フラッタフォームフィールドを正しく事前に入力するにはどうすればよいですか？

Question

私はすべてのユーザーデータを読み込み、ユーザーに変更させる "プロファイルの編集"ページを作成しようとしています。しかし、TextEditingControllerのvalueとtextの両方のプロパティを使用すると、TextFormFieldのデータを変更できなくなります。私はそれの先頭に追加することができますが、私はそれから任意の文字を削除することはできません。

以下のスクリーンショットで、私は "Asdf"のようにフィールドにmoreを入力できますが、カーソルがある場所からカーソルを右に移動したり削除したりすることはできません「F」またはそれに元々置かれていた文字のいずれか。 TextFormFieldのOnSaved関数で

、value PARAMは、この場合、「AsdfFrederick」、提出時の形の全文です。ここで

は私のコードです：

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

ここflutter doctorです：

% 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) 

Answer 1

はそれを考え出した：、TextFieldへTextFormFieldから切り替えフィールドへの変更を保存するために、ローカル変数を作成し、設定するためにinitStateを使用しました最初のフォームの値はbuildで行うのではなく、

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