我有兩個系列::
- 團體
- 組用戶
組用戶集合有檔案...每個檔案有兩個欄位
- 組號
- 用戶身份
組集合有檔案...每個檔案有兩個欄位
- 群組管理員 ID
- 團隊名字
使用當前登錄的用戶，我想做以下事情：
查詢組用戶集合以獲取組 ID，
查詢組集合以獲取組名稱。
我覺得很簡單……但我做不到
這是我正在使用的功能：
printData() {
var arr = [];
groupUser.snapshots().listen((data) {
data.docs.forEach((element) {
print(element['Group id']);
arr.add(element['Group id']);
});
});
return arr.first;
}
我收到以下錯誤，但列印陳述句有效：
The following StateError was thrown building TestView(dirty, state: _TestViewState#38814):
Bad state: No element
The relevant error-causing widget was
TestView
lib/views_and_widgets/navigator_view.dart:36
When the exception was thrown, this was the stack
#0 List.first (dart:core-patch/growable_array.dart:343:5)
#1 FirebaseCloudStorage.printData
package:ijob_clone_app/…/cloud/firebase_cloud_storage.dart:87
#2 _TestViewState.build
package:ijob_clone_app/views_and_widgets/test_view.dart:35
#3 StatefulElement.build
package:flutter/…/widgets/framework.dart:4992
#4 ComponentElement.performRebuild
package:flutter/…/widgets/framework.dart:4878
#5 StatefulElement.performRebuild
package:flutter/…/widgets/framework.dart:5050
#6 Element.rebuild
package:flutter/…/widgets/framework.dart:4604
#7 ComponentElement._firstBuild
package:flutter/…/widgets/framework.dart:4859
#8 StatefulElement._firstBuild
package:flutter/…/widgets/framework.dart:5041
#9 ComponentElement.mount
package:flutter/…/widgets/framework.dart:4853
... Normal element mounting (25 frames)
#34 Element.inflateWidget
package:flutter/…/widgets/framework.dart:3863
#35 MultiChildRenderObjectElement.inflateWidget
package:flutter/…/widgets/framework.dart:6435
#36 MultiChildRenderObjectElement.mount
package:flutter/…/widgets/framework.dart:6447
... Normal element mounting (113 frames)
#149 Element.inflateWidget
package:flutter/…/widgets/framework.dart:3863
#150 Element.updateChild
package:flutter/…/widgets/framework.dart:3586
#151 ComponentElement.performRebuild
package:flutter/…/widgets/framework.dart:4904
#152 StatefulElement.performRebuild
package:flutter/…/widgets/framework.dart:5050
#153 Element.rebuild
package:flutter/…/widgets/framework.dart:4604
#154 BuildOwner.buildScope
package:flutter/…/widgets/framework.dart:2667
#155 WidgetsBinding.drawFrame
package:flutter/…/widgets/binding.dart:882
#156 RendererBinding._handlePersistentFrameCallback
package:flutter/…/rendering/binding.dart:378
#157 SchedulerBinding._invokeFrameCallback
package:flutter/…/scheduler/binding.dart:1175
#158 SchedulerBinding.handleDrawFrame
package:flutter/…/scheduler/binding.dart:1104
#159 SchedulerBinding._handleDrawFrame
package:flutter/…/scheduler/binding.dart:1015
#160 _invoke (dart:ui/hooks.dart:148:13)
#161 PlatformDispatcher._drawFrame (dart:ui/platform_dispatcher.dart:318:5)
這是我要列印的螢屏：
class TestView extends StatefulWidget {
const TestView({Key? key}) : super(key: key);
@override
_TestViewState createState() => _TestViewState();
}
class _TestViewState extends State<TestView> {
late final FirebaseCloudStorage _groupUsersService;
String get userId => AuthService.firebase().currentUser!.id; // this is how I get the current logged in users userId
@override
void initState() {
_groupUsersService = FirebaseCloudStorage();
super.initState();
}
@override
Widget build(BuildContext context) {
print(_groupUsersService.printData()); // THIS IS THE PRINT STATEMENT
return Scaffold(
appBar: AppBar(
title: const Text('All users in my group'),
// ignore: prefer_const_literals_to_create_immutables
actions: [
// ignore: prefer_const_constructors
IconButton(
onPressed: null,
icon: const Icon(Icons.add),
),
],
),
body: StreamBuilder(
stream: _groupUsersService.getAllUsersInMyGroup(userId: userId),
builder: (context, snapshot) {
switch (snapshot.connectionState) {
case ConnectionState.waiting:
case ConnectionState.active:
if (snapshot.hasData) {
final allUsers = snapshot.data as Iterable<CloudGroupUser>;
return GroupUserListView(
cloudUsers: allUsers,
// onDeleteJob: (job) async {
// await _groupUsersService.deleteJob(documentId: job.documentId);
// },
onTap: (job) {
Navigator.of(context).pushNamed(
newJobRoute,
arguments: job,
);
},
);
} else {
return const CircularProgressIndicator();
}
default:
return const CircularProgressIndicator();
}
},
),
);
}
}
我從以下資訊的視圖中洗掉了列印宣告（它仍然不起作用）
我什至試圖讓它異步::
printData() async {
var arr = [];
await groupUser.snapshots().listen((data) {
data.docs.forEach((element) {
//print(element['Group id']);
arr.add(element['Group id']);
});
});
print(arr.first);
}
Restarted application in 525ms.
