Flutter - Getting data with firebase. I show two ways to get dat in the initState, 1. get data once and 2. and get updates in a stream.

main.dart

import 'dart:async';

import 'package:firebase_database/firebase_database.dart';
import 'package:flutter/material.dart';
import 'package:shared_preferences/shared_preferences.dart';

void main() {
  runApp(new MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      title: 'Flutter Demo',
      theme: new ThemeData(
        primarySwatch: Colors.green,
      ),
      home: new HomePage(),
    );
  }
}

class HomePage extends StatefulWidget {
  @override
  _HomePageState createState() => new _HomePageState();
}

class _HomePageState extends State<HomePage> {
  StreamSubscription _subscriptionTodo;

  String _todoName = "Display the todo name here";

  @override
  void initState() {
    //FirebaseTodos.getTodo("-KriJ8Sg4lWIoNswKWc4").then(_updateTodo);

    FirebaseTodos.getTodoStream("-KriJ8Sg4lWIoNswKWc4", _updateTodo)
        .then((StreamSubscription s) => _subscriptionTodo = s);
    super.initState();
  }

  @override
  void dispose() {
    if (_subscriptionTodo != null) {
      _subscriptionTodo.cancel();
    }
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    var itemTile = new ListTile(
      title: new Text("$_todoName"),
    );

    return new Scaffold(
      appBar: new AppBar(
        title: new Text("App Bar Title"),
      ),
      body: new ListView(
        children: <Widget>[
          itemTile,
        ],
      ),
    );
  }


  _updateTodo(Todo value) {
    var name = value.name;
    setState((){
      _todoName = name;
    });
  }
}





class Todo {
  final String key;
  String name;

  Todo.fromJson(this.key, Map data) {
    name = data['name'];
    if (name == null) {
      name = '';
    }
  }
}





class FirebaseTodos {
  /// FirebaseTodos.getTodoStream("-KriJ8Sg4lWIoNswKWc4", _updateTodo)
  /// .then((StreamSubscription s) => _subscriptionTodo = s);
  static Future<StreamSubscription<Event>> getTodoStream(String todoKey,
      void onData(Todo todo)) async {
    String accountKey = await Preferences.getAccountKey();

    StreamSubscription<Event> subscription = FirebaseDatabase.instance
        .reference()
        .child("accounts")
        .child(accountKey)
        .child("todos")
        .child(todoKey)
        .onValue
        .listen((Event event) {
      var todo = new Todo.fromJson(event.snapshot.key, event.snapshot.value);
      onData(todo);
    });

    return subscription;
  }

  /// FirebaseTodos.getTodo("-KriJ8Sg4lWIoNswKWc4").then(_updateTodo);
  static Future<Todo> getTodo(String todoKey) async {
    Completer<Todo> completer = new Completer<Todo>();

    String accountKey = await Preferences.getAccountKey();

    FirebaseDatabase.instance
        .reference()
        .child("accounts")
        .child(accountKey)
        .child("todos")
        .child(todoKey)
        .once()
        .then((DataSnapshot snapshot) {
      var todo = new Todo.fromJson(snapshot.key, snapshot.value);
      completer.complete(todo);
    });

    return completer.future;
  }
}






class Preferences {
  static const String ACCOUNT_KEY = "accountKey";

  static Future<bool> setAccountKey(String accountKey) async {
    SharedPreferences prefs = await SharedPreferences.getInstance();
    prefs.setString(ACCOUNT_KEY, accountKey);
    return prefs.commit();
  }

  static Future<String> getAccountKey() async {
    SharedPreferences prefs = await SharedPreferences.getInstance();
    String accountKey = prefs.getString(ACCOUNT_KEY);

    // workaround - simulate a login setting this
    if (accountKey == null) {
      accountKey = "-KriFiUADpl-X07hnBC-";
    }

    return accountKey;
  }
}

Does this work with firestore?

return ListTile(title: Text(snapshot.value['name']));
Error:- The method '[]' can't be unconditionally invoked because the receiver can be 'null'.
Try making the call conditional (using '?.') or adding a null check to the target ('!').

plz solve this

return ListTile(title: Text(snapshot.value['name'])); Error:- The method '[]' can't be unconditionally invoked because the receiver can be 'null'. Try making the call conditional (using '?.') or adding a null check to the target ('!').

plz solve this

Add null check
ex: Text(snapshot.value['name'] ?? " " ),

send me the address of anydesk

…

On Sun, 11 Dec 2022 at 21:15, Aditya More ***@***.***> wrote: ***@***.**** commented on this gist. ------------------------------ return ListTile(title: Text(snapshot.value['name'])); Error:- The method '[]' can't be unconditionally invoked because the receiver can be 'null'. Try making the call conditional (using '?.') or adding a null check to the target ('!'). plz solve this Add null check ex: Text(snapshot.value['name']??"", — Reply to this email directly, view it on GitHub <https://gist.github.com/ea80ce71179c41fdd8bbdb796ca889f4#gistcomment-4398964> or unsubscribe <https://github.com/notifications/unsubscribe-auth/AYGLZGUUUJLGF6FC53IFO2LWMXZIBBFKMF2HI4TJMJ2XIZLTSKBKK5TBNR2WLJDHNFZXJJDOMFWWLK3UNBZGKYLEL52HS4DFQKSXMYLMOVS2I5DSOVS2I3TBNVS3W5DIOJSWCZC7OBQXE5DJMNUXAYLOORPWCY3UNF3GS5DZVRZXKYTKMVRXIX3UPFYGLK2HNFZXIQ3PNVWWK3TUUZ2G64DJMNZZDAVEOR4XAZNEM5UXG5FFOZQWY5LFVA4DQMBUGQYTMOFHORZGSZ3HMVZKMY3SMVQXIZI> . You are receiving this email because you commented on the thread. Triage notifications on the go with GitHub Mobile for iOS <https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675> or Android <https://play.google.com/store/apps/details?id=com.github.android&referrer=utm_campaign%3Dnotification-email%26utm_medium%3Demail%26utm_source%3Dgithub> .