我是Flutter的新手，正尝试使用Dynamic FormField构建应用程序，问题是dropdownformfield值未随索引更新。但是，使用textformfield可以使用，但不能与Dropdownformfield一起使用
当您按+按钮时，会出现一个新行，但是如果您查看dropdownformfield，则该值将变为空白，并且不会随该行更新。
这是代码。
class DynamicWidgets extends StatefulWidget {
@override
_DynamicWidgetState createState() => _DynamicWidgetState();
}
class _DynamicWidgetState extends State<DynamicWidgets> {
final _formKey = GlobalKey<FormState>();
TextEditingController _nameController;
static List<String> dropdowndata=[null];
static List<String> descriotiondata=[null];
@override
void initState() {
// TODO: implement initState
super.initState();
_nameController = TextEditingController();
_nameController.text = "XR";
}
@override
void dispose() {
_nameController.dispose();
super.dispose();
}
@override
Widget build(BuildContext context) {
// TODO: implement build
return Form(
key: _formKey,
child: Padding(
padding: const EdgeInsets.all(16.0),
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: [
Padding(
padding: const EdgeInsets.only(right: 32.0),
child: TextFormField(
controller: _nameController,
decoration: InputDecoration(hintText: 'Modality Name'),
validator: (v) {
if (v.trim().isEmpty) return 'Please enter something';
return null;
},
),
),
Text("Add More Study"),
SizedBox(
height: 5,
),
..._getFields(),
SizedBox(
height: 10,
),
FlatButton(
onPressed: () {
if (_formKey.currentState.validate()) {
_formKey.currentState.save();
debugPrint("Widget1 Key data: ${dropdowndata.toString()}");
debugPrint("Widget2 Key data: ${descriotiondata.toString()}");
}
},
child: Text(
'Submit',
style: TextStyle(color: Colors.white),
),
color: Colors.green,
),
],
),
),
);
throw UnimplementedError();
}
List<Widget> _getFields() {
List<Widget> friendsTextFields = [];
for (int i = 0; i < dropdowndata.length; i++) {
friendsTextFields.add(Padding(
padding: const EdgeInsets.symmetric(vertical: 16.0),
child: Row(
children: [
Expanded(child: DynamicFields(i)),
SizedBox(
width: 16,
),
// we need add button at last friends row
_addRemoveButton(i == dropdowndata.length - 1, i),
],
),
));
}
return friendsTextFields;
}
Widget _addRemoveButton(bool add, int index) {
return InkWell(
onTap: () {
if (add) {
// add new text-fields at the top of all friends textfields
dropdowndata.insert(0, null);
descriotiondata.insert(0, null);
} else {
dropdowndata.removeAt(index);
descriotiondata.removeAt(index);
}
setState(() {});
},
child: Container(
width: 30,
height: 30,
decoration: BoxDecoration(
color: (add) ? Colors.green : Colors.red,
borderRadius: BorderRadius.circular(20),
),
child: Icon(
(add) ? Icons.add : Icons.remove,
color: Colors.white,
),
),
);
}
}
class DynamicFields extends StatefulWidget {
final int index;
DynamicFields(this.index);
@override
_DynamicFieldsState createState() => _DynamicFieldsState();
}
class _DynamicFieldsState extends State<DynamicFields>{
TextEditingController _descriptionController;
var _selectedValue;
var _dropdownvalue;
String _myActivity;
String _myActivityResult;
static var _studynames = ["CT-62", "CT-53","CT-54","CT-50"];
@override
void initState() {
// TODO: implement initState
super.initState();
this._descriptionController=TextEditingController();
}
@override
void dispose() {
_descriptionController.dispose();
super.dispose();
}
@override
Widget build(BuildContext context) {
WidgetsBinding.instance.addPostFrameCallback((timeStamp) {
_descriptionController.text = _DynamicWidgetState.descriotiondata[widget.index] ?? '';
_selectedValue=_DynamicWidgetState.dropdowndata[widget.index] ?? '';
});
// TODO: implement build
return Row(
children: [
Flexible(
flex: 1,
child: Container(
margin: EdgeInsets.all(5.0),
decoration: BoxDecoration(
borderRadius: BorderRadius.circular(5.0),
border: Border.all(
color: Colors.blueGrey, style: BorderStyle.solid, width: 0.80),
),
child: Padding(
padding: EdgeInsets.all(2.0),
child: Material(
shape:
RoundedRectangleBorder(borderRadius: BorderRadius.circular(10.0)),
elevation: 0.0,
child: ListTile(
title: DropdownButton(
items: _studynames.map((String dropdownitem) {
return DropdownMenuItem<String>(
value: dropdownitem,
child: Text(
dropdownitem,
style: TextStyle(color: Color(0xFF4BC1FF)),
),
);
}).toList(),
underline: Container(
height: 0,
),
value: _dropdownvalue,
onChanged: (valueSelected) {
setState(() {
debugPrint("$valueSelected value selected");
_dropdownvalue = valueSelected;
_DynamicWidgetState.dropdowndata[widget.index] = valueSelected;
});
},
),
),
),
),
)
),
SizedBox(width: 10),
Flexible(
flex: 1,
child: TextFormField(
controller: _descriptionController,
onChanged: (v) => _DynamicWidgetState.descriotiondata[widget.index] = v,
decoration: InputDecoration(
hintText: 'Study Description'
),
validator: (v){
if(v.trim().isEmpty) return 'Please enter Study Description';
return null;
},
),
)
],
);
throw UnimplementedError();
}
}
最佳答案
在“_DynamicFieldsState”下的字段中获取“下拉列表”值时，您没有使用创建的列表数据。因此，您的应用程序不知道它将在这些 Realm 中获得的值(value)。查看我是否刚刚更改了“_DynamicFieldsState”字段中的某些值。
