[英]How do avoid markNeedsBuilder() error using Flutter_Riverpod and TextEditingControllers on TextFormFields?
下面的表格使用來自 flutter_riverpod package 的 ConsumerWidget 來觀察 firebase stream 提供程序中名字/姓氏字段的更新。 然后使用 TextEditingControllers 在字段中設置watch
ed 文本值,並在更新 Firebase 中的帳戶時獲取文本值。
這一切都很好,直到我直接在 Firebase 中更改名字或姓氏字段中的值,這會導致 ui 中的重建。 雖然 UI 確實顯示更新 Firebase 值,但我在運行日志中收到以下異常。
似乎riverpod 正在與state 上的TextEditingControllers 作戰,這是有道理的,但是我該如何克服呢?
========基礎庫捕獲的異常===================================== =============== 在為 TextEditingController 分派通知時引發以下斷言:在構建期間調用 setState() 或 markNeedsBuild()。
無法將此表單小部件標記為需要構建,因為框架已經在構建小部件的過程中。 僅當其祖先之一當前正在構建時,小部件才能在構建階段標記為需要構建。 這個例外是允許的,因為框架在子組件之前構建父窗口小部件,這意味着將始終構建臟后代。 否則,框架可能不會在此構建階段訪問此小部件。 調用 setState() 或 markNeedsBuild() 的小部件是:Form-[LabeledGlobalKey#78eaf] state:FormState#7d070 發出違規調用時當前正在構建的小部件是:FirstLastName 臟依賴項:[UncontrolledProviderScope]
account_setup.dart
class AccountSetup extends StatefulWidget {
@override
_AccountSetupState createState() => _AccountSetupState();
}
class _AccountSetupState extends State<AccountSetup> {
final TextEditingController _firstNameController = TextEditingController();
final TextEditingController _lastNameController = TextEditingController();
@override
void initState() {
super.initState();
}
@override
void dispose() {
_firstNameController.dispose();
_lastNameController.dispose();
super.dispose();
}
final _formKey = GlobalKey<FormState>();
@override
Widget build(BuildContext context) {
return SafeArea(
child: Scaffold(
backgroundColor: Colors.white,
body: Form(
key: _formKey,
child: ListView(
children: [
AccountSettingsTitle(
title: 'Account Setup',
),
FirstLastName(_firstNameController, _lastNameController),
SizedBox(
height: 24.0,
),
],
),
),
),
);
}
}
class FirstLastName extends ConsumerWidget {
FirstLastName(
this.firstNameController,
this.lastNameController,
);
final TextEditingController firstNameController;
final TextEditingController lastNameController;
@override
Widget build(BuildContext context, ScopedReader watch) {
final account = watch(accountStreamProvider);
return account.when(
data: (data) {
firstNameController.text = data.firstName;
lastNameController.text = data.lastName;
return Column(
children: [
Center(
child: Padding(
padding: EdgeInsets.only(top: 10.0, left: 24.0, right: 24.0),
child: TextFormField(
controller: firstNameController,
decoration: kInputStringFields.copyWith(
hintText: 'First Name',
),
autocorrect: false,
validator: (String value) {
if (value.isEmpty) {
return 'Enter first name';
}
return null;
},
),
),
),
SizedBox(
height: 14.0,
),
Center(
child: Padding(
padding: EdgeInsets.only(top: 10.0, left: 24.0, right: 24.0),
child: TextFormField(
controller: lastNameController,
decoration: kInputStringFields.copyWith(
hintText: 'Last Name',
),
autocorrect: false,
validator: (String value) {
if (value.isEmpty) {
return 'Enter last name';
}
return null;
},
),
),
),
],
);
},
loading: () => Container(),
error: (_, __) => Container(),
);
}
}
top_level_providers.dart
final accountStreamProvider = StreamProvider.autoDispose<Account>((ref) {
final database = ref.watch(databaseProvider);
return database != null ? database.accountStream() : const Stream.empty();
});
為 TextEditingController 發送通知時拋出了斷言:在構建期間調用了 setState() 或 markNeedsBuild()。
當您在構建方法中更新 CahngeNotifier 時會顯示此錯誤,在這種情況下,當您構建小部件時會更新 TextEditingController:
firstNameController.text = data.firstName;
lastNameController.text = data.lastName;
....
