颤振错误：在 null 上调用了方法“[]”。接收者：null 尝试调用：[]("product")
当我点击我的购物车图标然后在这个页面中打开我的 carpage.dart 时，我的数据没有显示并给出错误，但是当我使用快速重新加载颤动页面时，该数据即将到来。 如何解决，请帮帮我。
错误=> 方法 '[]' 在 null 上被调用。接收者：空尝试调用：
这是我的cartPage.dart
import 'dart:convert';
import 'package:flutter/material.dart';
import 'package:hospital/CartPage/components/cartCard.dart';
import 'package:hospital/CartPage/components/priceDetailsCard.dart';
import 'package:hospital/constant.dart';
import 'package:hospital/customApiVariable.dart';
import 'package:http/http.dart' as http;
class Cartpage extends StatefulWidget {
@override
_CartpageState createState() => _CartpageState();
}
class _CartpageState extends State<Cartpage> {
var response;
var addToCartApi;
@override
void initState() {
super.initState();
fetchData();
}
fetchData() async {
var api = Uri.parse(
'$ecommerceBaseUrl/addToCartApi.php?a2rTokenKey=$a2rTokenKey&action=addToCartList&uid=${var_uid}');
response = await http.get(api);
print("Carousel" + response.body);
addToCartApi = jsonDecode(response.body);
print('addToCartApi' + addToCartApi['total'].toString());
// store in variable
totalOfferPrice = addToCartApi['total']['grandTotalOfferPrice'].toString();
totalPrice = addToCartApi['total']['grandTotalPrice'].toString();
totalPriceAfterOffer =
addToCartApi['total']['grandTotalPriceAfterOffer'].toString();
deliveryName = addToCartApi['total']['deliveryName'];
deliveryCharge = addToCartApi['total']['deliveryCharge'].toString();
total_num = addToCartApi['total']['num'].toString();
setState(() {});
}
// List allItems = CartRepo().getAllCartItems();
@override
Widget build(BuildContext context) {
final _media = MediaQuery.of(context).size;
return Scaffold(
appBar: AppBar(
backgroundColor: kGreen,
title: Text("My Cart"),
),
body: Stack(
children: [
Container(
decoration: BoxDecoration(color: Color(0xFFeeeeee)),
height: _media.height,
width: _media.width,
),
ListView(
shrinkWrap: true,
children: <Widget>[
CartCard(user_id: var_uid),
PriceDetailsCard(totalItem: addToCartApi['total']),
SizedBox(
height: 100,
)
],
),
Align(
alignment: Alignment.bottomCenter,
child: Container(
width: _media.width,
height: _media.height * .08,
decoration: BoxDecoration(color: Colors.white, boxShadow: [
BoxShadow(color: Colors.black87, blurRadius: 5.0),
BoxShadow(color: Colors.white, blurRadius: 10.0),
]),
child: Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: <Widget>[
Padding(
padding: const EdgeInsets.only(left: 10.0),
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text(
"\u20B9 ${totalPriceAfterOffer}",
style: TextStyle(
fontWeight: FontWeight.bold, fontSize: 20),
),
Text(
"View price details",
style: TextStyle(
color: Colors.blueGrey,
fontWeight: FontWeight.bold),
)
],
),
),
Padding(
padding: const EdgeInsets.only(right: 10.0),
child: Container(
width: _media.width * .4,
child: RaisedButton(
onPressed: () {},
color: kGreen,
child: Text(
"PLACE ORDER",
style: TextStyle(color: Colors.white),
),
)),
),
],
),
),
)
],
));
}
}
这是 CartCard.dart 页面
import 'dart:convert';
import 'package:flutter/material.dart';
// import 'package:hospital/FourthDelete/fourth_delete.dart';
