我试图创建一个“编辑配置文件”页面，在这里我加载所有用户数据，并允许用户修改它。但是，同时使用value和text属性会导致无法修改TextEditingController中的数据。我可以在开头添加，但不能从中删除任何字符。
为了进一步阐述这种行为，在下面的屏幕截图中，我可以在字段中键入更多内容（正如我所做的“asdf”），但从光标所在的位置，我不能将光标向右移动，也不能删除“f”或原来放置在其中的任何字符。
在TextFormField的OnSaved函数中，TextFormField参数是提交时表单的全文，在本例中为“asdffrederick”。
这是我的代码：
import 'dart:async';
import 'package:flutter/material.dart';
import '../models/user.dart';
class EditProfileView extends StatefulWidget {
@override
_EditProfileViewState createState() => new _EditProfileViewState();
}
class _EditProfileViewState extends State<EditProfileView> {
final GlobalKey<FormState> _formKey = new GlobalKey<FormState>();
void _handleSubmitted() {
final FormState form = _formKey.currentState;
if (!form.validate()) {
} else {
form.save();
User.instance.save().then((result) {
print("Saving done: ${result}.");
Navigator.pop(context);
});
}
}
@override
Widget build(BuildContext context) {
final ThemeData themeData = Theme.of(context);
final DateTime today = new DateTime.now();
// controllers for form text controllers
final TextEditingController _firstNameController =
new TextEditingController();
//_firstNameController.value = new TextEditingValue(text: User.instance.first_name);
_firstNameController.text = User.instance.first_name;
final TextEditingController _lastNameController =
new TextEditingController();
_lastNameController.text = User.instance.last_name;
return new Scaffold(
appBar: new AppBar(title: const Text('Edit Profile'), actions: <Widget>[
new Container(
padding: const EdgeInsets.fromLTRB(0.0, 10.0, 5.0, 10.0),
child: new MaterialButton(
color: themeData.primaryColor,
textColor: themeData.secondaryHeaderColor,
child: new Text('Save'),
onPressed: () {
_handleSubmitted();
Navigator.pop(context);
},
))
]),
body: new Form(
key: _formKey,
autovalidate: _autovalidate,
onWillPop: _warnUserAboutInvalidData,
child: new ListView(
padding: const EdgeInsets.symmetric(horizontal: 16.0),
children: <Widget>[
new Container(
child: new TextFormField(
decoration: const InputDecoration(labelText: "First Name", hintText: "What do people call you?"),
autocorrect: false,
controller: _firstNameController,
onSaved: (String value) {
User.instance.first_name = value;
},
),
),
new Container(
child: new TextFormField(
decoration: const InputDecoration(labelText: "Last Name"),
autocorrect: false,
controller: _lastNameController,
onSaved: (String value) {
User.instance.last_name = value;
},
),
),
],
)));
}
}
这里是：
% flutter doctor
[✓] Flutter (on Mac OS X 10.12.6 16G29, locale en-US, channel alpha)
• Flutter at /Users/frederickcook/flutter
• Framework revision 701d534ba9 (2 weeks ago), 2017-09-12 14:01:51 -0700
• Engine revision 31d03de019
• Tools Dart version 1.25.0-dev.11.0
[✓] Android toolchain - develop for Android devices (Android SDK 26.0.0)
• Android SDK at /Users/frederickcook/Library/Android/sdk
• Platform android-26, build-tools 26.0.0
• Java binary at: /Applications/Android Studio.app/Contents/jre/jdk/Contents/Home/bin/java
• Java version OpenJDK Runtime Environment (build 1.8.0_112-release-b06)
[✓] iOS toolchain - develop for iOS devices (Xcode 9.0)
• Xcode at /Applications/Xcode.app/Contents/Developer
• Xcode 9.0, Build version 9A235
• ios-deploy 1.9.2
• CocoaPods version 1.2.1
[✓] Android Studio (version 2.3)
• Android Studio at /Applications/Android Studio.app/Contents
• Java version OpenJDK Runtime Environment (build 1.8.0_112-release-b06)
[✓] IntelliJ IDEA Community Edition (version 2017.2.5)
• Flutter plugin version 17.0
• Dart plugin version 172.4155.35
[✓] Connected devices
• iPhone 7 • 2AE532E3-5B4B-4D8D-8CFB-F54C3BF6F8EE • ios • iOS 11.0 (simulator)
最佳答案
计算出来：从TextFormField切换到TextField，创建局部变量来存储对字段的更改，并使用initState来设置初始表单值，而不是在build中进行设置。
import 'dart:async';
import 'package:flutter/material.dart';
import '../models/user.dart';
class EditProfileView extends StatefulWidget {
@override
_EditProfileViewState createState() => new _EditProfileViewState();
}
class _EditProfileViewState extends State<EditProfileView> {
final GlobalKey<FormState> _formKey = new GlobalKey<FormState>();
void _handleSubmitted() {
final FormState form = _formKey.currentState;
if (!form.validate()) {
_autovalidate = true; // Start validating on every change.
showInSnackBar('Please fix the errors in red before submitting.');
} else {
showInSnackBar('snackchat');
User.instance.first_name = firstName;
User.instance.last_name = lastName;
User.instance.save().then((result) {
print("Saving done: ${result}.");
});
}
}
// controllers for form text controllers
final TextEditingController _firstNameController = new TextEditingController();
String firstName = User.instance.first_name;
final TextEditingController _lastNameController = new TextEditingController();
String lastName = User.instance.last_name;
@override
void initState() {
_firstNameController.text = firstName;
_lastNameController.text = lastName;
return super.initState();
}
@override
Widget build(BuildContext context) {
final ThemeData themeData = Theme.of(context);
final DateTime today = new DateTime.now();
return new Scaffold(
appBar: new AppBar(title: const Text('Edit Profile'), actions: <Widget>[
new Container(
padding: const EdgeInsets.fromLTRB(0.0, 10.0, 5.0, 10.0),
child: new MaterialButton(
color: themeData.primaryColor,
textColor: themeData.secondaryHeaderColor,
child: new Text('Save'),
onPressed: () {
_handleSubmitted();
Navigator.pop(context);
},
))
]),
body: new Form(
key: _formKey,
autovalidate: _autovalidate,
onWillPop: _warnUserAboutInvalidData,
child: new ListView(
padding: const EdgeInsets.symmetric(horizontal: 16.0),
children: <Widget>[
new Container(
child: new TextField(
decoration: const InputDecoration(labelText: "First Name", hintText: "What do people call you?"),
autocorrect: false,
controller: _firstNameController,
onChanged: (String value) {
firstName = value;
},
),
),
new Container(
child: new TextField(
decoration: const InputDecoration(labelText: "Last Name"),
autocorrect: false,
controller: _lastNameController,
onChanged: (String value) {
lastName = value;
},
),
),
],
)));
}
}
关于forms - 如何正确预填颤形场？，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/46481638/