I'm using flutter and managing data by cloud_firestore. I could send data to firestore, but now I'm Struggling with reading data.
In firestore, data are stored like this;
"users" collection -> "(uid)" document -> "userName" string field
And this is the code which I trying. Showing LinerProgressIndicator till snapshot has done.
CollectionReference users = FirebaseFirestore.instance.collection('users');
FutureBuilder(
future: users.doc().get(),
builder: (context, AsyncSnapshot<DocumentSnapshot> snapshot) {
if (snapshot.connectionState != ConnectionState.done) {
return const SizedBox(
width: 50,
child: LinearProgressIndicator(),
);
}
if (snapshot.hasError) {
return SelectableText(snapshot.error.toString());
}
if (!snapshot.hasData) {
return const Text('No data found');
}
Map<String, dynamic> data =
snapshot.data!.data() as Map<String, dynamic>;
return Text("User Name: ${data['userName']}");
},
)
But when snapshot done, error occurred.
Expected a value of type 'Map<String, dynamic>', but got one of type 'Null'
I referenced One-time Read item this official article
I have confirmed that the values for 'users' -> uid -> 'userName' are correct.
Addition 1:
I debugged builder of FutureBuilder.
print('${snapshot.data!.data()}');
null
print('${snapshot.data}');
Instance of '_JsonDocumentSnapshot'
Addition 2:
@Saiful Islam
I rewrote the code. Then other error occurred.
Expected a value of type 'Map<String, dynamic>', but got one of type '_JsonDocumentSnapshot'
Also, print() result is same as Addition 1.
test code;
CollectionReference users = FirebaseFirestore.instance.collection('users');
FutureBuilder(
future: users.doc(FirebaseAuth.instance.currentUser!.uid).get(),
builder: (context, AsyncSnapshot<DocumentSnapshot> snapshot) {
print('${snapshot.data!.data()}'); //null
print('${snapshot.data}'); //Instance of '_JsonDocumentSnapshot'
if (snapshot.connectionState != ConnectionState.done) {
return const SizedBox(
width: 50,
child: LinearProgressIndicator(),
);
}
if (snapshot.hasError) {
return SelectableText(snapshot.error.toString());
}
if (!snapshot.hasData) {
return const Text('No data found');
}
if (snapshot.connectionState == ConnectionState.done) {
Map<String, dynamic> data =
snapshot.data as Map<String, dynamic>;
return Text("User Name: ${data['username']}");
}
return const SelectableText("userName");
},
)
Addition 3:##
Added print('${jsonDecode(snapshot.data)}').
Error appears again.
Bad state: cannot get a field on a DocumentSnapshotPlatform which does not exist
Detail of the error;
Launching lib\main.dart on Chrome in debug mode...
This app is linked to the debug service: ws://127.0.0.1:59027/fBobSNPxOzo%3D/ws
Debug service listening on ws://127.0.0.1:59027/fBobSNPxOzo=/ws
Running with sound null safety
Connecting to VM Service at ws://127.0.0.1:59027/fBobSNPxOzo=/ws
════════ Exception caught by widgets library ═══════════════════════════════════
The following StateError was thrown building FutureBuilder<DocumentSnapshot<Object?>>(dirty, state: _FutureBuilderState<DocumentSnapshot<Object?>>#330c8):
Bad state: cannot get a field on a DocumentSnapshotPlatform which does not exist
The relevant error-causing widget was
FutureBuilder<DocumentSnapshot<Object?>> FutureBuilder:file:///D:/FlutterProjects/testProject/lib/profile.dart:32:13
When the exception was thrown, this was the stack
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/errors.dart 251:49 throw_
packages/cloud_firestore_platform_interface/src/platform_interface/platform_interface_document_snapshot.dart 77:7 get
packages/cloud_firestore/src/document_snapshot.dart 92:48 get
packages/cloud_firestore/src/document_snapshot.dart 96:40 _get
packages/testProject/profile.dart 50:45 <fn>
packages/flutter/src/widgets/async.dart 782:48 build
packages/flutter/src/widgets/framework.dart 4782:27 build
packages/flutter/src/widgets/framework.dart 4665:15 performRebuild
packages/flutter/src/widgets/framework.dart 4840:11 performRebuild
packages/flutter/src/widgets/framework.dart 4355:5 rebuild
packages/flutter/src/widgets/framework.dart 2620:31 buildScope
packages/flutter/src/widgets/binding.dart 882:9 drawFrame
packages/flutter/src/rendering/binding.dart 319:5 [_handlePersistentFrameCallback]
packages/flutter/src/scheduler/binding.dart 1143:15 [_invokeFrameCallback]
packages/flutter/src/scheduler/binding.dart 1080:9 handleDrawFrame
packages/flutter/src/scheduler/binding.dart 996:5 [_handleDrawFrame]
C:/b/s/w/ir/cache/builder/src/out/host_debug/flutter_web_sdk/lib/_engine/engine/platform_dispatcher.dart 1003:13 invoke
C:/b/s/w/ir/cache/builder/src/out/host_debug/flutter_web_sdk/lib/_engine/engine/platform_dispatcher.dart 157:5 invokeOnDrawFrame
C:/b/s/w/ir/cache/builder/src/out/host_debug/flutter_web_sdk/lib/_engine/engine.dart 440:45 <fn>
════════════════════════════════════════════════════════════════════════════════
════════ Exception caught by rendering library ═════════════════════════════════
A RenderFlex overflowed by 99340 pixels on the bottom.
The relevant error-causing widget was
Column Column:file:///D:/FlutterProjects/testProject/lib/profile.dart:26:20
════════════════════════════════════════════════════════════════════════════════
What kind of problem can you think of?
Thank you.