我试图获取总价。我的情况是这样的：
在这种情况下，我涉及2个页面（我想是因为该页面中的错误表明彼此相关）。在我的menuUser.dart中，我已将图标（就像购物车一样，但不是因为我没有从事电子商务项目）放在此dart文件中，因为我已经放置了默认标签。因此，我只是将图标放在注销图标旁边。
因此，当我单击该图标时，应该转到产品购物车页面（AttractionCalc.dart）的下一页，以更新数量并获取总价（类似于电子商务应用程序）。
我的问题是，当我运行该应用程序时，当我单击该图标时，我在终端中收到此错误：
I/flutter (26976): ══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════
I/flutter (26976): The following _TypeError was thrown building AttractionCalc(dirty, state:
I/flutter (26976): _AttractionCalcState#57db7):
I/flutter (26976): type 'bool' is not a subtype of type 'Widget'
I/flutter (26976):
I/flutter (26976): The relevant error-causing widget was:
I/flutter (26976): AttractionCalc file:///C:/myapp/lib/screen/menuUser.dart:97:59
I/flutter (26976):
I/flutter (26976): When the exception was thrown, this was the stack:
I/flutter (26976): #0 _AttractionCalcState.build (package:myapp/view/attractionCalc.dart:172:31)
I/flutter (26976): #1 StatefulElement.build (package:flutter/src/widgets/framework.dart:4619:28)
I/flutter (26976): #2 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:4502:15)
I/flutter (26976): #3 StatefulElement.performRebuild (package:flutter/src/widgets/framework.dart:4675:11)
I/flutter (26976): #4 Element.rebuild (package:flutter/src/widgets/framework.dart:4218:5)
I/flutter (26976): #5 BuildOwner.buildScope (package:flutter/src/widgets/framework.dart:2627:33)
I/flutter (26976): #6 WidgetsBinding.drawFrame (package:flutter/src/widgets/binding.dart:883:20)
I/flutter (26976): #7 RendererBinding._handlePersistentFrameCallback (package:flutter/src/rendering/binding.dart:284:5)
I/flutter (26976): #8 SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:1113:15)
I/flutter (26976): #9 SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:1052:9)
I/flutter (26976): #10 SchedulerBinding._handleDrawFrame (package:flutter/src/scheduler/binding.dart:968:5)
I/flutter (26976): #14 _invoke (dart:ui/hooks.dart:261:10)
I/flutter (26976): #15 _drawFrame (dart:ui/hooks.dart:219:3)
I/flutter (26976): (elided 3 frames from dart:async)
I/flutter (26976):
I/flutter (26976): ════════════════════════════════════════════════════════════════════════════════════════════════════
这是我的menuUser.dart代码：
import 'dart:convert';
import 'package:device_info/device_info.dart';
import 'package:flutter/material.dart';
import 'package:http/http.dart' as http;
import 'package:myapp/model/api.dart';
import 'package:myapp/network/network.dart';
import 'package:myapp/view/attractionCalc.dart';
import 'package:myapp/view/home.dart';
import 'package:myapp/view/budget.dart';
import 'package:myapp/view/locationMap.dart';
import 'package:myapp/view/profile.dart';
import 'package:shared_preferences/shared_preferences.dart';
class MenuUsers extends StatefulWidget {
final VoidCallback signOut;
MenuUsers(this.signOut);
@override
_MenuUsersState createState() => _MenuUsersState();
}
class _MenuUsersState extends State<MenuUsers> {
signOut(){
setState((){
widget.signOut();
});
}
DeviceInfoPlugin deviceInfo = DeviceInfoPlugin();
String deviceID;
getDeviceInfo()async{
AndroidDeviceInfo androidInfo = await deviceInfo.androidInfo;
print("Device Info : ${androidInfo.id}");
setState(() {
deviceID = androidInfo.id;
});
}
String name = "";
TabController tabController;
getPref()async{
SharedPreferences preferences = await SharedPreferences.getInstance();
setState(() {
name = preferences.getString("name");
});
}
@override
void initState() {
// TODO: implement initState
super.initState();
getPref();
}
// total prices
var loadingTotalPrice = false;
var totalCart = "0";
getTotalPrice() async {
setState(() {
loadingTotalPrice = true;
});
final response = await http.get(NetworkUrl.getTotalPrice(deviceID));
if (response.statusCode == 200) {
final data = jsonDecode(response.body)[0];
String total = data['total'];
setState(() {
loadingTotalPrice = false;
totalCart = total;
});
} else {
setState(() {
loadingTotalPrice = false;
});
}
}
@override
Widget build(BuildContext context) {
return DefaultTabController(
length: 4,
child: Scaffold(
appBar: AppBar(
title: Text("TravB",
style: TextStyle(fontSize: 25,),
),
backgroundColor: Colors.pink,
actions: <Widget>[
IconButton(
onPressed: (){
Navigator.push(context,
MaterialPageRoute(builder: (context) => AttractionCalc()));
},
