Question

我已经从json获取数据。现在，我必须将多个数据传递到下一个屏幕。我在列表视图中显示摘要，并能够将其发送到下一个屏幕。但是我在将说明，位置之类的多个数据发送到下一屏幕时遇到问题。

1）这是JSON数据。

List data = {
 "kind": "calendar#events",
 "etag": "\"p32gchndvjbiug0g\"",
 "updated": "2020-04-13T10:36:30.548Z",
 "timeZone": "Asia/Kolkata",
 "items": [
  {
   "kind": "calendar#event",
   "summary": "test event",
   "description": "test description",
   "location": "Maharashtra, India",
   "creator": {
    "email": "r******ar@gmail.com"
   },
   "start": {
    "dateTime": "2022-09-23T16:30:00+05:30"
   },
  },
{
   "kind": "calendar#event",
   "summary": "DEMO",
   "description": "Join Zoom Meeting\u003cbr\u003e",
   "location": "Nyati Eureka ( Commercial Complex), K",
   "creator": {
    "email": "k*********ar.rohit@gmail.com",
    "self": true
   },
   "start": {
    "dateTime": "2020-04-13T10:00:00+05:30"
   },
   }
 ]
} 

class Event {
  String kind;
  String etag;
  String summary;
  DateTime updated;
  String timeZone;
 List<Item> items;

  Event({
    this.kind,
    this.etag,
    this.summary,
    this.updated,
    this.timeZone,
    this.accessRole,
    this.items,
  });

  factory Event.fromJson(Map<String, dynamic> json) => Event(
        kind: json["kind"],
        etag: json["etag"],
        summary: json["summary"],
        updated: DateTime.parse(json["updated"]),
        timeZone: json["timeZone"],
       items: List<Item>.from(json["items"].map((x) => Item.fromJson(x))),
      );

  Map<String, dynamic> toJson() => {
        "kind": kind,
        "etag": etag,
        "summary": summary,
        "updated": updated.toIso8601String(),
        "timeZone": timeZone,
       "items": List<dynamic>.from(items.map((x) => x.toJson())),
      };
}

class Item {
  String kind;
  String summary;
  String description;
  String location;

  Item({
    this.kind,
    this.summary,
    this.description,
    this.location,
    });

  factory Item.fromJson(Map<String, dynamic> json) => Item(
        kind: json["kind"],
        summary: json["summary"],
        description: json["description"] == null ? null : json["description"],
        location: json["location"] == null ? null : json["location"],
       );

  Map<String, dynamic> toJson() => {
        "kind": kind,
       "summary": summary,
        "description": description == null ? null : description,
        "location": location == null ? null : location,
       };
}

2）JSON响应

  Future<Map<DateTime, List>> getTask() async {
    Map<DateTime, List> mapFetch = {};
    await Future.delayed(const Duration(seconds: 1), () {});
    String link =
        "LINK";
    var res = await http
        .get(Uri.encodeFull(link), headers: {"Accept": "application/json"});
      List data = jsonDecode(res.body)['items'];
       if (res.statusCode == 200) {
      Event event = eventFromJson(res.body);
       return mapFetch;
  }

 void _onDaySelected(DateTime day, List events) {
    setState(() {
      _selectedEvents = events;
    });
  }

3）第一个屏幕上的ListView

Widget _buildEventList() {
    return ListView(
     children: _selectedEvents
          .map(
            (event) => Card(
              shape: RoundedRectangleBorder(
                borderRadius: BorderRadius.circular(10.0),
              ),
              margin: EdgeInsets.symmetric(horizontal: 10.0, vertical: 4.0),
              color: Colors.white,
              child: ListTile(
                leading: Icon(
                  Icons.album,
                  color: Colors.blue,
                ),
                onTap: () =>
                   getItemAndNavigate(event, context),
                  title: Text(
                  event.toString(),
                ),
              ),
            ),
          )
          .toList(),
    );
  }
getItemAndNavigate(String _selectedEvents, BuildContext context) {
    Navigator.push(
        context,
        MaterialPageRoute(
            builder: (context) => EventDetail(itemHolder: _selectedEvents)));
  }

4）我需要将数据输入到下一个屏幕中，如何获取？

Answer 1

您可以在下面复制粘贴运行完整代码
步骤1：在getTask(中，您可以使用Future<Map<DateTime, List<Item>>> getTask()
步骤2：针对mapFetch[event.items[i].start.dateTime] = [event.items[i]];
步骤3：事件详细信息

class EventDetail extends StatefulWidget {
  List<Item> itemHolder;

  EventDetail({this.itemHolder});
  @override
  _EventDetailState createState() => _EventDetailState();
}

class _EventDetailState extends State<EventDetail> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: Text("Detail"),
        ),
        body: Text(
            ' ${widget.itemHolder[0].creator.email} ${widget.itemHolder[0].description}'));
  }
}

工作演示

完整代码

import 'package:flutter/material.dart';
import 'package:table_calendar/table_calendar.dart';
import 'package:http/http.dart' as http;
import 'dart:convert';

Event eventFromJson(String str) => Event.fromJson(json.decode(str));

