我正在重新创建一个我以前用 Swift 制作的应用程序，在我的一个页面上，我们调用一个 API，并根据结果，我们向用户显示动态数量的文本字段，以通过不同的搜索参数进行搜索。
在 Dart/Flutter 中有什么好的方法可以做到这一点吗？由于 dart 不支持在运行时生成代码，这甚至有可能吗？
【问题讨论】：
我刚刚修改了@Felix 的答案，使用 Map 来存储 TextEditingControllers 而不是列表。我认为用键值对调用 textEditingControllers 很容易。 修改代码块；
import 'package:flutter/material.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
title: "MyHomePage",
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: MyHomePage(
title: "MyHomePage",
),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
final title;
@override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
@override
Widget build(BuildContext context) {
var stringListReturnedFromApiCall = ["first", "second", "third", "fourth", "..."];
// This list of controllers can be used to set and get the text from/to the TextFields
Map<String,TextEditingController> textEditingControllers = {};
var textFields = <TextField>[];
stringListReturnedFromApiCall.forEach((str) {
var textEditingController = new TextEditingController(text: str);
textEditingControllers.putIfAbsent(str, ()=>textEditingController);
return textFields.add( TextField(controller: textEditingController));
});
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: SingleChildScrollView(
child: new Column(
children:[
Column(children: textFields),
RaisedButton(
child: Text("Print Values"),
onPressed: (){
stringListReturnedFromApiCall.forEach((str){
print(textEditingControllers[str].text);
});
})
]
)));
}
}
当您向文本字段写入内容并点击打印按钮结果时；
flutter: first controller text
flutter: second controller text
flutter: third controller text
flutter: fourth controller text
flutter: so on .......
【讨论】：
或多或少就像@Günter Zöchbauer 提到的那样，您可以构建一个嵌套在容器中的小部件列表。
这是一个简单的例子：
import 'package:flutter/material.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
title: "MyHomePage",
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: MyHomePage(
title: "MyHomePage",
),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
final title;
@override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
@override
Widget build(BuildContext context) {
var stringListReturnedFromApiCall = ["first", "second", "third", "fourth", "..."];
// This list of controllers can be used to set and get the text from/to the TextFields
var textEditingControllers = <TextEditingController>[];
var textFields = <TextField>[];
stringListReturnedFromApiCall.forEach((str) {
var textEditingController = new TextEditingController(text: str);
textEditingControllers.add(textEditingController);
return textFields.add(new TextField(controller: textEditingController));
});
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: SingleChildScrollView(
child: new Column(
children: textFields,
)));
}
}
编辑：为TextEditingControllers 添加列表以与所有TextFields 交互
【讨论】：
TextEditingController是没有用的。 TextEditingController 通常用于从 TextField 获取文本并将文本设置为 TextField，而这些不能用这个来完成。
TextEditingController可以用来定义TextField的默认值以及从中获取值。 TextFields，没有完整的实现。
textEditingControllers-list 并访问text 属性以读取当前值。
使用 textEditingControllers 列表代替地图
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
final title;
@override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
var stringListReturnedFromApiCall = ["first", "second", "third", "fourth", "..."];
List<TextEditingController> textEditingControllers = [];
@override
void initState() {
super.initState();
stringListReturnedFromApiCall.forEach((String str) {
var textEditingController = TextEditingController(text: str);
textEditingControllers.add(textEditingController);
});
}
@override
void dispose() {
super.dispose();
// dispose textEditingControllers to prevent memory leaks
for (TextEditingController textEditingController in textEditingControllers) {
textEditingController?.dispose();
}
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('title'),
),
body: ListView.builder(
itemCount: stringListReturnedFromApiCall.length,
itemBuilder: (BuildContext context, int index) {
return Padding(
padding: const EdgeInsets.all(10.0),
child: TextField(
controller: textEditingControllers[index],
),
);
},
),
);
}
}
【讨论】：
这可能对您或其他人也有帮助。
createFieldsList(context) {
thirdStepUserRegistration.value.forEach((key, value) { //// This line will loop all your data [ValueNotifier<Map<String, dynamic>> thirdStepUserRegistration]
if (!fieldsController.containsKey(key)) {
fieldsController[key] = TextEditingController(); //// This one will create you a list of controllers that u need for your fiels [Map<String, TextEditingController> fieldsController]
fieldsList.add( ////You will be creating a list of widget which is textfields [List<Widget> fieldsList]
Container(
height: 40.0,
margin: EdgeInsets.only(bottom: 10),
width: MediaQuery.of(context).size.width - 100,
child: PrimaryTextFormField( //This is my customize textfield you can create yours
controller: fieldsController[key],
keyboardType: TextInputType.text,
textCapitalization: TextCapitalization.words,
inputFormatters: textFormatter(),
hintText: value,
),
)
);
}
});
}
Column additionalDetails(BuildContext context) {
createFieldsList(context);
return Column( children: fieldsList );
}
【讨论】：
包含您的控制器的列表
var myControllers = [];
为了填充 myControllers 而调用的函数
createControllers() { myControllers = []; for (var i = 0; i < your_items.length; i++) { myControllers.add(TextEditingController()); } }
在你的 statefullwidget 中初始化 createKeys 像这样使用它，例如在 listview builder 中；
TextField( controller: myControllers[index], ),
【讨论】：