我如何动态地在flutter中的变量上设置数据？

Question

我需要一些帮助。如何在flutter中的变量上动态设置数据？我在listview.builder中有一个表单。动态生成多少个TextFormField。因此，很难为每个TextFormField创建不同的变量。当用户名文本在TextFormField中时，我希望setState该数据在var上，以便我可以将该数据存储在firebase中。这是我的代码的简单版本：

Form(
                  key: _formKey,
                  child: Column(
                    crossAxisAlignment: CrossAxisAlignment.start,
                    children: <Widget>[
                      Expanded(
                        child: ListView.builder(
                            itemCount: widget.stops,

                            itemBuilder: (context, index) {
                              var stops = 1;

                              return Row(
                                children: <Widget>[
                                  Flexible(
                                    child: Container(
                                      child: TextFormField(
                                        decoration: InputDecoration(
                                          labelText: 'Stop ' +
                                              (stops + index).toString(), 
                                        ),
                                        validator: (val) => val.isEmpty
                                            ? 'Cannot be empty'
                                            : null,
                                        onChanged: (val) {
                                          setState(() {
                                             //here i want setdata dynamically
                                         });
                                        },
                                      ),
                                    ),
                                  ),
                                  Flexible(
                                    child: Container(     
                                      child: TextFormField(
                                        cursorColor: Color(0xFF127772),
                                        decoration: InputDecoration(
                                          labelText: 'Ticket Price',
                                            ),
                                          ),
                                        ),
                                        validator: (val) => val.isEmpty
                                            ? 'Cannot be empty'
                                            : null,
                                        onChanged: (val) {
                                          setState(() {
                                            //here i want setdata dynamically
                                          });
                                        },
                                      ),
                                    ),
                                  )
                                ],
                              );
                            }),
                      ),
                      Container(                   
                        child: RaisedButton(
                          ),
                          onPressed: () async {
                            if (_formKey.currentState.validate()) {}
                          },                    
                          child: Text('CREATE'),
                        ),
                      ),
                    ],
                  ),
                ),

Answer 1

您可以在项目中有两个textField时创建两个String列表，并在onsave方法上将val分配给此列表。

以下代码可帮助您更多地理解。

class DeleteWidget extends StatefulWidget {
  final stops = 2;
  @override
  _DeleteWidgetState createState() => _DeleteWidgetState();
}

class _DeleteWidgetState extends State<DeleteWidget> {
  List<String> _list1;
  List<String> _list2;
  GlobalKey<FormState> _formKey = GlobalKey<FormState>();
  @override
  void initState() {
    super.initState();
    _list2 = List(widget.stops);
    _list1 = List(widget.stops);
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Form(
        key: _formKey,
        child: Column(
          children: [
            Expanded(
              child: ListView.builder(
                itemCount: widget.stops,
                itemBuilder: (_, index) {
                  return Row(
                    children: [
                      Flexible(
                        child: TextFormField(
                          validator: (val) =>
                              val.isEmpty ? 'Cannot be empty' : null,
                          onChanged: (val) {
                            setState(
                              () {
                                _list1[index] = val;
                              },
                            );
                          },
                        ),
                      ),
                      SizedBox(
                        width: 20,
                      ),
                      Flexible(
                        child: TextFormField(
                          validator: (val) =>
                              val.isEmpty ? 'Cannot be empty' : null,
                          onChanged: (val) {
                            setState(
                              () {
                                _list2[index] = val;
                              },
                            );
                          },
                        ),
                      )
                    ],
                  );
                },
              ),
            ),
            Container(
              child: RaisedButton(
                onPressed: () async {
                  if (_formKey.currentState.validate()) {
                    _formKey.currentState.save();
                    for (int i = 0; i < widget.stops; i++) {
                      print("item $i form field 1 ${_list1[i]}");
                      print("item $i form field 2 ${_list2[i]}");
                    }
                  }
                },
                child: Text('CREATE'),
              ),
            ),
          ],
        ),
      ),
    );
  }
}