Wie füllt man das Flatter-Formularfeld richtig auf?

Question

Ich versuche, eine "Profil bearbeiten" -Seite zu erstellen, wo ich alle Benutzerdaten laden und den Benutzer ändern lassen kann. Die Verwendung der beiden Eigenschaften value und text auf der TextEditingController führt jedoch dazu, dass die Daten in der TextFormField nicht geändert werden können. Ich kann an den Anfang davon hinzufügen, aber ich kann keine Zeichen daraus löschen.

Um dieses Verhalten näher zu erläutern, kann ich im folgenden Screenshot mehr in das Feld eingeben (als ich das "Asdf" gemacht habe), aber von wo der Cursor ist, kann ich den Cursor nicht nach rechts bewegen oder löschen das "F" oder einer der dort ursprünglich platzierten Charaktere.

In der OnSaved Funktion der TextFormField, die value param ist der vollständige Text der Form zum Zeitpunkt der Einreichung, in diesem Fall "AsdfFrederick".

Hier ist mein Code:

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

Hier flutter doctor:

% 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

figured it out: geschaltet TextFormField-TextField, erstellt lokale Variablen Änderungen an den Feldern zu speichern und verwendet initState einstellen Anfangsformularwerte, anstatt es in build zu tun.

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