D/EGL_emulation( 4267): app_time_stats: avg=763.88ms min=17.12ms max=2249.43ms count=3
E/flutter ( 4267): [ERROR:flutter/runtime/dart_vm_initializer.cc(41)] Unhandled Exception: Bad state: No element
E/flutter ( 4267): #0 List.first (dart:core-patch/growable_array.dart:343:5)
E/flutter ( 4267): #1 FirebaseCloudStorage.printData
package:ijob_clone_app/…/cloud/firebase_cloud_storage.dart:88
E/flutter ( 4267): <asynchronous suspension>
E/flutter ( 4267):
W/DynamiteModule( 4267): Local module descriptor class for com.google.android.gms.providerinstaller.dynamite not found.
I/DynamiteModule( 4267): Considering local module com.google.android.gms.providerinstaller.dynamite:0 and remote module com.google.android.gms.providerinstaller.dynamite:0
W/ProviderInstaller( 4267): Failed to load providerinstaller module: No acceptable module com.google.android.gms.providerinstaller.dynamite found. Local version is 0 and remote version is 0.
D/TrafficStats( 4267): tagSocket(141) with statsTag=0xffffffff, statsUid=-1
=============== =======================
我也嘗試了以下方法并收到此錯誤
printData() async {
var arr = [];
await groupUser.snapshots().listen((data) {
data.docs.forEach((element) {
//print(element['Group id']);
arr.add(element.data()['Group id']);
});
});
print(arr.first);
}
視圖上的代碼已更改為以下內容：
@override
Widget build(BuildContext context) {
_groupUsersService.printData();
這是我得到的錯誤
Restarted application in 558ms.
D/EGL_emulation( 4267): app_time_stats: avg=600.59ms min=20.48ms max=1754.64ms count=3
E/flutter ( 4267): [ERROR:flutter/runtime/dart_vm_initializer.cc(41)] Unhandled Exception: Bad state: No element
E/flutter ( 4267): #0 List.first (dart:core-patch/growable_array.dart:343:5)
E/flutter ( 4267): #1 FirebaseCloudStorage.printData
package:ijob_clone_app/…/cloud/firebase_cloud_storage.dart:98
E/flutter ( 4267): <asynchronous suspension>
E/flutter ( 4267):
W/DynamiteModule( 4267): Local module descriptor class for com.google.android.gms.providerinstaller.dynamite not found.
I/DynamiteModule( 4267): Considering local module com.google.android.gms.providerinstaller.dynamite:0 and remote module com.google.android.gms.providerinstaller.dynamite:0
W/ProviderInstaller( 4267): Failed to load providerinstaller module: No acceptable module com.google.android.gms.providerinstaller.dynamite found. Local version is 0 and remote version is 0.
D/TrafficStats( 4267): tagSocket(123) with statsTag=0xffffffff, statsUid=-1
W/System ( 4267): Ignoring header X-Firebase-Locale because its value was null.
D/TrafficStats( 4267): tagSocket(121) with statsTag=0xffffffff, statsUid=-1
D/FirebaseAuth( 4267): Notifying id token listeners about user ( U8EZAjrCWQRvll6CVmI6OpGZwcH3 ).
uj5u.com熱心網友回復：
您應該使用element.data()['Group id']而不是element['Group id'].
快樂編碼:)
uj5u.com熱心網友回復：
.onSnapshot()是一個異步觀察者。它回傳一個帶有連接的通用物件。首先檢查他要求退出的資料，然后將其分配到某處或不使用快照，使用簡單的.get()方法。不幸的是，我無法為您提供更多幫助，因為我不是 swift/flutter 程式員。
uj5u.com熱心網友回復：
我一直在尋找這樣的東西
Future getAllUsersInManagersGroup(String userId) async {
//* managersGroupId: group id to which manager belongs to
//* allGroupUsersDocs: all GroupUser docs
//* allUserGroups: all GroupUsers in a List form
//* usersInManagersGroup: all users in managers group
// assumption: manager can only be in one group
String? managersGroupId;
final allGroupUsersDocs = await groupUser.get();
final allUserGroups = allGroupUsersDocs.docs.map((e) => e.data()).toList();
for (var user in allUserGroups) {
if (user['User id'] == userId) {
managersGroupId = user['Group id'];
break;
}
}
if (managersGroupId == null) return null;
var usersInManagersGroup = [];
for (var user in allUserGroups) {
if (user['Group id'] == managersGroupId) {
usersInManagersGroup.add(user['User id']);
}
}
return usersInManagersGroup;
}
轉載請註明出處，本文鏈接：https://www.uj5u.com/net/516001.html
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