// import 'package:hospital/FourthSection/MedicineProductList/medicine_product_list.dart';
import 'package:hospital/ProductDetailsPage/product_detailPage.dart';
import 'package:hospital/SecondSection/Medicine/medicine_page.dart';
import 'package:hospital/constant.dart';
import 'package:hospital/customApiVariable.dart';
import 'package:http/http.dart' as http;
class CartCard extends StatefulWidget {
final user_id;
const CartCard({Key key, this.user_id}) : super(key: key);
@override
_CartCardState createState() => _CartCardState();
}
class _CartCardState extends State<CartCard> {
var response;
//this drinks call from api
var cartCardApi;
@override
void initState() {
// TODO: implement initState
//
super.initState();
// for loading
fetchData(widget.user_id);
}
fetchData(auth_uid) async {
// var api = Uri.parse(
// 'https://www.a2rstore.in/oceonicApi/ecommerce/v2/api/categoryApi.php?a2rTokenKey=carpet1234');
// var api = Uri.parse('$baseUrl/productCatApi.php?a2rTokenKey=$a2rTokenKey');
var api = Uri.parse(
// '$ecommerceBaseUrl/addToCartApi.php?a2rTokenKey=$a2rTokenKey&action=addToCartList&uid=${widget.auth_uid}');
'$ecommerceBaseUrl/addToCartApi.php?a2rTokenKey=$a2rTokenKey&action=addToCartList&uid=${widget.user_id}');
// 'https://www.a2rstore.in/oceonicApi/ecommerce/v1/api/productSubCatApi.php?a2rTokenKey=a2rhos1234&pcat=60c461f032f2a');
response = await http.get(
api,
);
print("cartCardApi " + api.toString());
print("cartCardbody " + response.body);
// in double quotes drink is key value of json
cartCardApi = jsonDecode(response.body);
print("cartCardApi " + cartCardApi.toString());
return cartCardApi['product'];
// setState(() {});
}
String quantity = "1";
@override
Widget build(BuildContext context) {
final _media = MediaQuery.of(context).size;
return ListView.builder(
// itemCount: categoryApi.length.clamp(0, 3),//THis is for showed minimun length of item listview.builder flutter
itemCount: cartCardApi['product'].length,
scrollDirection: Axis.vertical,
physics: ScrollPhysics(),
shrinkWrap: true,
itemBuilder: (context, index) {
var cartCard = cartCardApi['product'][index];
return Container(
height: _media.height * .4,
child: Card(
color: Colors.white,
child: Column(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: <Widget>[
Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
Padding(
padding: const EdgeInsets.only(
left: 10.0, top: 10, bottom: 8),
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
Container(
width: _media.width * .6,
child: Text(
// widget.item.desc,
cartCard["productName"],
maxLines: 2,
style: TextStyle(
color: Colors.black,
fontSize: 18,
fontWeight: FontWeight.w500),
overflow: TextOverflow.ellipsis,
),
),
SizedBox(
height: 5,
),
Text(
// widget.item.quantity,
' Quantity ${cartCard['orderQuantity']}',
style:
TextStyle(color: Colors.grey, fontSize: 14),
),
SizedBox(
height: 10,
),
Row(
children: <Widget>[
Text(
"Seller: ",
style: TextStyle(
color: Colors.grey, fontSize: 14),
),
Icon(
Icons.check_circle,
color: Colors.grey,
size: 15,
)
],
),
SizedBox(
height: 15,
),
Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
crossAxisAlignment: CrossAxisAlignment.end,
