My ListView Widget is not showing any data - flutter

Question

In my code, i have a listview widget, and i gave data to it from firestore using firebase, and tried to display data on screen as text. But nothing happens, i am not getting any error or something. Still my page is blank. So can anyone tell me that is there a mistake in firebase part or listview one. It will be very helpfull.
Here's my code -
import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:flutter/material.dart';
import 'package:social_app/widgets/header.dart';
import 'package:social_app/widgets/progress.dart';
final userRef = FirebaseFirestore.instance.collection("users");
class Timeline extends StatefulWidget {
#override
_TimelineState createState() => _TimelineState();
}
class _TimelineState extends State<Timeline> {
List<dynamic> users = [];
#override
void initState() {
// TODO: implement initState
super.initState();
getUserById();
getUsers();
}
getUserById() {
}
getUsers() async {
final QuerySnapshot snapshot = await userRef.get();
setState(() {
users = snapshot.docs;
});
// snapshot.docs.forEach((DocumentSnapshot doc) {
// print(doc.data());
// print(doc.id);
// print(doc.exists);
// });
}
#override
Widget build(context) {
return SafeArea(
child: Scaffold(
backgroundColor: Colors.black,
appBar: header(context, isAppTitle: true),
body: Container(
child: ListView(
children: users.map((user) => Text(user['username'], style: TextStyle(color: Colors.white),)).toList()
),
),
),
);
}
}
Here's my run output -
Performing hot reload...
Syncing files to device sdk gphone x86...
Reloaded 3 of 800 libraries in 817ms.
W/Firestore( 3283): (21.7.1) [Firestore]: Listen for Query(target=Query(users order by __name__);limitType=LIMIT_TO_FIRST) failed: Status{code=PERMISSION_DENIED, description=Missing or insufficient permissions., cause=null}
E/flutter ( 3283): [ERROR:flutter/lib/ui/ui_dart_state.cc(177)] Unhandled Exception: [cloud_firestore/permission-denied] The caller does not have permission to execute the specified operation.
E/flutter ( 3283): #0 MethodChannelQuery.get (package:cloud_firestore_platform_interface/src/method_channel/method_channel_query.dart:105:7)
E/flutter ( 3283): <asynchronous suspension>
E/flutter ( 3283): #1 Query.get (package:cloud_firestore/src/query.dart:178:25)
E/flutter ( 3283): #2 _TimelineState.getUsers (package:social_app/pages/timeline.dart:29:50)
E/flutter ( 3283): #3 _TimelineState.initState (package:social_app/pages/timeline.dart:22:5)
E/flutter ( 3283): #4 StatefulElement._firstBuild (package:flutter/src/widgets/framework.dart:4765:58)
E/flutter ( 3283): #5 ComponentElement.mount (package:flutter/src/widgets/framework.dart:4601:5)
E/flutter ( 3283): #6 Element.inflateWidget (package:flutter/src/widgets/framework.dart:3569:14)
E/flutter ( 3283): #7 Element.updateChild (package:flutter/src/widgets/framework.dart:3327:18)
E/flutter ( 3283): #8 SingleChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:6118:14)
E/flutter ( 3283): #9 Element.inflateWidget (package:flutter/src/widgets/framework.dart:3569:14)
E/flutter ( 3283): #10 Element.updateChild (package:flutter/src/widgets/framework.dart:3327:18)
E/flutter ( 3283): #11 SingleChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:6118:14)
E/flutter ( 3283): #12 Element.inflateWidget (package:flutter/src/widgets/framework.dart:3569:14)
E/flutter ( 3283): #13 Element.updateChild (package:flutter/src/widgets/framework.dart:3327:18)
E/flutter ( 3283): #14 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:4652:16)
E/flutter ( 3283): #15 Element.rebuild (package:flutter/src/widgets/framework.dart:4343:5)
E/flutter ( 3283): #16 ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:4606:5)
E/flutter ( 3283): #17 ComponentElement.mount (package:flutter/src/widgets/framework.dart:4601:5)
E/flutter ( 3283): #18 Element.inflateWidget (package:flutter/src/widgets/framework.dart:3569:14)
E/flutter ( 3283): #19 Element.updateChild (package:flutter/src/widgets/framework.dart:3327:18)
E/flutter ( 3283): #20 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:4652:16)
E/flutter ( 3283): #21 Element.rebuild (package:flutter/src/widgets/framework.dart:4343:5)
E/flutter ( 3283): #22 ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:4606:5)
E/flutter ( 3283): #23 ComponentElement.mount (package:flutter/src/widgets/framework.dart:4601:5)
E/flutter ( 3283): #24 Element.inflateWidget (package:flutter/src/widgets/framework.dart:3569:14)
E/flutter ( 3283): #25 Element.updateChild (package:flutter/src/widgets/framework.dart:3327:18)
E/flutter ( 3283): #26 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:4652:16)
E/flutter ( 3283): #27 StatefulElement.performRebuild (package:flutter/src/widgets/framework.dart:4800:11)
E/flutter ( 3283): #28 Element.rebuild (package:flutter/src/widgets/framework.dart:4343:5)
E/flutter ( 3283): #29 ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:4606:5)
E/flutter ( 3283): #30 StatefulElement._firstBuild (package:flutter/src/widgets/framework.dart:4791:11)
E/flutter ( 3283): #31 ComponentElement.mount (package:flutter/src/widgets/framework.dart:4601:5)
