颤振错误：<异步挂起>
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【中文标题】颤振错误：<异步挂起>【英文标题】：Error in flutter : <asynchronous suspension> 【发布时间】：2021-09-18 21:30:20 【问题描述】：我想在产品添加成功后显示一个对话框，但是当我单击“添加到购物车”按钮时，我收到了图像中的那种错误。
这个对话框想要使用 httpException 显示，在我使用这个 httpExcetion 的 product_detailpage.dart 页面中，我使用了虚线。
这是我的 cart_api.dart 页面
import 'dart:convert';
import 'package:hospital/CartPage/Cart_Api/cart_http_exception.dart';
import 'package:hospital/customApiVariable.dart';
import 'package:http/http.dart' as http;
Future add_to_cart_fn(
String quantity, String plistId, String uid, String sid) async
var url = Uri.parse(
'$ecommerceBaseUrl/addToCartApi.php?a2rTokenKey=$a2rTokenKey&action=addToCart&uid=60daaedd3b9f8751161');
print('add_to_cart_url:' + url.toString());
final response = await http.post(url, headers:
"Accept": "Application/json"
, body:
"quantity": quantity,
"plistId": plistId,
"uid": uid,
"sid": sid,
);
print("ae" + response.body);
final convertderDatatoJson = jsonDecode(response.body);
try
if (convertderDatatoJson['status'] == "true")
print('status' + convertderDatatoJson['status']);
print('msg' + convertderDatatoJson['msg']);
throw HttpException(convertderDatatoJson['msg']);
catch (e)
throw e;
return convertderDatatoJson;
这是我的 httpException.dart 页面
class HttpException implements Exception
final msg;
HttpException(this.msg);
@override
String toString()
// TODO: implement toString
return msg;
这是我的 product_detailPage.dart 页面，
import 'dart:convert';
import 'package:carousel_pro/carousel_pro.dart';
import 'package:flutter/material.dart';
import 'package:hospital/CartPage/Cart_Api/cart_api.dart';
import 'package:hospital/CartPage/Cart_Api/cart_http_exception.dart';
import 'package:hospital/CartPage/pages/cartPage.dart';
import 'package:hospital/Drawer/dropdown_menu.dart';
import 'package:hospital/ProductDetailsPage/product_detailPage.dart';
import 'package:hospital/ProductDetailsPage/related_product_page.dart';
import 'package:hospital/SecondSection/Medicine/medicine_page.dart';
import 'package:hospital/constant.dart';
import 'package:hospital/customApiVariable.dart';
import 'package:http/http.dart' as http;
import 'package:line_icons/line_icons.dart';
import 'package:provider/provider.dart';
class DetailPage extends StatefulWidget
final plistId;
const DetailPage(Key key, this.plistId) : super(key: key);
@override
_DetailPageState createState() => _DetailPageState();
class _DetailPageState extends State<DetailPage>
final GlobalKey<FormState> _formKey = GlobalKey();
int quantity = 1;
var response;
var detailPageApi;
@override
void initState()
super.initState();
fetchData(widget.plistId);
fetchData(var consultWithDoctor) async
a2rTokenKey=carpet1234');
var api = Uri.parse(
'$ecommerceBaseUrl/productListApi.php?a2rTokenKey=$a2rTokenKey&plistId=$widget.plistId');
response = await http.get(
api,
);
print("detailPageApi " + api.toString());
print("detailPageBody " + response.body);
// in double quotes drink is key value of json
detailPageApi = jsonDecode(response.body);
print("detailPagelist " + detailPageApi.toString());
// return doctorDetailsApi;
setState(() );
@override
Widget build(BuildContext context)
return Scaffold(
appBar: AppBar(
backgroundColor: kGreen,
title: Text(
"Details",
style: TextStyle(fontStyle: FontStyle.italic),
),
actions: [
IconButton(
icon: Icon(Icons.shopping_cart),
// onPressed: () => print("open cart"),
onPressed: ()
Navigator.push(
context,
MaterialPageRoute(builder: (context) => Cartpage()),
);
,
),
DropDownMenu(),
],
),
body: Container(
child: response != null
? ListView.builder(
// itemCount: categoryApi.length.clamp(0, 3),//THis is for showed minimun length of item listview.builder flutter
itemCount: detailPageApi.length.clamp(0, 1),
scrollDirection: Axis.vertical,
physics: ScrollPhysics(),
shrinkWrap: true,
itemBuilder: (context, index)
var details = detailPageApi[index];
if (details['num'] == 0)
return Center(
child: CircularProgressIndicator(
backgroundColor: Colors.white,
),
);
return Column(
children: <Widget>[
Hero(
tag: "1",
child: SizedBox(
height: 300.0,
width: 300.0,
child: Carousel(
boxFit: BoxFit.cover,
autoplay: false,
animationCurve: Curves.fastOutSlowIn,
animationDuration: Duration(milliseconds: 800),
dotSize: 6.0,
dotIncreasedColor: Colors.black,
dotBgColor: Colors.transparent,
// dotPosition: DotPosition.topRight,
dotVerticalPadding: 10.0,
showIndicator: true,
indicatorBgPadding: 7.0,
images: [
