我是 Flutter 世界和移动应用程序开发的新手，并且正在为如何在我的应用程序中传递数据而苦苦挣扎。这是我的代码，如何在同一页面上将数据从未来传递到另一个未来？这些是我的两个未来，我的班级和我的主页，请在未来建设者的帮助下。
这是我返回位置的未来。从她那里，我需要将位置 ID 传递给下一个未来。
Future<Location> Lastlocation() async {
final prefs = await SharedPreferences.getInstance();
final key = 'token';
final value = prefs.get(key) ?? 0;
String myUrl = "$serverUrl/location/getlastlocation?token=" + value;
http.Response response = await http.get(
myUrl,
headers: {
'Accept': 'application/json',
//'Authorization': 'token $value'
},
);
if (response.statusCode == 200) {
// If the server did return a 200 OK response,
return Location.fromJson(json.decode(response.body));
} else {
// then throw an exception.
throw Exception('Failed to load album');
}
}
**这是第二个未来，它返回取决于第一个未来的位置 ID 的天气列表 * Lastlocation()
Future<List> Getweither(String ID) async {
final prefs = await SharedPreferences.getInstance();
final key = 'token';
final value = prefs.get(key) ?? 0;
String myUrl = "$serverUrl/dashbaord/Getweither/$ID?token=" + value;
http.Response response = await http.get(myUrl,
headers: {
'Accept': 'application/json',
});
print("myUrldevice :"+myUrl);
print("status :"+response.statusCode.toString());
return json.decode(response.body);
}
这是我的课堂位置
// To parse this JSON data, do
//
// final location = locationFromJson(jsonString);
import 'dart:convert';
List<Location> locationFromJson(String str) => List<Location>.from(json.decode(str).map((x) => Location.fromJson(x)));
String locationToJson(List<Location> data) => json.encode(List<dynamic>.from(data.map((x) => x.toJson())));
class Location {
Location({
this.automaticIrrigation,
this.coordinates,
this.createdDate,
this.sensorIds,
this.id,
this.siteName,
this.description,
this.v,
});
bool automaticIrrigation;
List<double> coordinates;
DateTime createdDate;
List<String> sensorIds;
String id;
String siteName;
String description;
int v;
factory Location.fromJson(Map<String, dynamic> json) => Location(
automaticIrrigation: json["AutomaticIrrigation"],
coordinates: List<double>.from(json["Coordinates"].map((x) => x.toDouble())),
createdDate: DateTime.parse(json["Created_date"]),
sensorIds: List<String>.from(json["Sensor_ids"].map((x) => x)),
id: json["_id"],
siteName: json["SiteName"],
description: json["Description"],
v: json["__v"],
);
Map<String, dynamic> toJson() => {
"AutomaticIrrigation": automaticIrrigation,
"Coordinates": List<dynamic>.from(coordinates.map((x) => x)),
"Created_date": createdDate.toIso8601String(),
"Sensor_ids": List<dynamic>.from(sensorIds.map((x) => x)),
"_id": id,
"SiteName": siteName,
"Description": description,
"__v": v,
};
}
这是我的主页
import 'dart:convert';
import 'dart:developer';
import 'package:http/http.dart' as http;
import 'package:flutter/material.dart';
import 'package:fluttertoast/fluttertoast.dart';
import 'package:shared_preferences/shared_preferences.dart';
import 'package:sidebar_animation/Services/DataHelpers.dart';
import 'package:sidebar_animation/sidebar/sidebar_layout.dart';
import '../bloc.navigation_bloc/navigation_bloc.dart';
import 'package:sidebar_animation/constants.dart';
import 'package:flutter/gestures.dart';
import 'package:sidebar_animation/bloc.navigation_bloc/navigation_bloc.dart';
class HomePage extends StatelessWidget with NavigationStates {
@override
Widget build(BuildContext context) {
return MaterialApp(
debugShowCheckedModeBanner: false,
home: MyHomePage(),
);
}
}
class MyHomePage extends StatefulWidget {
@override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
DatabaseHelper2 databaseHelper2 = new DatabaseHelper2();
@override
void initState() {
super.initState();
}
@override
Widget build(BuildContext context) {
return Scaffold(
backgroundColor: Colors.grey[100],
body: ListView(
FutureBuilder(
future: databaseHelper2.Getweither(location_id),
builder: (context,snapshot) {
if (snapshot.hasError)
{
print(snapshot.error);
print("there is problem !");
}
return snapshot.hasData
? ItemList(list: snapshot.data)
: Center(child: CircularProgressIndicator(
),
);
}
),
);
}
Widget _buildProgrammCard() {
return Container(
height: 90,
child:
Card(
semanticContainer: true,
clipBehavior: Clip.antiAliasWithSaveLayer,
color: Colors.white,
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.circular(10.0),
),
elevation: 4,
margin: EdgeInsets.fromLTRB(14, 0, 14, 14),
child:
FutureBuilder(
future: databaseHelper2.Lastlocation(),
builder: (context,snapshot) {
if (snapshot.hasError)
{
print(snapshot.error);
print("mochkla lenaa *");
}
return snapshot.hasData
? Text("Location :" +snapshot.data.siteName)
: Center(child: CircularProgressIndicator(
),
);
}
),
),
);
}
class ItemList extends StatelessWidget{
List list;
ItemList({this.list});
ScrollController _controller = new ScrollController();
@override
Widget build(BuildContext context) {
return ListView.builder(
itemCount: list == null ? 0 : list.length,
scrollDirection: Axis.horizontal,
itemExtent: 190.0,
itemBuilder: (context, index) {
return Padding(
padding: const EdgeInsets.fromLTRB(10, 0, 0, 14),
child: Container(
decoration: BoxDecoration(
image: DecorationImage(
image: NetworkImage(
item.storyUrl,
),
fit: BoxFit.cover,
colorFilter: ColorFilter.mode(
Colors.black26,
BlendMode.darken,
),
),
borderRadius: BorderRadius.circular(10.0),
color: Colors.grey,
),
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: <Widget>[
Padding(
padding: const EdgeInsets.all(10.0),
child: Text(
"temp :",
style: TextStyle(color: Colors.white),
),
),
Padding(
padding: EdgeInsets.only(left: 24),
child:
Text(
list[i]['Weither']['Temp'],
),
),
],
),
),
);
},
),
}
}
最后，我需要从第一个 future 中获取 location id，它将 Location 返回到第二个 future Getweither(String ID)以获取指定位置的天气。