正如您所提到的, hooks_riverpod
可能是一種選擇,但如果您不想在完全了解riverpod 或state 管理之前用圖書館淹沒自己,我會推薦兩種方法:
嘗試使用ProviderListener
(flutter_riverpod 的一部分):
class AccountSetup extends StatefulWidget {
@override
_AccountSetupState createState() => _AccountSetupState();
}
class _AccountSetupState extends State<AccountSetup> {
final TextEditingController _firstNameController = TextEditingController();
final TextEditingController _lastNameController = TextEditingController();
@override
void initState() {
super.initState();
}
@override
void dispose() {
_firstNameController.dispose();
_lastNameController.dispose();
super.dispose();
}
final _formKey = GlobalKey<FormState>();
@override
Widget build(BuildContext context) {
return SafeArea(
child: Scaffold(
backgroundColor: Colors.white,
body: Form(
key: _formKey,
child: ListView(
children: [
AccountSettingsTitle(
title: 'Account Setup',
),
ProviderListener<AsyncValue>(
provider: accountStreamProvider,
onChange: (context, account) { //This will called when accountStreamProvider updates and a frame after the widget rebuilt
if(account is AsyncData) {
firstNameController.text = data.firstName;
lastNameController.text = data.lastName;
}
},
child: FirstLastName(_firstNameController, _lastNameController),
),
SizedBox(
height: 24.0,
),
],
),
),
),
);
}
}
或者您可以在FirstLastName
中使用它並包裝小部件結果,它應該工作相同(請記住刪除行firstNameController.text = data.firstName;
和lastNameController.text = data.lastName;
在when.data
內以防止錯誤)
@override
Widget build(BuildContext context, ScopedReader watch) {
final account = watch(accountStreamProvider);
return ProviderListener<AsyncValue>(
provider: accountStreamProvider,
onChange: (context, account) { //This will called when accountStreamProvider updates and a frame after the widget rebuilt
if(account is AsyncData) {
firstNameController.text = data.firstName;
lastNameController.text = data.lastName;
}
},
child: account.maybeWhen(
data: (data) {
/// don't call firstNameController.text = data.firstName here
return Column(
children: [
....
],
);
},
orElse: () => Container(),
),
);
}
}
另一種選擇是使用 Riverpod 創建您自己的TextEditingController
,並在創建時使用 stream 的數據對其進行更新:
final firstNameProvider = ChangeNotifierProvider.autoDispose<TextEditingController>((ref) {
final account = ref.watch(accountStreamProvider);
final String name = account.maybeWhen(
data: (data) => data?.firstName,
orElse: () => null,
);
return TextEditingController(text: name);
});
final lastNameProvider = ChangeNotifierProvider.autoDispose<TextEditingController>((ref) {
final account = ref.watch(accountStreamProvider);
final String lastName = account.maybeWhen(
data: (data) => data?.lastName,
orElse: () => null,
);
return TextEditingController(text: lastName);
});
然后不要在父 StatefulWidget 中創建它們,只需在FirstLastName();
(不再需要在構造函數中傳遞 TextEditingControllers 了)
class FirstLastName extends ConsumerWidget {
const FirstLastName({Key key}) : super(key: key);
@override
Widget build(BuildContext context, ScopedReader watch) {
final account = watch(accountStreamProvider);
return account.maybeWhen(
data: (data) {
return Column(
children: [
Center(
child: Padding(
padding: EdgeInsets.only(top: 10.0, left: 24.0, right: 24.0),
child: Consumer(
builder: (context, watch, child) {
final firstNameController = watch(firstNameProvider); //call it here
return TextFormField(
controller: firstNameController,
decoration: kInputStringFields.copyWith(
hintText: 'First Name',
),
autocorrect: false,
validator: (String value) {
if (value.isEmpty) {
return 'Enter first name';
}
return null;
},
);
}
),
),
),
SizedBox(
height: 14.0,
),
Center(
child: Padding(
padding: EdgeInsets.only(top: 10.0, left: 24.0, right: 24.0),
child: child: Consumer(
builder: (context, watch, child) {
final lastNameController = watch(lastNameProvider); //call it here
return TextFormField(
controller: lastNameController ,
decoration: kInputStringFields.copyWith(
hintText: 'LAst Name',
),
autocorrect: false,
validator: (String value) {
if (value.isEmpty) {
return 'Enter first name';
}
return null;
},
);
}
),
),
),
],
);
},
orElse: () => Container(),
);
}
}
問題是您在其構建方法執行期間使用以下行觸發了小部件的重建:
firstNameController.text = data.firstName;
lastNameController.text = data.lastName;
然而,解決方案非常簡單。 只需用零延遲的 Future 包裝它:
Future.delayed(Duration.zero, (){
firstNameController.text = data.firstName;
lastNameController.text = data.lastName;
});
基本上,總是當你看到這個錯誤時,你需要在構建期間找到觸發重建的代碼並將其包裝在 Future
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