'firebase/main.dart': Failed assertion - firebase

Question

I have made a simple baby names project using firebase on flutter,
after successfully going throught the tutorial, the app gives this error : " package:firebase_demo/main.dart': Failed assertion: line 86 pos 16: 'map['votes] ! = null': is not true. "
Help for the same.
MY CODE -:
import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:flutter/material.dart';
void main() => runApp(MyApp());
final dummySnapshot = [
{"name": "Filip", "votes": 15},
{"name": "Abraham", "votes": 14},
{"name": "Richard", "votes": 11},
{"name": "Ike", "votes": 10},
{"name": "Justin", "votes": 1},
];
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Baby Names',
home: MyHomePage(),
);
}
}
class MyHomePage extends StatefulWidget {
#override
_MyHomePageState createState() {
return _MyHomePageState();
}
}
class _MyHomePageState extends State<MyHomePage> {
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(title: Text('Baby Name Votes')),
body: _buildBody(context),
);
}
Widget _buildBody(BuildContext context) {
return StreamBuilder<QuerySnapshot>(
stream: Firestore.instance.collection('baby').snapshots(),
builder: (context, snapshot) {
if (!snapshot.hasData) return LinearProgressIndicator();
return _buildList(context, snapshot.data.documents);
},
);
}
Widget _buildList(BuildContext context, List<DocumentSnapshot> snapshot) {
return ListView(
padding: const EdgeInsets.only(top: 20.0),
children: snapshot.map((data) => _buildListItem(context, data)).toList(),
);
}
Widget _buildListItem(BuildContext context, DocumentSnapshot data) {
final record = Record.fromSnapshot(data);
return Padding(
key: ValueKey(record.name),
padding: const EdgeInsets.symmetric(horizontal: 16.0, vertical: 8.0),
child: Container(
decoration: BoxDecoration(
border: Border.all(color: Colors.grey),
borderRadius: BorderRadius.circular(5.0),
),
child: ListTile(
title: Text(record.name),
trailing: Text(record.votes.toString()),
onTap: () => print(record),
),
),
);
}
}
class Record {
final String name;
final int votes;
final DocumentReference reference;
Record.fromMap(Map<String, dynamic> map, {this.reference})
: assert(map['name'] != null),
assert(map['votes'] != null),
name = map['name'],
votes = map['votes'];
Record.fromSnapshot(DocumentSnapshot snapshot)
: this.fromMap(snapshot.data, reference: snapshot.reference);
#override
String toString() => "Record<$name:$votes>";
}
Output :
Performing hot restart...
Syncing files to device Redmi Note 4...
Restarted application in 1,994ms.
I/flutter ( 2257): ══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════
I/flutter ( 2257): The following assertion was thrown building StreamBuilder(dirty, state:
I/flutter ( 2257): _StreamBuilderBaseState>#94c3a):
I/flutter ( 2257): 'package:firebase_demo/main.dart': Failed assertion: line 86 pos 16: 'map['votes'] != null': is not
I/flutter ( 2257): true.
I/flutter ( 2257):
I/flutter ( 2257): Either the assertion indicates an error in the framework itself, or we should provide substantially
I/flutter ( 2257): more information in this error message to help you determine and fix the underlying cause.
I/flutter ( 2257): In either case, please report this assertion by filing a bug on GitHub:
I/flutter ( 2257): https://github.com/flutter/flutter/issues/new?template=BUG.md
I/flutter ( 2257):
I/flutter ( 2257): When the exception was thrown, this was the stack:
I/flutter ( 2257): #2 new Record.fromMap (package:firebase_demo/main.dart:86:16)
I/flutter ( 2257): #3 new Record.fromSnapshot (package:firebase_demo/main.dart:91:14)
I/flutter ( 2257): #4 _MyHomePageState._buildListItem (package:firebase_demo/main.dart:59:27)
I/flutter ( 2257): #5 _MyHomePageState._buildList. (package:firebase_demo/main.dart:54:40)
I/flutter ( 2257): #6 MappedListIterable.elementAt (dart:_internal/iterable.dart:414:29)
I/flutter ( 2257): #7 ListIterable.toList (dart:_internal/iterable.dart:219:19)
I/flutter ( 2257): #8 _MyHomePageState._buildList (package:firebase_demo/main.dart:54:71)
I/flutter ( 2257): #9 _MyHomePageState._buildBody. (package:firebase_demo/main.dart:46:16)
I/flutter ( 2257): #10 StreamBuilder.build (package:flutter/src/widgets/async.dart:423:74)
I/flutter ( 2257): #11 _StreamBuilderBaseState.build (package:flutter/src/widgets/async.dart:125:48)
I/flutter ( 2257): #12 StatefulElement.build (package:flutter/src/widgets/framework.dart:3809:27)
I/flutter ( 2257): #13 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3721:15)
I/flutter ( 2257): #14 Element.rebuild (package:flutter/src/widgets/framework.dart:3547:5)
I/flutter ( 2257): #15 BuildOwner.buildScope (package:flutter/src/widgets/framework.dart:2286:33)
I/flutter ( 2257): #16 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding&PaintingBinding&SemanticsBinding&RendererBinding&WidgetsBinding.drawFrame (package:flutter/src/widgets/binding.dart:676:20)
I/flutter ( 2257): #17 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding&PaintingBinding&SemanticsBinding&RendererBinding._handlePersistentFrameCallback (package:flutter/src/rendering/binding.dart:219:5)
I/flutter ( 2257): #18 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:990:15)
I/flutter ( 2257): #19 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:930:9)
I/flutter ( 2257): #20 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding._handleDrawFrame (package:flutter/src/scheduler/binding.dart:842:5)
I/flutter ( 2257): #21 _invoke (dart:ui/hooks.dart:154:13)
I/flutter ( 2257): #22 _drawFrame (dart:ui/hooks.dart:143:3)
I/flutter ( 2257): (elided 2 frames from class _AssertionError)
I/flutter ( 2257): ════════════════════════════════════════════════════════════════════════════════════════════════════
I/1.gpu ( 2257): type=1400 audit(0.0:191179): avc: denied { ioctl } for path="/dev/kgsl-3d0" dev="tmpfs" ino=15394 ioctlcmd=945 scontext=u:r:untrusted_app_27:s0:c512,c768 tcontext=u:object_r:device:s0 tclass=chr_file permissive=1
I/1.gpu ( 2257): type=1400 audit(0.0:191180): avc: denied { read write } for path="/dev/kgsl-3d0" dev="tmpfs" ino=15394 scontext=u:r:untrusted_app_27:s0:c512,c768 tcontext=u:object_r:device:s0 tclass=chr_file permissive=1
I/an.firebasedem( 2257): Waiting for a blocking GC ProfileSaver
I/an.firebasedem( 2257): WaitForGcToComplete blocked ProfileSaver on ProfileSaver for 30.771ms

Answer 1

Maybe you can check your collection name in the firebase first.
stream: Firestore.instance.collection('your_collection_name_here').snapshots(),

Answer 2

Make sure your fields in the Firebase match with the proprieties of Record.
e.g:
name matches name field from the database
votes matches votes field from the database