Not able to fetch particular user document by user id in flutter app

user_11801135 0
Viewed 1265

I want to retrieve a particular user document by its id from the collection users. When I directly pass the particular user id, I get the data. But when I pass it using variable it shows null.

My code is as follows:

import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:flutter/material.dart';
import 'package:firebase_auth/firebase_auth.dart';
import '../services/crud.dart';

class test extends StatefulWidget {
  @override
  _testState createState() => _testState();

}
class _testState extends State<test> {

  String userID="";
  @override
  void initState() {
    super.initState();
    ///get current user and assign his id
    FirebaseAuth.instance.currentUser().then((FirebaseUser user) {
      setState(() {
        userID = user.uid;
        print(userID);
      });
    });
  }
  @override
  Widget build(BuildContext context) {
    return SingleChildScrollView(
      child: Column(
        children: <Widget>[
          StreamBuilder(
                  stream: Firestore.instance.collection('users').document(userID).snapshots(),
                  builder: (context,snapshot){
                    if (!snapshot.hasData) return const Text("Loading...");
                    else return Container(
                      child: Column(
                        children: <Widget>[
                          Text(snapshot.data["name"]),
                          Text(snapshot.data["email"]),
                          Text(snapshot.data["phone"].toString()),
                        ],
                      ),
                    );
                  },
                )
        ],
      )
    );
  }
}

When I'm using the following line of code with specifying uid it shows the result :

stream: Firestore.instance.collection('users').document('d6DshRomJMkIe9mAARAi').snapshots(),

But it does not work when I pass userID inside the document(). Even though userID contains the actual id of the logged-in user.

stream: Firestore.instance.collection('users').document(userID).snapshots(),

The error says :

NoSuchMethodError: The method '[]' was called on null.
Receiver: null
Tried calling []("name")

This is the structure of my database.

This is the error that I get on my app screen.

google-cloud-firestore firebase-authentication firebase dart flutter
1 Answers

When using userID is doesn't work because currentUser() is asynchronous and the StreamBuilder is being called even before getting the userId therefore try the following:

   Stream<DocumentSnapshot> getData()async*{
     FirebaseUser user = await FirebaseAuth.instance.currentUser();
     yield* Firestore.instance.collection('users').document(user.uid).snapshots();
  }

Create a method that returns a Stream and then inside the StreamBuilder do the following:

children: <Widget>[
          StreamBuilder(
                  stream: getData(),
                  builder: (context,snapshot){
                    if (!snapshot.hasData) return const Text("Loading...");
                    else if(snapshot.hasData){
                    return Container(
                      child: Column(
                        children: <Widget>[
                          Text(snapshot.data["name"]),
                          Text(snapshot.data["email"]),
                          Text(snapshot.data["phone"].toString()),
                        ],
                      ),
                    );
                   },
                return CircularProgressIndicator();
                  },
                )
        ],
user_70154000
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