Forms 如何从另一个dart文件调用有状态小部件(具有表单)方法
我在有状态小部件中有一个表单,在有状态小部件中我用提交方法验证表单 在我的应用程序中,我在另一个dart文件的另一个页面中显示该表单Forms 如何从另一个dart文件调用有状态小部件(具有表单)方法,forms,flutter,dart,statefulwidget,Forms,Flutter,Dart,Statefulwidget,我在有状态小部件中有一个表单,在有状态小部件中我用提交方法验证表单 在我的应用程序中,我在另一个dart文件的另一个页面中显示该表单 我的表单在新页面和appbar操作中可见,我正在调用submit方法,但我不知道如何在新dart文件中调用submit方法。您可以在另一个小部件的顶部创建VoidCallback final,这将触发父小部件的操作 class FormWidget extends StatefulWidget { @override _FormWidgetState cr
我的表单在新页面和appbar操作中可见,我正在调用submit方法,但我不知道如何在新dart文件中调用submit方法。您可以在另一个小部件的顶部创建VoidCallback final,这将触发父小部件的操作
class FormWidget extends StatefulWidget {
@override
_FormWidgetState createState() => _FormWidgetState();
}
class _FormWidgetState extends State<FormWidget> {
@override
Widget build(BuildContext context) {
return Column(
children: <Widget>[
//here goes your form and everything else
SubmitButton(
onClick: (){
//perform the actions you need
},
),
],
);
}
}
class SubmitButton extends StatelessWidget {
final VoidCallback onClick;
const SubmitButton({Key key, this.onClick}) : super(key: key);
@override
Widget build(BuildContext context) {
return GestureDetector(
onTap: onClick,
child:Container(
//your button
),
);
}
}
class FormWidget扩展了StatefulWidget{
@凌驾
_FormWidgetState createState();
}
类_FormWidgetState扩展状态{
@凌驾
小部件构建(构建上下文){
返回列(
儿童:[
//这是你的表格和其他一切
提交按钮(
onClick:(){
//执行您需要的操作
},
),
],
);
}
}
类SubmitButton扩展了无状态小部件{
最后一次点击;
const SubmitButton({Key-Key,this.onClick}):super(Key:Key);
@凌驾
小部件构建(构建上下文){
返回手势检测器(
onTap:onClick,
子:容器(
//你的钮扣
),
);
}
}
我认为您的问题不是验证逻辑,您可以在回调中执行我认为您的情况是,单击提交按钮时,您可以使用SnackBar。您使用SnackBar显示错误,并且不希望在appbar中重复此逻辑
诀窍是使用GlobalKey保持您的formstate,并使用key.currentState在您的formstate中调用函数,因此submit按钮和appbar操作可以调用相同的函数
final key = new GlobalKey<MyCustomFormState>();
...
appBar: AppBar(
title: Text(widget.title),
actions: <Widget>[
// action button
IconButton(
icon: Icon(Icons.access_alarm),
onPressed: () {
key.currentState.validateform();
},
),
]),
...
children: <Widget>[
MyCustomForm(key: key),
...
class MyCustomForm extends StatefulWidget {
MyCustomForm({ Key key }) : super(key: key);
final key=new GlobalKey();
...
appBar:appBar(
标题:文本(widget.title),
行动:[
//动作按钮
图标按钮(
图标:图标(图标访问报警),
已按下:(){
key.currentState.validateform();
},
),
]),
...
儿童:[
MyCustomForm(键:键),
...
类MyCustomForm扩展了StatefulWidget{
MyCustomForm({Key}):超级(Key:Key);
完整工作代码
import 'package:flutter/material.dart';
void main() => runApp(MyApp());
final key = new GlobalKey<MyCustomFormState>();
class MyApp extends StatelessWidget {
// This widget is the root of your application.
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
// This is the theme of your application.
//
// Try running your application with "flutter run". You'll see the
// application has a blue toolbar. Then, without quitting the app, try
// changing the primarySwatch below to Colors.green and then invoke
// "hot reload" (press "r" in the console where you ran "flutter run",
// or simply save your changes to "hot reload" in a Flutter IDE).
// Notice that the counter didn't reset back to zero; the application
// is not restarted.
primarySwatch: Colors.blue,
),
home: MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
// This widget is the home page of your application. It is stateful, meaning
// that it has a State object (defined below) that contains fields that affect
// how it looks.
// This class is the configuration for the state. It holds the values (in this
// case the title) provided by the parent (in this case the App widget) and
// used by the build method of the State. Fields in a Widget subclass are
// always marked "final".
final String title;
@override
_MyHomePageState createState() => _MyHomePageState();
}
var myCustomForm = MyCustomForm();
class _MyHomePageState extends State<MyHomePage> {
int _counter = 0;
void _incrementCounter() {
setState(() {
// This call to setState tells the Flutter framework that something has
// changed in this State, which causes it to rerun the build method below
// so that the display can reflect the updated values. If we changed
// _counter without calling setState(), then the build method would not be
// called again, and so nothing would appear to happen.
_counter++;
});
}
@override
Widget build(BuildContext context) {
// This method is rerun every time setState is called, for instance as done
// by the _incrementCounter method above.
//
// The Flutter framework has been optimized to make rerunning build methods
// fast, so that you can just rebuild anything that needs updating rather
// than having to individually change instances of widgets.
return Scaffold(
appBar: AppBar(
// Here we take the value from the MyHomePage object that was created by
// the App.build method, and use it to set our appbar title.
title: Text(widget.title),
actions: <Widget>[
// action button
IconButton(
icon: Icon(Icons.access_alarm),
onPressed: () {
key.currentState.validateform();
},
),
]),
body: Center(
// Center is a layout widget. It takes a single child and positions it
// in the middle of the parent.
child: Column(
// Column is also layout widget. It takes a list of children and
// arranges them vertically. By default, it sizes itself to fit its
// children horizontally, and tries to be as tall as its parent.