children: <Widget>[
Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
Row(
mainAxisAlignment:
MainAxisAlignment.start,
children: <Widget>[
Text(
"\u20B9 " +
cartCard[
'productPriceAfterOffer'],
style: TextStyle(
fontWeight: FontWeight.bold,
fontSize: 23),
),
Padding(
padding:
const EdgeInsets.only(left: 10.0),
child: Text(
"\u20B9 " +
cartCard['productRealPrice'],
style: TextStyle(
color: Colors.grey,
decoration:
TextDecoration.lineThrough),
),
),
SizedBox(
width: 5,
),
Text(
'40' + "%off",
style: TextStyle(
color: Colors.green,
fontSize: 13,
fontWeight: FontWeight.w600),
)
],
),
SizedBox(
height: 10,
),
Text(
"2 offers available",
style: TextStyle(
color: Colors.green,
fontSize: 13,
fontWeight: FontWeight.w600),
)
],
)
],
)
],
),
),
Padding(
padding: const EdgeInsets.only(
top: 10.0, right: 8, bottom: 8),
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
Container(
color: Colors.white,
child: Row(
children: <Widget>[
Container(
width: _media.width * .3,
height: _media.height * .2,
child: Image.network(
// 'https://media.gettyimages.com/photos/woman-using-meal-delivery-service-through-mobile-app-picture-id1160735344?k=6&m=1160735344&s=612x612&w=0&h=tYEeckvNDyAoyUEfUeCii_29p_pBum_BVHKiUrGbjYY=',
cartCard['pImgImg'],
fit: BoxFit.cover,
),
)
],
),
),
Row(
children: <Widget>[
Text(
"Qty:",
style: TextStyle(fontWeight: FontWeight.bold),
),
SizedBox(
width: 10,
),
DropdownButton<String>(
value: quantity,
items: <String>["1", "2", "3", "4", "5"]
.map((String value) =>
DropdownMenuItem<String>(
value: value, child: Text(value)))
.toList(),
onChanged: (_value) {
setState(() {
quantity = _value;
});
},
)
],
),
],
),
)
],
),
Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: <Widget>[
Container(
height: _media.height * .08,
width: _media.width * .4875,
child: RaisedButton(
onPressed: () {},
color: Colors.white,
child: Row(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Icon(
Icons.favorite,
size: 15,
color: Colors.grey,
),
SizedBox(
width: 5,
),
Text(
"SAVE FOR LATER",
style: TextStyle(fontSize: 15),
)
],
),
),
),
Container(
height: _media.height * .08,
width: _media.width * .4875,
child: RaisedButton(
onPressed: () {},
color: Colors.white,
child: Row(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Icon(
Icons.delete,
size: 15,
color: Colors.grey,
),
SizedBox(
width: 5,
),
Text(
"REMOVE",
style: TextStyle(fontSize: 15),
)
],
),
),
),
],
)
],
),
),
);
});
}
}
这是我的json数据
{
"product": [
{
"plistId": "60c71ed46839f",
"plistPriceId": "",
"uid": "60daaedd3b9f8751161",
"orderQuantity": "1",
"date": "2021-07-06",
"productName": "MUKTI CHURNA",
"productCode": "499",
"productlink": "detail.php?pListName=MUKTI CHURNA&plistId=60c71ed46839f",
"productRealPrice": "1112",
"productPriceAfterOffer": 1110,
"productOfferAmountMulOrdrQuantity": 0,
"quantity": "1 p",
"pImgImg": "http:\/\/a2rstore.com\/inventory\/images\/product_images\/product-Mukti-Churan-600x600.jpg",
"subTotalRealPrice": 1110,
"subTotalofferPrice": 0,
"subTotalPriceAfterOffer": 1110
},
{
"plistId": "60cacee2ee4ff",
"plistPriceId": "",
"uid": "60daaedd3b9f8751161",
"orderQuantity": "1",
"date": "2021-07-06",
