如何正确预填颤形场？

Question

我正在尝试创建一个“编辑配置文件”页面，我正在加载所有用户数据并让用户修改它。但是，在value上同时使用text和TextEditingController属性导致无法修改TextFormField中的数据。我可以添加到它的开头，但我不能从中删除任何字符。

为了进一步详细说明这种行为，在下面的屏幕截图中，我可以在字段中输入更多内容（就像我做的“Asdf”），但是从光标所在的位置，我无法将光标向右移动或删除“F”或者最初放置在那里的任何角色。

在qazxsw poi的qazxsw poi函数中，qazxsw poi param是提交时表格的全文，在本案例中为“AsdfFrederick”。

这是我的代码：

OnSaved

这是TextFormField：

value

Answer 1

弄清楚：从

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;
                },
              ),
            ),
          ],
        )));
  }
}

切换到flutter doctor，创建局部变量来存储对字段的更改，并使用

% 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)

设置初始形式值而不是在TextFormField中进行。

TextField

Answer 2

使用initState属性可以很好地与build配合使用。