//
// Invoke "debug painting" (press "p" in the console, choose the
// "Toggle Debug Paint" action from the Flutter Inspector in Android
// Studio, or the "Toggle Debug Paint" command in Visual Studio Code)
// to see the wireframe for each widget.
//
// Column has various properties to control how it sizes itself and
// how it positions its children. Here we use mainAxisAlignment to
// center the children vertically; the main axis here is the vertical
// axis because Columns are vertical (the cross axis would be
// horizontal).
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
MyCustomForm(key: key),
Text(
'You have pushed the button this many times:',
),
Text(
'$_counter',
style: Theme.of(context).textTheme.display1,
),
],
),
),
floatingActionButton: FloatingActionButton(
onPressed: _incrementCounter,
tooltip: 'Increment',
child: Icon(Icons.add),
), // This trailing comma makes auto-formatting nicer for build methods.
);
}
}
class MyCustomForm extends StatefulWidget {
MyCustomForm({ Key key }) : super(key: key);
@override
MyCustomFormState createState() {
return MyCustomFormState();
}
}
// Create a corresponding State class.
// This class holds data related to the form.
class MyCustomFormState extends State<MyCustomForm> {
// Create a global key that uniquely identifies the Form widget
// and allows validation of the form.
//
// Note: This is a GlobalKey<FormState>,
// not a GlobalKey<MyCustomFormState>.
final _formKey = GlobalKey<FormState>();
@override
Widget build(BuildContext context) {
// Build a Form widget using the _formKey created above.
return Form(
key: _formKey,
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
TextFormField(
validator: (value) {
if (value.isEmpty) {
return 'Please enter some text';
}
return null;
},
),
Padding(
padding: const EdgeInsets.symmetric(vertical: 16.0),
child: RaisedButton(
onPressed: () {
// Validate returns true if the form is valid, or false
// otherwise.
validateform();
},
child: Text('Submit'),
),
),
],
),
);
}
void validateform() {
// Validate returns true if the form is valid, or false
// otherwise.
if (_formKey.currentState.validate()) {
// If the form is valid, display a Snackbar.
Scaffold.of(context)
.showSnackBar(SnackBar(content: Text('Processing Data')));
}
}
}
导入“包装:颤振/材料.省道”;
void main()=>runApp(MyApp());
final key=new GlobalKey();
类MyApp扩展了无状态小部件{
//此小部件是应用程序的根。
@凌驾
小部件构建(构建上下文){
返回材料PP(
标题:“颤振演示”,
主题:主题数据(
//这是应用程序的主题。
//
//尝试使用“flutter run”运行应用程序。您将看到
//应用程序有一个蓝色工具栏。然后,在不退出应用程序的情况下,重试
//将下面的primarySwatch更改为Colors.green,然后调用
//“热重新加载”(在运行“颤振运行”的控制台中按“r”,
//或者只需将更改保存到颤振IDE中的“热重新加载”。
//请注意,计数器没有重置回零;应用程序
//未重新启动。
主样本:颜色。蓝色,
),
主页:MyHomePage(标题:“颤振演示主页”),
);
}
}
类MyHomePage扩展StatefulWidget{
MyHomePage({Key,this.title}):超级(Key:Key);
//此小部件是应用程序的主页。它是有状态的,表示
//它有一个状态对象(定义如下),其中包含影响
//看起来怎么样。
//此类是状态的配置。它保存值(在此
//案例名称)由家长(在本例中为应用程序小部件)提供,以及
//由State的build方法使用。小部件子类中的字段包括
//始终标记为“最终”。
最后的字符串标题;
@凌驾
_MyHomePageState createState()=>\u MyHomePageState();
}
var myCustomForm=myCustomForm();
类_MyHomePageState扩展状态{
int _计数器=0;
void _incrementCounter(){
设置状态(){
//这个对setState的调用告诉颤振框架,某些东西
//已在此状态下更改,这将导致它重新运行下面的生成方法
//以便显示能够反映更新的值。如果我们更改
//_计数器,而不调用setState(),则生成方法将不可用
//再打一次电话,似乎什么也没发生。
_计数器++;
});
}
@凌驾
小部件构建(构建上下文){
//每次调用setState时都会重新运行此方法,例如,按done
//通过上面的_incrementCounter方法。
//
//对颤振框架进行了优化,以制定重新运行的构建方法
//快速,这样你就可以重建任何需要更新的东西
//而不是必须单独更改小部件的实例。
返回脚手架(
appBar:appBar(
//在这里,我们从MyHomePage对象中获取由创建的值
//使用App.build方法,并使用它设置appbar标题。
标题:文本(widget.title),
行动:[
//动作按钮
图标按钮(
图标:图标(图标访问报警),
已按下:(){
key.currentState.validateform();
},
),
]),
正文:中(
//中心是一个布局小部件。它接受一个子元素并对其进行定位
/在父母的中间。
子:列(
//列也是一个布局小部件,它包含一系列子项和
//垂直排列。默认情况下,它会调整自身大小以适应其位置
//孩子们水平移动,并试图和父母一样高。
//
//调用“调试绘制”(在控制台中按“p”,选择
//Android中颤振检查器的“切换调试绘制”操作
//或Visual Studio代码中的“切换调试绘制”命令)
//查看每个小部件的线框。
//
//列具有各种属性来控制其自身大小和大小