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我得到了很大的幫助來構建這個動態的expansionTile，現在我試圖添加一個傳遞給onTap的類，以便它可以傳遞到另一個頁面。我嘗試了幾件事，並不斷收到此錯誤。如果我不向onTap添加任何內容，那麼函數會調用所有作品，但沒有數據可以傳遞。Flutter將類添加到由未來的構建器構建的小部件
任何指導都會很棒。
我得到這個錯誤：
I/flutter (15773): ══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════
I/flutter (15773): The following assertion was thrown building FutureBuilder(dirty; state:
I/flutter (15773): _FutureBuilderState#fe2cf()):
I/flutter (15773): setState() or markNeedsBuild() called during build.
I/flutter (15773): This Overlay widget cannot be marked as needing to build because the framework is already in the
I/flutter (15773): process of building widgets. A widget can be marked as needing to be built during the build phase
I/flutter (15773): only if one of its ancestors is currently building. This exception is allowed because the framework
I/flutter (15773): builds parent widgets before children, which means a dirty descendant will always be built.
I/flutter (15773): Otherwise, the framework might not visit this widget during this build phase.
I/flutter (15773): The widget on which setState() or markNeedsBuild() was called was:
I/flutter (15773): Overlay([LabeledGlobalKey<OverlayState>#5da5e]; state: OverlayState#12b2d(tracking 2 tickers;
I/flutter (15773): entries: [OverlayEntry#b3821(opaque: true; maintainState: false), OverlayEntry#b2a00(opaque:
I/flutter (15773): false; maintainState: true), OverlayEntry#a0c04(opaque: true; maintainState: false),
I/flutter (15773): OverlayEntry#11271(opaque: false; maintainState: true), OverlayEntry#54209(opaque: false;
I/flutter (15773): maintainState: false), OverlayEntry#1a91b(opaque: false; maintainState: true)]))
I/flutter (15773): The widget which was currently being built when the offending call was made was:
I/flutter (15773): FutureBuilder(dirty; state: _FutureBuilderState#fe2cf())
I/flutter (15773):
我想現在運行該代碼的環比JSON在ExpansionTile小工具下，我的元素添加到_onTap功能，並且還試圖只是建立該類並將類添加到_onTap並且錯誤仍在繼續。沒有它，它工作正常，但我需要在另一頁上的數據。任何想法都會很棒，我相信我錯過了一些愚蠢的事情，因爲我是新來的其他語言。
import 'dart:async';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:shared_preferences/shared_preferences.dart';
import 'package:http/http.dart' as http;
import 'package:cswauthapp/models.dart';
import 'package:cswauthapp/FacPage.dart';
import 'package:cswauthapp/ReasonPage.dart';
import 'dart:convert';
class SpecPage extends StatefulWidget {
SpecPage({Key key, this.spec}) : super(key: key);
final Specialties spec;
//final Facilities fac;
//static const String routeName = "/specs/spec";
@override
_SpecPageState createState() => new _SpecPageState();
}
class _SpecPageState extends State<SpecPage> {
Future<http.Response> _responseFuture;
bool _authenticated = false;
bool _dataReceived = false;
SharedPreferences prefs;
List myReasonlist;
int listcount = 0;
int specid;
@override
void initState() {
super.initState();
_responseFuture = http.get('http://174.138.61.246:8080/support/dc/${widget.spec.id}');
_getPrefs();
//_getSpecialty();
//_getFacilities();
}
_getPrefs() async {
prefs = await SharedPreferences.getInstance();
_authenticated = prefs.getBool('authenticated');
print('AUTH3: ' + _authenticated.toString());
print('AUTHCODE3: ' + prefs.getString('authcode'));
prefs.setInt('specid', widget.spec.id);
print('SPECID: ' + prefs.getInt('specid').toString());
specid = await prefs.getInt('specid');
_getReasons();
}
var jsonCodec = const JsonCodec();
_getReasons() async {
var _url = 'http://csw.abbadabba.tech:8080/support/getreferralreasons/$specid';
var http = createHttpClient();
var response = await http.get(_url);
var reasons = await jsonCodec.decode(response.body);
myReasonlist = await reasons.toList();
//_dataReceived = true;
if (mounted) {
setState(() {
