当HookWidget的文本发生变化时，有什么方法可以让我重新构建TextEditingController吗？
当HookWidget的文本发生变化时，有什么方法可以让我重新构建TextEditingController吗？
提问于 2022-03-07 02:42:01
我有一个测试编辑字段。当没有文本时，我想要一个按钮被禁用。当TextField中有文本时，我希望启用按钮。
我使用flutter_hooks来减少控制器的锅炉板代码。
在下面的示例中，当我在文本字段中输入test时，按钮永远不会启用，因为生成没有被触发？当使用带有颤振钩的文本编辑控制器时，如何触发生成？
class MyHomePage extends HookWidget {
const MyHomePage({Key? key}) : super(key: key);
@override
Widget build(BuildContext context) {
var ctrl = useTextEditingController();
VoidCallback? onPressed;
if (ctrl.text.isNotEmpty) {
onPressed = () => print("Pressed!");
}
return Scaffold(
body: Column(
children: [
TextField(
controller: ctrl,
),
ElevatedButton(onPressed: onPressed, child: Text("Button")),
],
)
);
}
}回答 1
Stack Overflow用户
发布于 2022-03-07 04:59:26
您可以使用useState和useTextEditingController来实现这一点。
var istextchanged = useState<bool>(false);
ctrl.addListener(() {
if (ctrl.text.isEmpty) {
istextchanged.value = false;
} else {
istextchanged.value = true;
}
});Yourwidget
class MyHomePages2 extends HookWidget {
const MyHomePages2({Key? key}) : super(key: key);
@override
Widget build(BuildContext context) {
var ctrl = useTextEditingController();
var istextchanged = useState<bool>(false);
ctrl.addListener(() {
if (ctrl.text.isEmpty) {
istextchanged.value = false;
} else {
istextchanged.value = true;
}
});
VoidCallback? onPressed = () {
print("change");
};
if (ctrl.text.isNotEmpty) {
onPressed = () => print("Pressed!");
}
return Scaffold(
body: Column(
children: [
TextField(
controller: ctrl,
onChanged: (v) {},
),
ElevatedButton(
onPressed: istextchanged.value ? onPressed : null,
child: Text("Button"))
],
));
}
}使用flutter_hooks: ^0.18.2+1 钩子的软件包
SampleCode
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:flutter_hooks/flutter_hooks.dart';
Future<void> main() async {
WidgetsFlutterBinding.ensureInitialized();
runApp(MyApp());
}
class MyApp extends StatelessWidget {
const MyApp({Key? key}) : super(key: key);
// This widget is the root of your application.
@override
Widget build(BuildContext context) {
return MaterialApp(
home: MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}
class MyHomePage extends StatefulWidget {
const MyHomePage({Key? key, required this.title}) : super(key: key);
final String title;
@override
State<MyHomePage> createState() => _MyHomePageState();
}
int myvalue = 0;
class _MyHomePageState extends State<MyHomePage> {
int _counter = 0;
@override
void initState() {
// functions().then((int value) {
// setState(() {
// myvalue = value;
// });
// future is completed you can perform your task
// });
}
Future<int> functions() async {
// do something here
return Future.value();
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(),
body: MyHomePages2(),
);
}
}
class MyHomePages2 extends HookWidget {
const MyHomePages2({Key? key}) : super(key: key);
@override
Widget build(BuildContext context) {
var ctrl = useTextEditingController();
var istextchanged = useState<bool>(false);
ctrl.addListener(() {
if (ctrl.text.isEmpty) {
istextchanged.value = false;
} else {
istextchanged.value = true;
}
});
VoidCallback? onPressed = () {
print("change");
};
if (ctrl.text.isNotEmpty) {
onPressed = () => print("Pressed!");
}
return Scaffold(
body: Column(
children: [
TextField(
controller: ctrl,
onChanged: (v) {},
),
ElevatedButton(
onPressed: istextchanged.value ? onPressed : null,
child: Text("Button"))
],
));
}
}页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/71375923
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