flutter - 如何根据flutter中的下拉选择显示json数据?
问题描述
我正在创建具有下拉和列表视图的页面。现在我在列表视图中显示完整数据。如果我想要任何特定的日期数据,那么我需要做什么。请帮我解决这个问题。下面是我正在获取的 JSON。
{ “数据”: [{ "日期": "2019-07-08", “细节”: [{ “身份证”:1 }, { “身份证”:2 }] }, { “日期”:“2019-07-09”, “细节”: [{ “身份证”:3 }, { “身份证”:4 }] }, { “日期”:“2019-07-10”, “细节”: [{ “身份证”:5 }, { “身份证”:6 }] } ] }
下面是代码
未来的 getData() 异步 { var response = 等待 http.get( Uri.encodeFull(url), 标题:{ “接受”:“应用程序/json” } ); 设置状态((){ var extractdata = jsonDecode(response.body); 数据=提取数据[“数据”]; }); 返回“成功”; } 柱子( 孩子们: [ 展开( 孩子:容器( 颜色:Colors.greenAccent, 孩子:ListView.builder( 项目计数:数据 == 空?0:数据长度, 收缩包装:是的, itemBuilder:(上下文,索引){ 返回 ListView.builder( 收缩包装:是的, 物理:NeverScrollableScrollPhysics(), 项目计数:数据 == 空?0 : 数据[索引]["Session_Details"].length, itemBuilder: (context, i) { 返回 ListTile(title: Text("id")); } ); } ), ) ), ] )
解决方案
您可以在下面复制粘贴运行完整代码
您可以比较选定的下拉值并仅显示特定数据
并返回Container()
(不显示)其他
代码片段
ListView.builder(
itemCount: payload == null ? 0 : payload.data.length,
shrinkWrap: true,
itemBuilder: (context, index) {
return ListView.builder(
shrinkWrap: true,
physics: NeverScrollableScrollPhysics(),
itemCount: payload == null
? 0
: payload.data[index].details.length,
itemBuilder: (context, i) {
if (dropdownValue == null) {
return ListTile(
title: Text(
"${payload.data[index].details[i].id}"));
} else {
if (payload.data[index] == dropdownValue) {
return ListTile(
title: Text(
"${payload.data[index].details[i].id}"));
} else {
return Container();
}
}
});
}),
工作演示
完整代码
import 'package:flutter/material.dart';
import 'package:http/http.dart' as http;
// To parse this JSON data, do
//
// final payload = payloadFromJson(jsonString);
import 'dart:convert';
Payload payloadFromJson(String str) => Payload.fromJson(json.decode(str));
String payloadToJson(Payload data) => json.encode(data.toJson());
class Payload {
List<Datum> data;
Payload({
this.data,
});
factory Payload.fromJson(Map<String, dynamic> json) => Payload(
data: List<Datum>.from(json["data"].map((x) => Datum.fromJson(x))),
);
Map<String, dynamic> toJson() => {
"data": List<dynamic>.from(data.map((x) => x.toJson())),
};
}
class Datum {
DateTime date;
List<Detail> details;
Datum({
this.date,
this.details,
});
factory Datum.fromJson(Map<String, dynamic> json) => Datum(
date: DateTime.parse(json["Date"]),
details:
List<Detail>.from(json["Details"].map((x) => Detail.fromJson(x))),
);
Map<String, dynamic> toJson() => {
"Date":
"${date.year.toString().padLeft(4, '0')}-${date.month.toString().padLeft(2, '0')}-${date.day.toString().padLeft(2, '0')}",
"Details": List<dynamic>.from(details.map((x) => x.toJson())),
};
}
class Detail {
int id;
Detail({
this.id,
});
factory Detail.fromJson(Map<String, dynamic> json) => Detail(
id: json["id"],
);
Map<String, dynamic> toJson() => {
"id": id,
};
}
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
final String title;
@override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
int _counter = 0;
Payload payload;
Datum dropdownValue = null;
Future getData() async {
var response = await http
.get("https://www.json-generator.com/api/json/get/bOpGzigKOG?indent=2");
payload = payloadFromJson(response.body);
setState(() {});
return 'success';
}
void _incrementCounter() {
setState(() {
_counter++;
});
}
@override
void initState() {
WidgetsBinding.instance.addPostFrameCallback((_) {
getData();
});
super.initState();
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: payload == null
? CircularProgressIndicator()
: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Center(
child: DropdownButton<Datum>(
//isDense: true,
hint: Text('Choose'),
value: dropdownValue,
icon: Icon(Icons.check_circle_outline),
iconSize: 24,
elevation: 16,
style: TextStyle(color: Colors.deepPurple),
underline: Container(
height: 2,
color: Colors.blue[300],
),
onChanged: (Datum newValue) {
setState(() {
dropdownValue = newValue;
});
},
items: payload.data
.map<DropdownMenuItem<Datum>>((Datum value) {
return DropdownMenuItem<Datum>(
value: value,
child: Text(
' ${value.date.year.toString()}/${value.date.month.toString()}/${value.date.day.toString()}'));
}).toList(),
),
),
ListView.builder(
itemCount: payload == null ? 0 : payload.data.length,
shrinkWrap: true,
itemBuilder: (context, index) {
return ListView.builder(
shrinkWrap: true,
physics: NeverScrollableScrollPhysics(),
itemCount: payload == null
? 0
: payload.data[index].details.length,
itemBuilder: (context, i) {
if (dropdownValue == null) {
return ListTile(
title: Text(
"${payload.data[index].details[i].id}"));
} else {
if (payload.data[index] == dropdownValue) {
return ListTile(
title: Text(
"${payload.data[index].details[i].id}"));
} else {
return Container();
}
}
});
}),
Text(
'You have pushed the button this many times:',
),
Text(
'$_counter',
style: Theme.of(context).textTheme.headline4,
),
],
),
),
floatingActionButton: FloatingActionButton(
onPressed: _incrementCounter,
tooltip: 'Increment',
child: Icon(Icons.add),
),
);
}
}
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