_dataReceived = true;
listcount = myReasonlist.length;
});
}
}
Future<Null> _onRefresh() {
Completer<Null> completer = new Completer<Null>();
Timer timer = new Timer(new Duration(seconds: 3),() {
completer.complete();
});
return completer.future;
}
@override
Widget build(BuildContext context) {
var _children = <Widget>[
new Center(
child: new Container(
padding: new EdgeInsets.only(
left: 10.0, right: 10.0, top: 20.0, bottom: 10.0),
child: new Text('Referral Reasons for '+widget.spec.name,
style: new TextStyle(fontSize: 30.0),
textAlign: TextAlign.center,
),
),
),
new Expanded(
child: new FutureBuilder(
future: _responseFuture,
builder: (BuildContext context, AsyncSnapshot<http.Response> response) {
if (!response.hasData) {
return const Center(
child: const Text('Loading...'),
);
} else if (response.data.statusCode != 200) {
return const Center(
child: const Text('Error loading data'),
);
} else {
List<dynamic> json = JSON.decode(response.data.body);
return new MyExpansionTileList(json);
}
},
),
),
/*new Expanded(
flex: 1,
child: new RefreshIndicator(
child: new ListView.builder(
itemBuilder: _itemBuilder,
itemCount: listcount,
),
onRefresh: _onRefresh,
),
),*/
];
return new Scaffold(
appBar: new AppBar(title: new Text("My Specialty")),
body: new Column(
children: _children,
),
);
}
/*Widget _itemBuilder(BuildContext context, int index) {
Reasons reason = getReason(index);
return new ReasonWidget(reason: reason,);
}*/
Reasons getReason(int index) {
return new Reasons(
myReasonlist[index]['rid'],
myReasonlist[index]['reason'],
myReasonlist[index]['sid'],
myReasonlist[index]['specname']
);
//return new Specialties.fromMap(mylist[index]);
}
}
class MyExpansionTileList extends StatelessWidget {
final List<dynamic> elementList;
MyExpansionTileList(this.elementList);
List<Widget> _getChildren() {
List<Widget> children = [];
elementList.forEach((element) {
children.add(
new MyExpansionTile(element['did'], element['dname']),
);
});
return children;
}
@override
Widget build(BuildContext context) {
return new ListView(
children: _getChildren(),
);
}
}
class MyExpansionTile extends StatefulWidget {
final int did;
final String name;
MyExpansionTile(this.did, this.name);
@override
State createState() => new MyExpansionTileState();
}
class MyExpansionTileState extends State<MyExpansionTile> {
PageStorageKey _key;
Future<http.Response> _responseFuture;
List<Widget> reasonList;
List reasList;
//Reasons reason;
@override
void initState() {
super.initState();
_responseFuture =
http.get('http://174.138.61.246:8080/support/dcreasons/${widget.did}');
}
@override
Widget build(BuildContext context) {
_key = new PageStorageKey('${widget.did}');
return new ExpansionTile(
key: _key,
title: new Text(widget.name,
style: new TextStyle(fontWeight: FontWeight.bold),
),
children: <Widget>[
new FutureBuilder(
future: _responseFuture,
builder:
(BuildContext context, AsyncSnapshot<http.Response> response) {
if (!response.hasData) {
return const Center(
child: const Text('Loading...'),
);
} else if (response.data.statusCode != 200) {
return const Center(
child: const Text('Error loading data'),
);
} else {
List<dynamic> json = JSON.decode(response.data.body);
reasonList = [];
json.forEach((element) {
reasonList.add(new ListTile(
dense: true,
title: new Text(element['reason']),
onTap: _onTap(new Reasons(element['rid'], element['reason'], element['sid'], element['specname'])),
));
});
//reasList = json.toList();
return new Column(children: reasonList);
}
},
)
],
);
}
_onTap(Reasons reason) {
Route route = new MaterialPageRoute(
settings: new RouteSettings(name: "/reasons/reason"),
builder: (BuildContext context) => new ReasonPage(reason: reason),
);
Navigator.of(context).push(route);
}
}