 firebase.auth().fetchProvidersForEmail(email) .then(providers => { if (providers.length === 0) { // this email hasn't signed up yet } else { // has signed up } });

Answer 2

The new method of creating users with email password returns a value whether the given email address is already in use. See here

Answer 3

You can look up user information by email:

firebase.auth().getUserByEmail(email)
  .then(function(userRecord) {
    // See the UserRecord reference doc for the contents of userRecord.
    console.log('Successfully fetched user data:', userRecord.toJSON());
  })
  .catch(function(error) {
   console.log('Error fetching user data:', error);
  });

Retrieve user data

Answer 4

Server side option:

https://cloud.google.com/identity-platform/docs/reference/rest/v1/projects.accounts/lookup

POST https://identitytoolkit.googleapis.com/v1/projects/{targetProjectId}/accounts:lookup

{ "email": ["rodneydangerfield@stackoverflow.kom"] }

Answer 5

import { fetchSignInMethodsForEmail } from 'firebase/auth'

fetchSignInMethodsForEmail(auth, registerEamil).then((result) =>{
        console.log("result", result);
        if (result.length === 0) {
            Navigate("/authentication/select_role/" + 
      registerEamil)
        } else {
            Navigate('/')
        }
  

Answer 6

As for today 2021 Nov. 18th, there is no way provided by the Firebase SDK to fetch a user by email.