我正在寻找有关早期问题的扩展帮助,该问题向我展示了一种访问json数据的方法MovementDataSource
。在这种情况下,第一页会使用listview和向用户显示一系列运动getMovements()
。选择动作后,第2页上的用户会通过列表视图和看到变化列表getVariationsByMovement()
。然后,在选择变体之后,向用户显示第3页,该页面使我可以访问单数形式的所有项目VariationModel
。(现在这只是variationName)
我还有另一个用例,我在应用程序的另一部分,但需要绕过上面第1页和第2页的用户工作流程直接跳转到第3页。那时我可以访问String Movement
和String VariationName
。我正在寻找帮助-一个函数示例,我可以传递这两个变量,然后给我一个VariationName
对象,以直接将链接传递给第3页的构造函数。在MovementDataSource
下面,getVariation()
我希望有一个函数帮助。
class MovementDataSource extends ChangeNotifier{
List<Map> getAll() => _movement;
List<String> getMovements()=> _movement
.map((map) => MovementModel.fromJson(map))
.map((item) => item.movement)
.toList();
getVariationsByMovement(String movement) => _movement
.map((map) => MovementModel.fromJson(map))
.where((item) => item.movement == movement)
.map((item) => item.variation)
.expand((i) => i)
.toList();
VariationModel getVariation(String movement, String variation){
**Return VariationModel from List _movement json**
}
List _movement = [
{
"movement": "Plank",
"alias": "plank",
"variation": [
{"variationName": "High Plank"}, {"variationName": "Forearm Plank"},
]
},
{
"movement": "Side Plank",
"alias": "side plank",
"variation": [
{"variationName": "Side Plank Right"}, {"variationName": "Side Plank Left"},
],
},
];
}
class MovementModel {
MovementModel({
this.movement,
this.alias,
this.variation,
});
String movement;
String alias;
List<VariationModel> variation;
factory MovementModel.fromJson(Map<String, dynamic> json) => MovementModel(
movement: json["movement"],
alias: json["alias"],
variation: List<VariationModel>.from(
json["variation"].map((x) => VariationModel.fromJson(x))),
);
Map<String, dynamic> toJson() => {
"movement": movement,
"alias": alias,
"variation": List<dynamic>.from(variation.map((x) => x.toJson())),
};
}
class VariationModel {
VariationModel({
this.variationName,
});
String variationName;
factory VariationModel.fromJson(Map<String, dynamic> json) => VariationModel(
variationName: json["variationName"],
);
Map<String, dynamic> toJson() => {
"variationName": variationName,
};
}
上面第3页的示例-此用例中的直接目标。
class TargetPage extends StatelessWidget {
final VariationModel variation;
SelectDefaultItemPage({this.variation});
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text("test"),
),
body: Text(variation.variationName));
}
}
源页面的示例,其中包含指向上述第3页目标的直接链接。这就是getVariation()
调用该函数并将VariationModel传递到上面的SourcePage的地方。
class SourcePage extends StatelessWidget {
final VariationModel variation;
SelectDefaultItemPage({this.variation});
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text("test"),
),
body:FlatButton(
child: Text(
"Go to TargetPage",
),
onPressed: () async {Navigator.push(context, MaterialPageRoute(
builder: (_) => SourcePage(getVariation(movement: movement, variation:
variation)));
},
)
}
}
谢谢你的帮助。
您可以复制粘贴运行完整的代码下面
你可以传递movementDataSource
,movement
并variation
以SourcePage
而在SourcePage
通话
TargetPage(variation: movementDataSource.getVariation(
movement: movement,
variation: variation.variationName))
程式码片段
VariationModel getVariation({String movement, String variation}) => _movement
.map((map) => MovementModel.fromJson(map))
.where((item) => item.movement == movement)
.map((item) => item.variation)
.expand((i) => i)
.where((e) => e.variationName == variation)
.first;
...
onTap: () async {
Navigator.push(
context,
MaterialPageRoute(
builder: (_) => SourcePage(
movementDataSource: _movementDataSource,
movement: movement,
variation: vList[index])));
},
...
class SourcePage extends StatelessWidget {
final MovementDataSource movementDataSource;
final String movement;
final VariationModel variation;
SourcePage({this.movementDataSource, this.movement, this.variation});
@override
Widget build(BuildContext context) {
return Scaffold(
...
onPressed: () async {
Navigator.push(
context,
MaterialPageRoute(
builder: (_) => TargetPage(
variation: movementDataSource.getVariation(
movement: movement,
variation: variation.variationName))));
},
));
...
