Flutter：如何以编程方式添加 TextField 或 TextFormField

Question

我用 formkey 和 form data 变量创建了一个表单，因为 Map<String, String> _formdata = {}; formdata 包含诸如配置文件数据之类的字段。
其中有一个字段说宠物，它有两个字段名称和年龄。
我想添加一个按钮，允许用户添加更多宠物。此表单仅在单击按钮时可见。用户可以通过单击此按钮添加多个宠物。

class MyPets extends StatefulWidget {
  @override
  _MyPetsState createState() => _MyPetsState();
}

class _MyPetsState extends State<MyPets> {
  Map<String, String> _formdata = {};
  var _myPets = List<Widget>();
  int _index = 1;

  void _add() {
    _myPets = List.from(_myPets)
      ..add(Column(
        children: <Widget>[
          ListTile(
            leading: Text('Pet $_index : '),
            title: TextField(
              onChanged: (val) => _formdata['pet$_index'] = val,
            ),
          ),
          ListTile(
            leading: Text('Name of Pet $_index : '),
            title: TextField(
              onChanged: (val) {
                _formdata['name$_index'] = val;

              },
            ),
          ),
        ],
      ));

    setState(() => ++_index);
  }
@override
  void initState() {
    // TODO: implement initState
    super.initState();
    _add();
  }
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      floatingActionButton: FloatingActionButton(
        onPressed: ()=>print(_formdata),
        child: Text('Save'),
      ),
      appBar: AppBar(
        title: Text('Add your pets'),
        actions: <Widget>[
          FlatButton(
            child: Text('Add another'),
            onPressed: _add,
          ),
        ],
      ),
      body: ListView(
        children: _myPets,
      ),
    );
  }
}

问题是当我打印 _formdata 时，我只得到最后一个值。

{pet6: 5, name6: 5}

Answer 1

让我知道它是否有效。

class MyPets extends StatefulWidget {
  @override
  _MyPetsState createState() => _MyPetsState();
}

class _MyPetsState extends State<MyPets> {
  Map<String, String> _formdata = {};
  var _myPets = List<Widget>();
  int _index = 1;

  void _add() {
    int keyValue = _index;
    _myPets = List.from(_myPets)
      ..add(Column(
        key: Key("${keyValue}"),
        children: <Widget>[
          ListTile(
            leading: Text('Pet $_index : '),
            title: TextField(
              onChanged: (val) => _formdata['pet${keyValue - 1}'] = val,
            ),
          ),
          ListTile(
            leading: Text('Name of Pet $_index : '),
            title: TextField(
              onChanged: (val) {
                _formdata['name${keyValue - 1}'] = val;
              },
            ),
          ),
        ],
      ));

    setState(() => ++_index);
  }

  @override
  void initState() {
    // TODO: implement initState
    super.initState();
    _add();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      floatingActionButton: FloatingActionButton(
        onPressed: () => print(_formdata),
        child: Text('Save'),
      ),
      appBar: AppBar(
        title: Text('Add your pets'),
        actions: <Widget>[
          FlatButton(
            child: Text('Add another'),
            onPressed: _add,
          ),
        ],
      ),
      body: ListView(
        children: _myPets,
      ),
    );
  }
}

Answer 2

由于您没有共享任何代码，因此我将向您介绍如何做到这一点。这是完整的代码。

List<Widget> _children = [];
int _count = 0;

@override
Widget build(BuildContext context) {
  return Scaffold(
    appBar: AppBar(
      title: Text("Title"),
      actions: <Widget>[IconButton(icon: Icon(Icons.add), onPressed: _add)],
    ),
    body: ListView(children: _children),
  );
}

void _add() {
  _children = List.from(_children)
    ..add(TextFormField(
      decoration: InputDecoration(hintText: "This is TextField ${_count}"),
    ));
  setState(() => ++_count);
}