Fetch multiple users

Question

I have a list (uid's) of users that is connected to a group. On one page I want to list all usernames and emails of the users in the list.

What is the recommended way to fetch user data for each user? All I can find is in the admin sdk: admin.auth().getUser(uid)

1. Is there no way to fetch multiple users in one request? ex admin.auth().getUsers([uid1, uid2, uid3])?
2. Is there no way to do this in the client sdk?
3. If 1. is not possible, is it not quite easy to reach the limits? https://firebase.google.com/docs/auth/limits#api_limits

Answer 1

It's not possible to retrieve the list of all users with the client SDK, but you can do it in two ways:

Using the Firebase Realtime Database

1. You can add a node of user names and emails, say /users in your database:

   {
     "users": {
       "user1": {
         "username": "user1",
         "email": "user1@mail.com"
       },
       "user2": {
         "username": "user2",
         "email": "user2@mail.com"
       }
     }
   }
   

2. Then just query this node using once('value'):

   const users = await firebase.database.ref('/userProfiles').once('value');
   console.log(users);
   

Using a callable function and the Firebase Admin SDK

1. Create an HTTPS callable function, say getAllUsers(), that retrieves all users. The Firebase Admin SDK has a way to list all users in batches of 1000.

2. Deploy the function using firebase deploy --only functions:getAllUsers.

3. Then call the function from the client:

   const getAllUsers = firebase.functions().httpsCallable('getAllUsers');
   const users = await getAllUsers();
   console.log(users);