E/flutter ( 3283): #32 Element.inflateWidget (package:flutter/src/widgets/framework.dart:3569:14)
E/flutter ( 3283): #33 Element.updateChild (package:flutter/src/widgets/framework.dart:3327:18)
E/flutter ( 3283): #34 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:4652:16)
E/flutter ( 3283): #35 Element.rebuild (package:flutter/src/widgets/framework.dart:4343:5)
E/flutter ( 3283): #36 ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:4606:5)
E/flutter ( 3283): #37 ComponentElement.mount (package:flutter/src/widgets/framework.dart:4601:5)
E/flutter ( 3283): #38 Element.inflateWidget (package:flutter/src/widgets/framework.dart:3569:14)
E/flutter ( 3283): #39 Element.updateChild (package:flutter/src/widgets/framework.dart:3327:18)
E/flutter ( 3283): #40 SliverMultiBoxAdaptorElement.updateChild (package:flutter/src/widgets/sliver.dart:1158:36)
E/flutter ( 3283): #41 SliverMultiBoxAdaptorElement.createChild.<anonymous closure> (package:flutter/src/widgets/sliver.dart:1143:20)
E/flutter ( 3283): #42 BuildOwner.buildScope (package:flutter/src/widgets/framework.dart:2683:19)
E/flutter ( 3283): #43 SliverMultiBoxAdaptorElement.createChild (package:flutter/src/widgets/sliver.dart:1136:11)
E/flutter ( 3283): #44 RenderSliverMultiBoxAdaptor._createOrObtainChild.<anonymous closure> (package:flutter/src/rendering/sliver_multi_box_adaptor.dart:350:23)
E/flutter ( 3283): #45 RenderObject.invokeLayoutCallback.<anonymous closure> (package:flutter/src/rendering/object.dart:1883:59)
E/flutter ( 3283): #46 PipelineOwner._enableMutationsToDirtySubtrees (package:flutter/src/rendering/object.dart:915:15)
E/flutter ( 3283): #47 RenderObject.invokeLayoutCallback (package:flutter/src/rendering/object.dart:1883:14)
E/flutter ( 3283): #48 RenderSliverMultiBoxAdaptor._createOrObtainChild (package:flutter/src/rendering/sliver_multi_box_adaptor.dart:339:5)
E/flutter ( 3283): #49 RenderSliverMultiBoxAdaptor.insertAndLayoutLeadingChild (package:flutter/src/rendering/sliver_multi_box_adaptor.dart:455:5)
E/flutter ( 3283): #50 RenderSliverFixedExtentBoxAdaptor.performLayout (package:flutter/src/rendering/sliver_fixed_extent_list.dart:234:32)
E/flutter ( 3283): #51 RenderObject.layout (package:flutter/src/rendering/object.dart:1777:7)
E/flutter ( 3283): #52 RenderSliverEdgeInsetsPadding.performLayout (package:flutter/src/rendering/sliver_padding.dart:132:12)
E/flutter ( 3283): #53 _RenderSliverFractionalPadding.performLayout (package:flutter/src/widgets/sliver_fill.dart:170:11)
E/flutter ( 3283): #54 RenderObject.layout (package:flutter/src/rendering/object.dart:1777:7)
E/flutter ( 3283): #55 RenderViewportBase.layoutChildSequence (package:flutter/src/rendering/viewport.dart:507:13)
E/flutter ( 3283): #56 RenderViewport._attemptLayout (package:flutter/src/rendering/viewport.dart:1561:12)
E/flutter ( 3283): #57 RenderViewport.performLayout (package:flutter/src/rendering/viewport.dart:1470:20)
E/flutter ( 3283): #58 RenderObject._layoutWithoutResize (package:flutter/src/rendering/object.dart:1634:7)
E/flutter ( 3283): #59 PipelineOwner.flushLayout (package:flutter/src/rendering/object.dart:884:18)
E/flutter ( 3283): #60 RendererBinding.drawFrame (package:flutter/src/rendering/binding.dart:436:19)
E/flutter ( 3283): #61 WidgetsBinding.drawFrame (package:flutter/src/widgets/binding.dart:914:13)
E/flutter ( 3283): #62 RendererBinding._handlePersistentFrameCallback (package:flutter/src/rendering/binding.dart:302:5)
E/flutter ( 3283): #63 SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:1117:15)
E/flutter ( 3283): #64 SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:1055:9)
E/flutter ( 3283): #65 SchedulerBinding._handleDrawFrame (package:flutter/src/scheduler/binding.dart:971:5)
E/flutter ( 3283): #66 _rootRun (dart:async/zone.dart:1190:13)
E/flutter ( 3283): #67 _CustomZone.run (dart:async/zone.dart:1093:19)
E/flutter ( 3283): #68 _CustomZone.runGuarded (dart:async/zone.dart:997:7)
E/flutter ( 3283): #69 _invoke (dart:ui/hooks.dart:251:10)
E/flutter ( 3283): #70 _drawFrame (dart:ui/hooks.dart:209:3)
E/flutter ( 3283):
W/Firestore( 3283): (21.7.1) [WatchStream]: (a99c49e) Stream closed with status: Status{code=CANCELLED, description=Disconnecting idle stream. Timed out waiting for new targets., cause=null}.
W/ansh.social_ap( 3283): Accessing hidden method Ldalvik/system/CloseGuard;->close()V (greylist,core-platform-api, linking, allowed)

Answer 1

Your code seems to be working fine. Let me explain your problem.
When you create your cloud_firestore for the first time, then permission for accessing the data is set to public in the rules tab. This permission is public for 30 days. After that firestore turned it off and you have to define your own rule.
Here, rules are the actual permission which decide who can access your data and who cannot. Hence, for the time being you can again make the data public by changing the Rules.
Access the Rule tab by following the image below:
Change the Rules at firestore console accordingly. Here is the link to rules documentation.
Note:
You can make the Rules public for testing purposes but don't make it public permanently it will make your data insecure.