NetworkImage(details['pImgImg']),
],
),
),
),
SizedBox(
height: 50,
),
Padding(
padding: const EdgeInsets.only(left: 20, right: 20),
child: Row(
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
Text(
"Name :",
style: TextStyle(
fontSize: 18,
height: 1.5,
fontWeight: FontWeight.w500),
),
SizedBox(
width: 20,
),
Flexible(
child: Text(
// widget.details,
details['productName'],
style: TextStyle(
fontSize: 17,
height: 1.5,
fontWeight: FontWeight.w500),
),
),
],
),
),
SizedBox(
height: 20,
),
Padding(
padding: const EdgeInsets.only(left: 20, right: 20),
child: Row(
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
Text(
"Details :",
style: TextStyle(
fontSize: 18,
height: 1.5,
fontWeight: FontWeight.w500),
),
SizedBox(
width: 20,
),
Flexible(
child: Text(
// widget.details,
details['productDescription'],
style: TextStyle(
fontSize: 17,
height: 1.5,
fontWeight: FontWeight.w500),
),
),
],
),
),
SizedBox(
height: 20,
),
Padding(
padding: const EdgeInsets.only(left: 20, right: 20),
child: Row(
children: <Widget>[
Text(
"Price :",
style: TextStyle(
fontSize: 18, fontWeight: FontWeight.w500),
),
SizedBox(
width: 20,
),
Row(
children: <Widget>[
Text(
// "Rs " + widget.pPromotionPrice,
"Rs 55.0",
style: TextStyle(
fontSize: 17,
fontWeight: FontWeight.w500),
),
SizedBox(
width: 20,
),
Text(
// "Rs " + widget.pPrice,
"Rs 100",
style: TextStyle(
fontSize: 18,
fontWeight: FontWeight.w500,
// color: warning,
decoration: TextDecoration.lineThrough),
)
],
)
],
),
),
SizedBox(
height: 25,
),
Padding(
padding: const EdgeInsets.only(right: 20, left: 20),
child: Row(
children: <Widget>[
Text(
"Qty :",
style: TextStyle(
fontSize: 17, fontWeight: FontWeight.w500),
),
SizedBox(
width: 20,
),
Row(
children: <Widget>[
InkWell(
onTap: ()
if (quantity > 1)
setState(()
quantity = --quantity;
);
// minus here
,
child: Container(
width: 25,
height: 25,
decoration: BoxDecoration(
// border: Border.all(color: primary),
shape: BoxShape.circle),
child: Icon(
LineIcons.minus,
size: 15,
),
),
),
SizedBox(
width: 15,
),
Text(
quantity.toString(),
style: TextStyle(fontSize: 16),
),
SizedBox(
width: 15,
),
InkWell(
onTap: ()
setState(()
quantity = ++quantity;
);
// minus here
,
child: Container(
width: 25,
height: 25,
decoration: BoxDecoration(
// border: Border.all(color: primary),
shape: BoxShape.circle),
child: Icon(
LineIcons.plus,
size: 15,
),
),
),
],
)
],
),
),
SizedBox(
height: 50,
),
InkWell(
onTap: () async
---------------------------------------------
//here show my msg using dialog box
try on HttpException catch (e)
print('hiii');
var errorMessage = 'Authentication Failed';
if (e.toString().contains(
'Product Succesfully Added to Cart'))
errorMessage =
'Product Succesfully Added to Cart';
print(errorMessage);
_showerrorDialog(errorMessage);
catch (error)
var errorMessage = 'Please try again later';
_showerrorDialog(errorMessage);
------------------------------------------------
var qty = quantity.toString();
var plistId = widget.plistId;
print('pplistid' + plistId);
var uid = var_uid.toString();
var sid = var_sid.toString();
print('uuid' + uid);
print('ssid' + sid);
var response =
await add_to_cart_fn(qty, plistId, uid, sid);
print("rsp: " + response['status']);
,
// ,
child: Padding(
padding: EdgeInsets.only(left: 20, right: 20),
child: Container(
height: 45,
width: double.infinity,
decoration: BoxDecoration(
color: kGreen,
borderRadius: BorderRadius.circular(30)),
child: Center(
child: Text(
"ADD TO CART",
style: TextStyle(
color: kWhite,
fontSize: 20,
),
),
),
),
),
),
SizedBox(height: 20.0),
// SomeMedicinePage(),
RelatedProductPage(plistId: widget.plistId)
],
);
)
: Center(
child: CircularProgressIndicator(
backgroundColor: Colors.white,
),
),
),
);
void _showerrorDialog(String message)
showDialog(
context: context,
builder: (ctx) => AlertDialog(
title: Text(
'An Error Occurs',
style: TextStyle(color: Colors.blue),
),
content: Text(message),
actions: <Widget>[
FlatButton(
child: Text('Okay'),
onPressed: () => Navigator.of(context, rootNavigator: true).pop())
],
),
);
【问题讨论】：
【参考方案1】：找到这个答案（不是我的）：
不是问题的指示，它只是表明代码执行不是逐行执行的同步代码，而是从调用堆栈中的某个位置开始的已完成 Future 的回调
来源： https://***.com/questions/60658945/asynchronous-suspension-in-stacktrace-output-in-flutter#:~:text=is%20not%20an,some%20position%20in%20the%20callstack.
【讨论】：
【参考方案2】：将该 api 或平台特定代码包装在 catch (e) 上的 try 和 catch 块中 do your stuff here error handling
【讨论】：
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