【发布时间】：2020-08-19 07:41:32
【问题描述】：
我从 JSON 填充状态名称并显示为下拉列表，之后我根据选择的第一个值显示第二个下拉列表。但是我现在不知道如何在第一个下拉列表值更改时填充第二个下拉列表。我还想在选择第二个下拉值时获取位置 ID、名称和城市。
我的杰森
{
"data": [
{
"state": "TEXAS",
"locations": [
{
"id": 1,
"name": "FITT Sugarland",
"city": "HOUSTON",
"state": "TEXAS",
"timezone": "",
"ownerName": "",
"ownerPhoneNumber": "",
"ownerEmail": "",
"ownerWebsite": "",
"capacity": 0,
"description": "HOUSTON SUGARLAND",
"createdBy": "",
"modifiedBy": "",
"createdAt": "2020-08-18T10:17:55.000Z",
"modifiedAt": "2020-08-18T10:17:55.000Z"
},
{
"id": 2,
"name": "FITT Pearland",
"city": "HOUSTON",
"state": "TEXAS",
"timezone": "",
"ownerName": "",
"ownerPhoneNumber": "",
"ownerEmail": "",
"ownerWebsite": "",
"capacity": 0,
"description": "second location",
"createdBy": "",
"modifiedBy": "",
"createdAt": "2020-08-18T10:18:38.000Z",
"modifiedAt": "2020-08-18T10:18:38.000Z"
}
]
}
]
}
模型类
class LocationModel {
List<LocationList> data;
LocationModel({this.data});
LocationModel.fromJson(Map<String, dynamic> json) {
if (json['data'] != null) {
data = new List<LocationList>();
json['data'].forEach((v) {
data.add(new LocationList.fromJson(v));
});
}
}
Map<String, dynamic> toJson() {
final Map<String, dynamic> data = new Map<String, dynamic>();
if (this.data != null) {
data['data'] = this.data.map((v) => v.toJson()).toList();
}
return data;
}
}
class LocationList {
String state;
List<Locations> locations;
LocationList({this.state, this.locations});
LocationList.fromJson(Map<String, dynamic> json) {
state = json['state'];
if (json['locations'] != null) {
locations = new List<Locations>();
json['locations'].forEach((v) {
locations.add(new Locations.fromJson(v));
});
}
}
Map<String, dynamic> toJson() {
final Map<String, dynamic> data = new Map<String, dynamic>();
data['state'] = this.state;
if (this.locations != null) {
data['locations'] = this.locations.map((v) => v.toJson()).toList();
}
return data;
}
}
class Locations {
int id;
String name;
String city;
String state;
String timezone;
String ownerName;
String ownerPhoneNumber;
String ownerEmail;
String ownerWebsite;
int capacity;
String description;
String createdBy;
String modifiedBy;
String createdAt;
String modifiedAt;
Locations(
{this.id,
this.name,
this.city,
this.state,
this.timezone,
this.ownerName,
this.ownerPhoneNumber,
this.ownerEmail,
this.ownerWebsite,
this.capacity,
this.description,
this.createdBy,
this.modifiedBy,
this.createdAt,
this.modifiedAt});
Locations.fromJson(Map<String, dynamic> json) {
id = json['id'];
name = json['name'];
city = json['city'];
state = json['state'];
timezone = json['timezone'];
ownerName = json['ownerName'];
ownerPhoneNumber = json['ownerPhoneNumber'];
ownerEmail = json['ownerEmail'];
ownerWebsite = json['ownerWebsite'];
capacity = json['capacity'];
description = json['description'];
createdBy = json['createdBy'];
modifiedBy = json['modifiedBy'];
createdAt = json['createdAt'];
modifiedAt = json['modifiedAt'];
}
Map<String, dynamic> toJson() {
final Map<String, dynamic> data = new Map<String, dynamic>();
data['id'] = this.id;
data['name'] = this.name;
data['city'] = this.city;
data['state'] = this.state;
data['timezone'] = this.timezone;
data['ownerName'] = this.ownerName;
data['ownerPhoneNumber'] = this.ownerPhoneNumber;
data['ownerEmail'] = this.ownerEmail;
data['ownerWebsite'] = this.ownerWebsite;
data['capacity'] = this.capacity;
data['description'] = this.description;
data['createdBy'] = this.createdBy;
data['modifiedBy'] = this.modifiedBy;
data['createdAt'] = this.createdAt;
data['modifiedAt'] = this.modifiedAt;
return data;
}
}
我的代码
import 'dart:io';
import 'package:fittheorem/models/location_list.dart';
import 'package:fittheorem/providers/auth_session.dart';
import 'package:fittheorem/providers/user_details.dart';
import 'package:fittheorem/ui/widgets/error_snakbar.dart';
import 'package:fittheorem/utils/app_config.dart';