icon: Icon(Icons.note_add),
),
IconButton(
onPressed: (){
signOut();
},
icon: Icon(Icons.lock),
)
],
),
body: TabBarView(
children: <Widget>[
Home(),
Budget(),
LocationMap(),
Profile(),
],
),
bottomNavigationBar: TabBar(
labelColor: Colors.pink,
unselectedLabelColor: Colors.grey,
indicator: UnderlineTabIndicator(
borderSide: BorderSide(
style: BorderStyle.none
)
),
tabs: <Widget>[
Tab(
icon: Icon(Icons.home),
text: "Home",
),
Tab(
icon: Icon(Icons.view_list),
text: "Wishlist",
),
Tab(
icon: Icon(Icons.map),
text: "Location",
),
Tab(
icon: Icon(Icons.person),
text: "Profile",
)
],
),
),
);
}
}
这是我的AttractionCalc.dart代码：
import 'dart:convert';
import 'package:device_info/device_info.dart';
import 'package:flutter/material.dart';
import 'package:http/http.dart' as http;
import 'package:myapp/model/attractionCalcModel.dart';
import 'package:myapp/network/network.dart';
class AttractionCalc extends StatefulWidget {
@override
_AttractionCalcState createState() => _AttractionCalcState();
}
class _AttractionCalcState extends State<AttractionCalc> {
List<AttractionCalcModel> list = [];
DeviceInfoPlugin deviceInfo = DeviceInfoPlugin();
getDeviceInfo()async{
AndroidDeviceInfo androidInfo = await deviceInfo.androidInfo;
print("Device Info : ${androidInfo.id}");
setState(() {
unikID = androidInfo.id;
});
_fetchData();
}
String unikID;
var loading = false;
var cekData = false;
_fetchData() async {
setState(() {
loading = true;
});
list.clear();
final response = await http.get(NetworkUrl.getProductCalc(unikID));
if (response.statusCode == 200) {
if (response.contentLength == 2) {
setState(() {
loading = false;
cekData = false;
});
} else {
final data = jsonDecode(response.body);
setState(() {
for (Map i in data ) {
list.add(AttractionCalcModel.fromJson(i));
}
loading = false;
cekData = true;
});
getSummaryAmount();
}
} else {
setState(() {
loading = false;
cekData = false;
});
}
}
var totalPrice = "0";
getSummaryAmount() async {
setState(() {
loading = true;
});
final response = await http.get(NetworkUrl.getSummaryAmountCalc(unikID));
if (response.statusCode == 200) {
final data = jsonDecode(response.body)[0];
String total = data['total'];
setState(() {
loading = false;
totalPrice = total;
});
} else {
setState(() {
loading = false;
});
}
}
_addQuantity(AttractionCalcModel model, String tipe) async {
await http.post(NetworkUrl.updateQuantity(), body: {
"idAttraction" : model.id,
"unikID" : unikID,
"tipe" : tipe,
});
_fetchData();
}
@override
void initState() {
// TODO: implement initState
super.initState();
getDeviceInfo();
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text("Calculate Attraction Prices"),
elevation: 1,
),
body: Container(
padding: EdgeInsets.all(16),
child: loading ? Center(
child: CircularProgressIndicator(),
)
: cekData
? Column(
crossAxisAlignment: CrossAxisAlignment.stretch,
children: <Widget>[
Expanded(
child: ListView.builder(
itemCount: list.length,
shrinkWrap: true,
physics: ClampingScrollPhysics(),
itemBuilder: (context, i){
final a = list[i];
return Container(
child: Row(
children: <Widget>[
Expanded(
child: Column(
crossAxisAlignment: CrossAxisAlignment.stretch,
children: <Widget>[
Text(a.attractionName),
Text("Price : RM ${a.price}"),
Container(
padding: EdgeInsets.symmetric(
vertical: 2
),
child: Divider(
color: Colors.grey,
)
)
],
),
),
Container(
child: IconButton(
onPressed: (){
_addQuantity(a, "tambah");
},
icon: Icon(Icons.add),
),
),
Container(
child: Text("${a.qty}"),
),
Container(
child: IconButton(
onPressed: (){
_addQuantity(a, "kurang");
},
icon: Icon(Icons.remove),
),
)
],
)
);
},
),
),
totalPrice == "0" ?? SizedBox(),
Container(
padding: EdgeInsets.all(16),
child: Text("Total Budget : RM ${totalPrice.toString()}"),
)
],
)
: Column(
crossAxisAlignment: CrossAxisAlignment.stretch,
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text("You don't have any places to be calculate",
textAlign: TextAlign.center,
style: TextStyle(
fontSize: 18, fontWeight: FontWeight.bold
),)
],
)
),
);
}
}
请让我知道我哪里出了错，我是Flutter的新手。这是我的最后一年的项目，我真的需要一些帮助。
答案 0 :(得分：1)
由于totalPrice == "0" ?? SizedBox()，您收到此错误。
您可以像以前一样将ternary operator用于if checks。
请参见下面的代码示例：
totalPrice == "0" ? SizedBox() : Container( padding: EdgeInsets.all(16),child: Text("Total Budget : RM ${totalPrice.toString()}"),)