String eventToJson(Event data) => json.encode(data.toJson());

class Event {
  String kind;
  String etag;
  DateTime updated;
  String timeZone;
  List<Item> items;

  Event({
    this.kind,
    this.etag,
    this.updated,
    this.timeZone,
    this.items,
  });

  factory Event.fromJson(Map<String, dynamic> json) => Event(
        kind: json["kind"],
        etag: json["etag"],
        updated: DateTime.parse(json["updated"]),
        timeZone: json["timeZone"],
        items: List<Item>.from(json["items"].map((x) => Item.fromJson(x))),
      );

  Map<String, dynamic> toJson() => {
        "kind": kind,
        "etag": etag,
        "updated": updated.toIso8601String(),
        "timeZone": timeZone,
        "items": List<dynamic>.from(items.map((x) => x.toJson())),
      };
}

class Item {
  String kind;
  String summary;
  String description;
  String location;
  Creator creator;
  Start start;

  Item({
    this.kind,
    this.summary,
    this.description,
    this.location,
    this.creator,
    this.start,
  });

  factory Item.fromJson(Map<String, dynamic> json) => Item(
        kind: json["kind"],
        summary: json["summary"],
        description: json["description"],
        location: json["location"],
        creator: Creator.fromJson(json["creator"]),
        start: Start.fromJson(json["start"]),
      );

  Map<String, dynamic> toJson() => {
        "kind": kind,
        "summary": summary,
        "description": description,
        "location": location,
        "creator": creator.toJson(),
        "start": start.toJson(),
      };
}

class Creator {
  String email;

  Creator({
    this.email,
  });

  factory Creator.fromJson(Map<String, dynamic> json) => Creator(
        email: json["email"],
      );

  Map<String, dynamic> toJson() => {
        "email": email,
      };
}

class Start {
  DateTime dateTime;

  Start({
    this.dateTime,
  });

  factory Start.fromJson(Map<String, dynamic> json) => Start(
        dateTime: DateTime.parse(json["dateTime"]),
      );

  Map<String, dynamic> toJson() => {
        "dateTime": dateTime.toIso8601String(),
      };
}

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> with TickerProviderStateMixin {
  List<Item> _selectedEvents;
  int _counter = 0;
  Map<DateTime, List<Item>> _events;
  CalendarController _calendarController;
  AnimationController _animationController;

  void _incrementCounter() {
    setState(() {
      _counter++;
    });
  }

  Future<Map<DateTime, List<Item>>> getTask() async {
    Map<DateTime, List<Item>> mapFetch = {};

    await Future.delayed(const Duration(seconds: 3), () {});

    /*String link = baseURL + fetchTodoByDate;
    var res = await http.post(Uri.encodeFull(link), headers: {"Accept": "application/json"});
    if (res.statusCode == 200) {
      // need help in creating fetch logic here
    }*/

    String responseString = '''
   {
 "kind": "calendar#events",
 "etag": "p32gchndvjbiug0g",
 "updated": "2020-04-13T10:36:30.548Z",
 "timeZone": "Asia/Kolkata",
 "items": [
  {
   "kind": "calendar#event",
   "summary": "test event",
   "description": "test description",
   "location": "Maharashtra, India",
   "creator": {
    "email": "r******ar@gmail.com"
   },
   "start": {
    "dateTime": "2022-09-23T16:30:00+05:30"
   }
  },
{
   "kind": "calendar#event",
   "summary": "DEMO",
   "description": "Join Zoom Meeting\u003cbr\u003e",
   "location": "Nyati Eureka ( Commercial Complex), K",
   "creator": {
    "email": "k*********ar.rohit@gmail.com",
    "self": true
   },
   "start": {
    "dateTime": "2020-04-13T10:00:00+05:30"
   }
   }
 ]
} 
    ''';

    Event event = eventFromJson(responseString);

    for (int i = 0; i < event.items.length; i++) {
      mapFetch[event.items[i].start.dateTime] = [event.items[i]];
    }

    return mapFetch;
  }

  void _onDaySelected(DateTime day, List events) {
    print('CALLBACK: _onDaySelected');
    setState(() {
      _selectedEvents = events;
    });
  }

  @override
  void initState() {
    final _selectedDay = DateTime.now();
    _selectedEvents = [];
    _calendarController = CalendarController();
    _animationController = AnimationController(
      vsync: this,
      duration: const Duration(milliseconds: 400),
    );

    _animationController.forward();
    WidgetsBinding.instance.addPostFrameCallback((_) {
      getTask().then((val) => setState(() {
            _events = val;
          }));
      //print( ' ${_events.toString()} ');
    });
    super.initState();
  }

  @override
  void dispose() {
    _calendarController.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            _buildTableCalendarWithBuilders(),
            const SizedBox(height: 8.0),
            const SizedBox(height: 8.0),
            Expanded(child: _buildEventList()),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: Icon(Icons.add),
      ),
    );
  }