import 'package:flutter/material.dart';
import 'package:flutter_svg/flutter_svg.dart';
import 'package:google_fonts/google_fonts.dart';
import 'package:provider/provider.dart';
class LocationUpdate extends StatefulWidget {
@override
_LocationUpdateState createState() => _LocationUpdateState();
}
class _LocationUpdateState extends State<LocationUpdate> {
LocationModel _locationModel;
bool isLoading = true;
String _selectedState = "TEXAS";
List<String> _statesList = [];
String _selectedLocation = "FITT Sugarland";
List<Locations> _locationsList = List();
@override
void initState() {
// TODO: implement initState
super.initState();
getList();
}
Future<void> getList() async {
try {
_locationModel = await Provider.of<UserDetails>(context, listen: false)
.getLocationList("token");
for (int i = 0; i < _locationModel.data.length; i++) {
_statesList.add(_locationModel.data[i].state);
}
_locationsList = _locationModel.data[0].locations;
_selectedState = _statesList[0];
_selectedLocation = _locationsList[0].name;
if (mounted) {
setState(() {
isLoading = false;
});
}
} on HttpException catch (error) {
CustomWidgets.buildErrorSnackbar(context);
} catch (error) {
CustomWidgets.buildErrorSnackbar(context);
}
}
@override
Widget build(BuildContext context) {
return Scaffold(
body: Container(
color: AppConfig.bgColor,
child: SafeArea(
child: Column(
children: <Widget>[
Container(
padding: EdgeInsets.fromLTRB(20.0, 10.0, 20.0, 10.0),
height: 40.0,
child: Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
crossAxisAlignment: CrossAxisAlignment.center,
children: <Widget>[
GestureDetector(
behavior: HitTestBehavior.translucent,
onTap: () {
Navigator.pop(context, true);
},
child: Container(
height: 25.0,
width: 25.0,
child: SvgPicture.asset(AppConfig.backImage,
color: Colors.white, semanticsLabel: 'back')),
),
Text('LOCATION',
style: GoogleFonts.roboto(
textStyle: TextStyle(
fontSize: 18.0, color: Color(0xffFFFFFF)),
)),
SizedBox(
width: 25.0,
),
],
),
),
Expanded(
child: Container(
color: Colors.white,
height: MediaQuery.of(context).size.height,
width: MediaQuery.of(context).size.width,
padding: EdgeInsets.all(30.0),
child: isLoading
? Center(
child: AppConfig().myLoader(),
)
: Column(
mainAxisAlignment: MainAxisAlignment.start,
crossAxisAlignment: CrossAxisAlignment.start,
children: [
SizedBox(
height: 20.0,
),
Padding(
padding: const EdgeInsets.only(left: 5.0),
child: Text('UPDATE YOUR LOCATION',
style: GoogleFonts.roboto(
textStyle: TextStyle(
fontSize: 16.0,
color: Color(0xff000000)),
)),
),
SizedBox(
height: 20.0,
),
Container(
height: 40.0,
decoration: new BoxDecoration(
border: new Border.all(
color: Colors.black54, width: 0.0),
borderRadius: new BorderRadius.circular(10.0),
),
child: new DropdownButtonHideUnderline(
child: ButtonTheme(
alignedDropdown: true,
child: new DropdownButton(
value: _selectedState,
hint: Text("State"),
isExpanded: true,
items: _statesList
.map((String item) =>
DropdownMenuItem<String>(
child: Text(item),
value: item))
.toList(),
onChanged: (String newValue) {
if (mounted)
setState(() {
_selectedState = newValue;
});
},
style: Theme.of(context)
.textTheme
.bodyText2,
))),
),
SizedBox(
height: 20.0,
),
Container(
height: 40.0,
decoration: new BoxDecoration(
border: new Border.all(
color: Colors.black54, width: 0.0),
borderRadius: new BorderRadius.circular(10.0),
),
child: new DropdownButtonHideUnderline(
child: ButtonTheme(
alignedDropdown: true,
child: new DropdownButton(
value: _selectedLocation,
hint: Text("Location"),
isExpanded: true,
items: _locationsList.map((item) {
return new DropdownMenuItem(
child: new Text(item.name),
value: item.name,
);
}).toList(),
onChanged: (newValue) {
if (mounted) print(newValue);
setState(() {
_selectedLocation = newValue;
});
},
style: Theme.of(context)
.textTheme
.bodyText2,
))),
)
],
),
),
)
],
),
),
),
);
}
}
【问题讨论】：
标签： flutter dart drop-down-menu