import 'package:flutter/material.dart';
class DynamicWidgets extends StatefulWidget {
@override
_DynamicWidgetState createState() => _DynamicWidgetState();
}
class _DynamicWidgetState extends State<DynamicWidgets> {
final _formKey = GlobalKey<FormState>();
TextEditingController _nameController;
static List<String> dropdowndata=[null];
static List<String> descriotiondata=[null];
@override
void initState() {
// TODO: implement initState
super.initState();
_nameController = TextEditingController();
_nameController.text = "XR";
}
@override
void dispose() {
_nameController.dispose();
super.dispose();
}
@override
Widget build(BuildContext context) {
// TODO: implement build
return Scaffold(
resizeToAvoidBottomPadding: false,
body: Form(
key: _formKey,
child: Padding(
padding: const EdgeInsets.all(16.0),
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: [
Padding(
padding: const EdgeInsets.only(right: 32.0),
child: TextFormField(
controller: _nameController,
decoration: InputDecoration(hintText: 'Modality Name'),
validator: (v) {
if (v.trim().isEmpty) return 'Please enter something';
return null;
},
),
),
Text("Add More Study"),
SizedBox(
height: 5,
),
..._getFields(),
SizedBox(
height: 10,
),
FlatButton(
onPressed: () {
if (_formKey.currentState.validate()) {
_formKey.currentState.save();
debugPrint("Widget1 Key data: ${dropdowndata.toString()}");
debugPrint("Widget2 Key data: ${descriotiondata.toString()}");
}
},
child: Text(
'Submit',
style: TextStyle(color: Colors.white),
),
color: Colors.green,
),
],
),
),
),
);
throw UnimplementedError();
}
List<Widget> _getFields() {
List<Widget> friendsTextFields = [];
for (int i = 0; i < dropdowndata.length; i++) {
friendsTextFields.add(Padding(
padding: const EdgeInsets.symmetric(vertical: 16.0),
child: Row(
children: [
Expanded(child: DynamicFields(i)),
SizedBox(
width: 16,
),
// we need add button at last friends row
_addRemoveButton(true, i),
],
),
));
}
return friendsTextFields;
}
Widget _addRemoveButton(bool add, int index) {
print('index:' + index.toString());
return InkWell(
onTap: () {
if (add) {
// add new text-fields at the top of all friends textfields
dropdowndata.insert(0, null);
descriotiondata.insert(0, null);
} else {
dropdowndata.removeAt(index);
descriotiondata.removeAt(index);
}
setState(() {});
},
child: Container(
width: 30,
height: 30,
decoration: BoxDecoration(
color: (add) ? Colors.green : Colors.red,
borderRadius: BorderRadius.circular(20),
),
child: Icon(
(add) ? Icons.add : Icons.remove,
color: Colors.white,
),
),
);
}
}
class DynamicFields extends StatefulWidget {
final int index;
DynamicFields(this.index);
@override
_DynamicFieldsState createState() => _DynamicFieldsState();
}
class _DynamicFieldsState extends State<DynamicFields>{
TextEditingController _descriptionController;
var _selectedValue;
var _dropdownvalue;
String _myActivity;
String _myActivityResult;
static var _studynames = ["CT-62", "CT-53","CT-54","CT-50"];
@override
void initState() {
// TODO: implement initState
super.initState();
this._descriptionController=TextEditingController();
}
@override
void dispose() {
_descriptionController.dispose();
super.dispose();
}
@override
Widget build(BuildContext context) {
WidgetsBinding.instance.addPostFrameCallback((timeStamp) {
_descriptionController.text = _DynamicWidgetState.descriotiondata[widget.index] ?? '';
_selectedValue=_DynamicWidgetState.dropdowndata[widget.index] ?? '';
});
// TODO: implement build
return Row(
children: [
Flexible(
flex: 1,
child: Container(
margin: EdgeInsets.all(5.0),
decoration: BoxDecoration(
borderRadius: BorderRadius.circular(5.0),
border: Border.all(
color: Colors.blueGrey, style: BorderStyle.solid, width: 0.80),
),
child: Padding(
padding: EdgeInsets.all(2.0),
child: Material(
shape:
RoundedRectangleBorder(borderRadius: BorderRadius.circular(10.0)),
elevation: 0.0,
child: ListTile(
title: DropdownButton(
items: _studynames.map((String dropdownitem) {
return DropdownMenuItem<String>(
value: dropdownitem,
child: Text(
dropdownitem,
style: TextStyle(color: Color(0xFF4BC1FF)),
),
);
}).toList(),
underline: Container(
height: 0,
),
value: _DynamicWidgetState.dropdowndata[widget.index], // Here
onChanged: (valueSelected) {
setState(() {
debugPrint("$valueSelected value selected");
_dropdownvalue = _DynamicWidgetState.dropdowndata[widget.index]; // Here
_DynamicWidgetState.dropdowndata[widget.index] = valueSelected;
});
},
),
),
),
),
)
),
SizedBox(width: 10),
Flexible(
flex: 1,
child: TextFormField(
controller: _descriptionController,
onChanged: (v) => _DynamicWidgetState.descriotiondata[widget.index] = v,
decoration: InputDecoration(
hintText: 'Study Description'
),
validator: (v){
if(v.trim().isEmpty) return 'Please enter Study Description';
return null;
},
),
)
],
);
throw UnimplementedError();
}
}
关于flutter - Flutter动态DropdownFormField值未使用索引更新，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/64460254/