How to get documents from Firestore from a list?

Question

Android

There is a list of friends (user-id, maybe several hundred) and there are documents with user data.
Question: how to get the data of the desired users using one query (using this selection)?
For example user1 has friends List['user4', 'user2', 'user19', ..n].
How to get these friends' documents for further display (preferably in a Stream)?

Answer 1

try to make a list in the document, to which the id-document of the desired user will be added, and then you will simply call it.

import 'package:cloud_firestore/cloud_firestore.dart';

class users{

  var userId = 'это id-документа нашего юзера, который выполняет действие';

  //здесь мы берем из его документа список id-документов его друзей
  //который как я понимаю тоже постепенно наполнятеся
  var pathUsers = FirebaseFirestore.instance
      .collection('users').doc(userId).get().then((value) => value.data()['arrayOfPath']);

  
  //здесь можем обращаться к данным каждого юзера-друга
  var getNeedUserData = FirebaseFirestore.instance
      .collection('users').doc(PATHS[index]);


}

I'm certainly not sure what will work, tk. I am a beginner myself, so if you can write)))