  Widget _buildTableCalendarWithBuilders() {
    return TableCalendar(
      //locale: 'pl_PL',
      calendarController: _calendarController,
      events: _events,
      //holidays: _holidays,
      initialCalendarFormat: CalendarFormat.month,
      formatAnimation: FormatAnimation.slide,
      startingDayOfWeek: StartingDayOfWeek.sunday,
      availableGestures: AvailableGestures.all,
      availableCalendarFormats: const {
        CalendarFormat.month: '',
        CalendarFormat.week: '',
      },
      calendarStyle: CalendarStyle(
        outsideDaysVisible: false,
        weekendStyle: TextStyle().copyWith(color: Colors.blue[800]),
        holidayStyle: TextStyle().copyWith(color: Colors.blue[800]),
      ),
      daysOfWeekStyle: DaysOfWeekStyle(
        weekendStyle: TextStyle().copyWith(color: Colors.blue[600]),
      ),
      headerStyle: HeaderStyle(
        centerHeaderTitle: true,
        formatButtonVisible: false,
      ),
      builders: CalendarBuilders(
        selectedDayBuilder: (context, date, _) {
          return FadeTransition(
            opacity: Tween(begin: 0.0, end: 1.0).animate(_animationController),
            child: Container(
              margin: const EdgeInsets.all(4.0),
              padding: const EdgeInsets.only(top: 5.0, left: 6.0),
              color: Colors.deepOrange[300],
              width: 100,
              height: 100,
              child: Text(
                '${date.day}',
                style: TextStyle().copyWith(fontSize: 16.0),
              ),
            ),
          );
        },
        todayDayBuilder: (context, date, _) {
          return Container(
            margin: const EdgeInsets.all(4.0),
            padding: const EdgeInsets.only(top: 5.0, left: 6.0),
            color: Colors.amber[400],
            width: 100,
            height: 100,
            child: Text(
              '${date.day}',
              style: TextStyle().copyWith(fontSize: 16.0),
            ),
          );
        },
        markersBuilder: (context, date, events, holidays) {
          final children = <Widget>[];

          if (events.isNotEmpty) {
            children.add(
              Positioned(
                right: 1,
                bottom: 1,
                child: _buildEventsMarker(date, events),
              ),
            );
          }

          if (holidays.isNotEmpty) {
            children.add(
              Positioned(
                right: -2,
                top: -2,
                child: _buildHolidaysMarker(),
              ),
            );
          }

          return children;
        },
      ),
      onDaySelected: (date, events) {
        _onDaySelected(date, events);
        _animationController.forward(from: 0.0);
      },
      onVisibleDaysChanged: _onVisibleDaysChanged,
    );
  }

  void _onVisibleDaysChanged(
      DateTime first, DateTime last, CalendarFormat format) {
    print('CALLBACK: _onVisibleDaysChanged');
  }

  Widget _buildEventsMarker(DateTime date, List events) {
    return AnimatedContainer(
      duration: const Duration(milliseconds: 300),
      decoration: BoxDecoration(
        shape: BoxShape.rectangle,
        color: _calendarController.isSelected(date)
            ? Colors.brown[500]
            : _calendarController.isToday(date)
                ? Colors.brown[300]
                : Colors.blue[400],
      ),
      width: 16.0,
      height: 16.0,
      child: Center(
        child: Text(
          '${events.length}',
          style: TextStyle().copyWith(
            color: Colors.white,
            fontSize: 12.0,
          ),
        ),
      ),
    );
  }

  Widget _buildHolidaysMarker() {
    return Icon(
      Icons.add_box,
      size: 20.0,
      color: Colors.blueGrey[800],
    );
  }

  Widget _buildEventList() {
    return ListView(
      children: _selectedEvents
          .map((event) => Container(
                decoration: BoxDecoration(
                  border: Border.all(width: 0.8),
                  borderRadius: BorderRadius.circular(12.0),
                ),
                margin:
                    const EdgeInsets.symmetric(horizontal: 8.0, vertical: 4.0),
                child: ListTile(
                  title: Text(event.description),
                  onTap: () {
                    Navigator.push(
                        context,
                        MaterialPageRoute(
                            builder: (context) =>
                                EventDetail(itemHolder: _selectedEvents)));
                  },
                ),
              ))
          .toList(),
    );
  }
}

class EventDetail extends StatefulWidget {
  List<Item> itemHolder;

  EventDetail({this.itemHolder});
  @override
  _EventDetailState createState() => _EventDetailState();
}

class _EventDetailState extends State<EventDetail> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: Text("Detail"),
        ),
        body: Text(
            ' ${widget.itemHolder[0].creator.email} ${widget.itemHolder[0].description}'));
  }
}

Answer 2

请像下面这样编写您的下一个屏幕代码...

 import 'package:flutter/material.dart';

class NextWidget extends StatefulWidget {
  final String event;
  NextWidget({Key key, @required this.event}) : super(key: key);
  @override
  _NextWidgetState createState() => _NextWidgetState(event: event);
}

class _NextWidgetState extends State<NextWidget> {
  final String event;
  _NextWidgetState({Key key, @required this.event});
  @override
  Widget build(BuildContext context) {
    return Container();
  }
}

如何将从json提取的多个数据传递到下一个屏幕？

2 个答案: