类 'List<Event>' 在颤振应用程序中没有实例获取器'docs'

Question

我正在使用表日历小部件构建一个约会日程安排页面。我可以为firebase集合/文档写预约。现在，我需要从集合中提取约会，并将其显示为日历下方的列表。

我在另一个页面上使用了这个代码，实际上我从那里复制了if，并在这里使用它。代码在另一页上有效，但我在这里得到了错误。这两页的差异很小，但并不太大。导致此错误的原因是什么？

这是日历页的代码。

// Example holidays
final Map<DateTime, List> _holidays = {
DateTime(2020, 1, 1): ['New Year's Day'],
DateTime(2020, 1, 6): ['Epiphany'],
DateTime(2020, 2, 14): ['Valentine's Day'],
DateTime(2020, 4, 21): ['Easter Sunday'],
DateTime(2020, 4, 22): ['Easter Monday'],
};
final eventsRef = FirebaseFirestore.instance.collection('agency').doc(globals.agencyId).collection('event');
bool showSpinner = false;
class AppointmentCalendarScreen extends StatefulWidget {
AppointmentCalendarScreen({Key key, this.title}) : super(key: key);
final String title;
@override
_AppointmentCalendarScreenState createState() => _AppointmentCalendarScreenState();
}
class _AppointmentCalendarScreenState extends State<AppointmentCalendarScreen> with TickerProviderStateMixin {
Map<DateTime, List> _events;
List _selectedEvents;
AnimationController _animationController;
CalendarController _calendarController;
// =================================================================
@override
void initState() {
super.initState();
final _selectedDay = DateTime.now();
_events = {
_selectedDay.subtract(Duration(days: 30)): [
'Event A0',
'Event B0',
'Event C0'
],
_selectedDay.subtract(Duration(days: 27)): ['Event A1'],
_selectedDay.subtract(Duration(days: 20)): [
'Event A2',
'Event B2',
'Event C2',
'Event D2'
],
_selectedDay.subtract(Duration(days: 16)): ['Event A3', 'Event B3'],
_selectedDay.subtract(Duration(days: 10)): [
'Event A4',
'Event B4',
'Event C4'
],
_selectedDay.subtract(Duration(days: 4)): [
'Event A5',
'Event B5',
'Event C5'
],
_selectedDay.subtract(Duration(days: 2)): ['Event A6', 'Event B6'],
_selectedDay: ['Event A7', 'Event B7', 'Event C7', 'Event D7'],
_selectedDay.add(Duration(days: 1)): [
'Event A8',
'Event B8',
'Event C8',
'Event D8'
],
_selectedDay.add(Duration(days: 3)):
Set.from(['Event A9', 'Event A9', 'Event B9']).toList(),
_selectedDay.add(Duration(days: 7)): [
'Event A10',
'Event B10',
'Event C10'
],
_selectedDay.add(Duration(days: 11)): ['Event A11', 'Event B11'],
_selectedDay.add(Duration(days: 17)): [
'Event A12',
'Event B12',
'Event C12',
'Event D12'
],
_selectedDay.add(Duration(days: 22)): ['Event A13', 'Event B13'],
_selectedDay.add(Duration(days: 26)): [
'Event A14',
'Event B14',
'Event C14'
],
};
_calendarController = CalendarController();
_animationController = AnimationController(
vsync: this,
duration: const Duration(milliseconds: 400),
);
_animationController.forward();
}
@override
void dispose() {
_animationController.dispose();
_calendarController.dispose();
super.dispose();
}
void _onDaySelected(DateTime day, List events, List holidays) {
print('CALLBACK: _onDaySelected');
setState(() {
_selectedEvents = events;
});
}
void _onVisibleDaysChanged(
DateTime first, DateTime last, CalendarFormat format) {
print('CALLBACK: _onVisibleDaysChanged');
}
void _onCalendarCreated(
DateTime first, DateTime last, CalendarFormat format) {
print('CALLBACK: _onCalendarCreated');
}
@override
Widget build(BuildContext context) {
final eventProvider = Provider.of<EventProvider>(context);
return Scaffold(
appBar: AppBar(
automaticallyImplyLeading: false,
title: Row(
mainAxisAlignment: MainAxisAlignment.center,
children: [
Image.asset('assets/images/Appbar_logo.png',
fit: BoxFit.cover, height: 56),
],
),
),
backgroundColor: Colors.white,
resizeToAvoidBottomInset: false,
body: Column(
mainAxisSize: MainAxisSize.max,
children: <Widget>[
_buildTableCalendar(),
const SizedBox(height: 8.0),
ElevatedButton(
onPressed: () async {
setState(() {
showSpinner = true;
});
try {
globals.newAgency = true;
Navigator.of(context).pushReplacement(MaterialPageRoute(
builder: (context) => AddEventScreen()));
setState(() {
showSpinner = false;
});
} catch (e) {
// todo: add better error handling
print(e);
}
},
child: Text('Add Event'),
),
const SizedBox(height: 8.0),
Expanded(child: _buildEventList()),
],
),
);
}
// Simple TableCalendar configuration (using Styles)
Widget _buildTableCalendar() {
return TableCalendar(
calendarController: _calendarController,
events: _events,
holidays: _holidays,
startingDayOfWeek: StartingDayOfWeek.sunday,
calendarStyle: CalendarStyle(
selectedColor: Colors.deepOrange[400],
todayColor: Colors.deepOrange[200],
markersColor: Colors.deepPurpleAccent,
outsideDaysVisible: false,
),
headerStyle: HeaderStyle(
formatButtonTextStyle:
TextStyle().copyWith(color: Colors.white, fontSize: 15.0),
formatButtonDecoration: BoxDecoration(
color: Colors.deepOrange[400],
borderRadius: BorderRadius.circular(16.0),
),
),
onDaySelected: _onDaySelected,
onVisibleDaysChanged: _onVisibleDaysChanged,
onCalendarCreated: _onCalendarCreated,
);
}
Widget _buildHolidaysMarker() {
return Icon(
Icons.add_box,
size: 20.0,
color: Colors.blueGrey[800],
);
}
Widget _buildEventList() {
return Container(
child: StreamBuilder(
stream: FirestoreService().getEvent(),
builder: (context, snapshot) {
if (!snapshot.hasData)
return Center(
child: const Text(
'Loading...',
style: TextStyle(
fontSize: 20, fontWeight: FontWeight.bold),
));
return new ListView.builder(
itemCount: snapshot.data.docs.length,
itemBuilder: (BuildContext context, int index) {
Event _event = Event.fromFirestore(
snapshot.data.docs[index].data());
return ListTile(
isThreeLine: true,
title: Text(
'Event: ${_event.eventName ?? 'n/a'}',
style: TextStyle(
fontWeight: FontWeight.w900,
color: Colors.blueAccent),
),
subtitle: Text.rich(TextSpan(
text:
'${_event.eventName ?? 'n/a'}, ${_event
.eventStartTime ?? 'n/a'}, ${_event
.eventDuration ?? 'n/a'}',
children: <TextSpan>[
TextSpan(
text:
'n${_event.eventDescription ?? 'n/a'}',
style: TextStyle(
fontWeight: FontWeight.w900,
color: Colors.blueGrey),
)
])),
onTap: () {
globals.newTrxn = false;
Navigator.of(context).push(MaterialPageRoute(
builder: (context) =>
AddEventScreen(
snapshot.data.docs[index])));
},
);
}

);
},
),
);
}
}

这是我得到的错误：

======== Exception caught by widgets library =======================================================
The following NoSuchMethodError was thrown building StreamBuilder<List<Event>>(dirty, state: _StreamBuilderBaseState<List<Event>, AsyncSnapshot<List<Event>>>#49aa8):
Class 'List<Event>' has no instance getter 'docs'.
Receiver: Instance(length:0) of '_GrowableList'
Tried calling: docs

这是提供商代码：

class EventProvider with ChangeNotifier {
final firestoreService = FirestoreService();
FirebaseFirestore _db = FirebaseFirestore.instance;
//final eventRef = FirebaseFirestore.instance.collection(('events'));
String _eventName;
TimeOfDay _eventStartTime;
String _eventDuration;
DateTime _eventDate;
String _eventDescription;
String _agentId;
String _agencyId;
//Getters
String get eventName => _eventName;
TimeOfDay get eventStartTime => _eventStartTime;
String get eventDuration => _eventDuration;
DateTime get eventDate => _eventDate;
String get eventDescription => _eventDescription;
//Setters
changeeventname(String value) {
_eventName = value;
notifyListeners();
}
changeeventstarttime(TimeOfDay value) {
_eventStartTime = value;
notifyListeners();
}
changeeventduration(String value) {
_eventDuration = value;
notifyListeners();
}
changeeventdate(DateTime value) {
_eventDate = value;
notifyListeners();
}
changeeventdescription(String value) {
_eventDescription = value;
notifyListeners();
}
loadValues(Event event) {
_eventName = event.eventName;
_eventStartTime = event.eventStartTime;
_eventDuration = event.eventDuration;
_eventDate = event.eventDate;
_eventDescription = event.eventDescription;
}
saveEvent() {
var newEvent = Event(
eventName: _eventName,
eventStartTime: _eventStartTime,
eventDuration: _eventDuration,
eventDate: _eventDate,
eventDescription: _eventDescription,
agencyId: globals.agencyId,
agentId: globals.currentAgentId);

// If the agency is a new agency retrieve the agency
// document ID and save it to a new agent document
if (globals.newEvent == true) {
String id = _db.collection('event').doc().id;
firestoreService.saveEvent(newEvent);
globals.newEvent = false;
} else {
firestoreService.saveEvent(newEvent);
}
}
}

Answer 1

ListView.builder的itemCount属性导致错误。

CCD_ 3应该是CCD_。

这是因为Stream发出的数据类型是List<Event>。标准List类没有名为docs的方法，因此当ListView.builder尝试访问长度属性时，它会抛出NoSuchMethodError

当为列表中的任何项目调用onTap处理程序时，也会发生同样的错误，因为它也在引用snapshot.data.docs