class TargetPage extends StatelessWidget {
final VariationModel variation;
TargetPage({this.variation});
工作演示
完整的代码
import 'package:flutter/material.dart';
import 'dart:convert';
List<MovementModel> movementModelFromJson(String str) =>
List<MovementModel>.from(
json.decode(str).map((x) => MovementModel.fromJson(x)));
String movementModelToJson(List<MovementModel> data) =>
json.encode(List<dynamic>.from(data.map((x) => x.toJson())));
class MovementDataSource extends ChangeNotifier {
List<Map> getAll() => _movement;
List<String> getMovements() => _movement
.map((map) => MovementModel.fromJson(map))
.map((item) => item.movement)
.toList();
// I'd like this to return a list of movement.variation.variationName
getVariationsByMovement(String movement) => _movement
.map((map) => MovementModel.fromJson(map))
.where((item) => item.movement == movement)
.map((item) => item.variation)
.expand((i) => i)
.toList();
VariationModel getVariation({String movement, String variation}) => _movement
.map((map) => MovementModel.fromJson(map))
.where((item) => item.movement == movement)
.map((item) => item.variation)
.expand((i) => i)
.where((e) => e.variationName == variation)
.first;
List _movement = [
{
"movement": "Plank",
"alias": "plank",
"variation": [
{"variationName": "High Plank"},
{"variationName": "Forearm Plank"},
]
},
{
"movement": "Side Plank",
"alias": "side plank",
"variation": [
{"variationName": "Side Plank Right"},
{"variationName": "Side Plank Left"},
],
},
];
}
class MovementModel {
MovementModel({
this.movement,
this.alias,
this.variation,
});
String movement;
String alias;
List<VariationModel> variation;
factory MovementModel.fromJson(Map<String, dynamic> json) => MovementModel(
movement: json["movement"],
alias: json["alias"],
variation: List<VariationModel>.from(
json["variation"].map((x) => VariationModel.fromJson(x))),
);
Map<String, dynamic> toJson() => {
"movement": movement,
"alias": alias,
"variation": List<dynamic>.from(variation.map((x) => x.toJson())),
};
}
class VariationModel {
VariationModel({
this.variationName,
});
String variationName;
factory VariationModel.fromJson(Map<String, dynamic> json) => VariationModel(
variationName: json["variationName"],
);
Map<String, dynamic> toJson() => {
"variationName": variationName,
};
}
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
visualDensity: VisualDensity.adaptivePlatformDensity,
),
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;
String movement = "Plank";
MovementDataSource _movementDataSource = MovementDataSource();
void _incrementCounter() {
List<VariationModel> vList =
_movementDataSource.getVariationsByMovement("Plank");
for (int i = 0; i < vList.length; i++) {
print(vList[i].variationName);
}
setState(() {
_counter++;
});
}
@override
Widget build(BuildContext context) {
List<VariationModel> vList =
_movementDataSource.getVariationsByMovement(movement);
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: ListView.builder(
scrollDirection: Axis.vertical,
shrinkWrap: true,
itemCount: vList.length,
itemBuilder: (buildContext, index) {
return Card(
child: ListTile(
title: Text(
vList[index].variationName.toString(),
style: TextStyle(fontSize: 20),
),
trailing: Icon(Icons.keyboard_arrow_right),
onTap: () async {
Navigator.push(
context,
MaterialPageRoute(
builder: (_) => SourcePage(
movementDataSource: _movementDataSource,
movement: movement,
variation: vList[index])));
},
),
);
}),
floatingActionButton: FloatingActionButton(
onPressed: _incrementCounter,
tooltip: 'Increment',
child: Icon(Icons.add),
),
);
}
}
class SourcePage extends StatelessWidget {
final MovementDataSource movementDataSource;
final String movement;
final VariationModel variation;
SourcePage({this.movementDataSource, this.movement, this.variation});
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text("Source page"),
),
body: FlatButton(
child: Text(
"Go to TargetPage",
),
onPressed: () async {
Navigator.push(
context,
MaterialPageRoute(
builder: (_) => TargetPage(
variation: movementDataSource.getVariation(
movement: movement,
variation: variation.variationName))));
},
));
}
}
class TargetPage extends StatelessWidget {
final VariationModel variation;
TargetPage({this.variation});
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text("Target page"),
),
body: Text(variation.variationName));
}
}
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