我实现了两个下拉菜单。当我选择州和地区时,它工作正常。当我更改状态时,它显示我一个错误。在getDistricts()方法中将区域下拉列表值设置为null。请帮助并提前致谢。
在控制台中收到此错误:
应该只有一个项目具有[DropdownButton]的值:1。检测到零或2个或更多[DropdownMenuItem]相同值'package:flutter / src / material / dropdown.dart':失败断言:828行pos 15:'items == null || items.isEmpty ||值==空|| items.where(((DropdownMenuItem item){返回item.value==值; })。length == 1'
class AddAddress extends StatelessWidget {
@override
Widget build(BuildContext context) {
return AddAddressPage();
}
}
class AddAddressPage extends StatefulWidget {
@override
_AddAddressPageState createState() => _AddAddressPageState();
}
class _AddAddressPageState extends State<AddAddressPage> {
bool loader = false;
int intState;
int intDistrict;
List<Location> districts=listDistricts;
List<Location> states=listStates;
getDistricts()async{
setState(() {
loader=false;
});
List<Location> district= await service.getDistrictsByStateId(intState);
setState(() {
districts=district;
loader=false;
});
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text("Address"),
backgroundColor: Colors.white,
centerTitle: true,
),
body: Stack(
children: <Widget>[
SingleChildScrollView(
child: Padding(
padding: const EdgeInsets.only(top: 10.0, left: 30, right: 30),
child: Form(
child: Container(
child: Column(
children: <Widget>[
Padding(
padding: const EdgeInsets.only(top: 15.0),
child: DropdownButtonFormField<int>(
decoration: InputDecoration(
contentPadding:
const EdgeInsets.only(left: 30, right: 10),
border: OutlineInputBorder(
borderRadius:
BorderRadius.all(Radius.circular(15))),
),
hint: Text('state'),
value: intState,
items: states.map((location) {
return new DropdownMenuItem<int>(
child: Text(location.name),
value: location.id,
);
}).toList(),
onChanged: (int value) {
setState(() {
intState = value;
intDistrict=null;
getDistricts();
});
}),
),
Padding(
padding: const EdgeInsets.only(top: 15.0),
child: DropdownButtonFormField<int>(
decoration: InputDecoration(
contentPadding:
const EdgeInsets.only(left: 30, right: 10),
border: OutlineInputBorder(
borderRadius:
BorderRadius.all(Radius.circular(15))),
),
hint: Text(' district'),
value: intDistrict,
items: districts.map((location) {
return new DropdownMenuItem<int>(
child: Text(location.name),
value: location.id,
);
}).toList(),
onChanged: (int value) {
intDistrict = value;
}),
),
],
),
),
),
),
),
ProgressLoader(
loader: loader,
)
],
),
);
}
}
[我认为问题在于,当您选择新状态时,您只是将inDiDistrict值设置为null,而District下拉列表具有dropdownitems,因此我认为如果您在将intDistrict设置为null之前清除了分区,则它应该可以工作。
onChanged: (int value) {
setState(() {
intState = value;
districts.clear(); // added line
intDistrict=null;
getDistricts();
});
}),
感谢您的帮助。我发现了问题。由于我在dropdown.dart文件中升级了flutter SDK(而不是稳定的SDK),因此与以前的版本有所不同。因此,我与稳定的SDK进行了比较并修改了文件。感谢您的时间和帮助。