"productName": " PAIN CALM OIL",
"productCode": "504",
"productlink": "detail.php?pListName= PAIN CALM OIL&plistId=60cacee2ee4ff",
"productRealPrice": "123",
"productPriceAfterOffer": "123",
"productOfferAmountMulOrdrQuantity": 0,
"quantity": "1 p",
"pImgImg": "http:\/\/a2rstore.com\/inventory\/images\/product_images\/product-Oil-pulling-ff-600x600.jpg",
"subTotalRealPrice": 123,
"subTotalofferPrice": 0,
"subTotalPriceAfterOffer": 123
},
{
"plistId": "60cacee2ee4ff",
"plistPriceId": "",
"uid": "60daaedd3b9f8751161",
"orderQuantity": "3",
"date": "2021-07-06",
"productName": " PAIN CALM OIL",
"productCode": "504",
"productlink": "detail.php?pListName= PAIN CALM OIL&plistId=60cacee2ee4ff",
"productRealPrice": "123",
"productPriceAfterOffer": "123",
"productOfferAmountMulOrdrQuantity": 0,
"quantity": "1 p",
"pImgImg": "http:\/\/a2rstore.com\/inventory\/images\/product_images\/product-Oil-pulling-ff-600x600.jpg",
"subTotalRealPrice": 369,
"subTotalofferPrice": 0,
"subTotalPriceAfterOffer": 369
},
{
"plistId": "60cacee2ee4ff",
"plistPriceId": "",
"uid": "60daaedd3b9f8751161",
"orderQuantity": "3",
"date": "2021-07-06",
"productName": " PAIN CALM OIL",
"productCode": "504",
"productlink": "detail.php?pListName= PAIN CALM OIL&plistId=60cacee2ee4ff",
"productRealPrice": "123",
"productPriceAfterOffer": "123",
"productOfferAmountMulOrdrQuantity": 0,
"quantity": "1 p",
"pImgImg": "http:\/\/a2rstore.com\/inventory\/images\/product_images\/product-Oil-pulling-ff-600x600.jpg",
"subTotalRealPrice": 369,
"subTotalofferPrice": 0,
"subTotalPriceAfterOffer": 369
},
{
"plistId": "60cacee2ee4ff",
"plistPriceId": "",
"uid": "60daaedd3b9f8751161",
"orderQuantity": "1",
"date": "2021-07-06",
"productName": " PAIN CALM OIL",
"productCode": "504",
"productlink": "detail.php?pListName= PAIN CALM OIL&plistId=60cacee2ee4ff",
"productRealPrice": "123",
"productPriceAfterOffer": "123",
"productOfferAmountMulOrdrQuantity": 0,
"quantity": "1 p",
"pImgImg": "http:\/\/a2rstore.com\/inventory\/images\/product_images\/product-Oil-pulling-ff-600x600.jpg",
"subTotalRealPrice": 123,
"subTotalofferPrice": 0,
"subTotalPriceAfterOffer": 123
},
{
"plistId": "60cacee2ee4ff",
"plistPriceId": "",
"uid": "60daaedd3b9f8751161",
"orderQuantity": "1",
"date": "2021-07-06",
"productName": " PAIN CALM OIL",
"productCode": "504",
"productlink": "detail.php?pListName= PAIN CALM OIL&plistId=60cacee2ee4ff",
"productRealPrice": "123",
"productPriceAfterOffer": "123",
"productOfferAmountMulOrdrQuantity": 0,
"quantity": "1 p",
"pImgImg": "http:\/\/a2rstore.com\/inventory\/images\/product_images\/product-Oil-pulling-ff-600x600.jpg",
"subTotalRealPrice": 123,
"subTotalofferPrice": 0,
"subTotalPriceAfterOffer": 123
}
],
"total": {
"grandTotalOfferPrice": 0,
"grandTotalPrice": 123,
"grandTotalPriceAfterOffer": 123,
"deliveryName": "Shipping Charge",
"deliveryCharge": "Free",
"num": 6
}
}
3 个答案:
答案 0 :(得分：2)
根据错误，在您在 ListView 中访问它之前，您的 cartCardApi 为空。
如果是 API 调用，则使用 FutureBuilder 处理所有异步调用，例如显示加载、api 出错时出错，如果成功则 ui。
否则将cartCardApi 设为之前的空列表。
这样，当您调用 setState 时，新列表会更新，并且 ui 会获取新列表。
答案 1 :(得分：0)
当您尝试获取“产品”值时，您的 cartCardApi 似乎是 null。
答案 2 :(得分：0)
您尝试从产品中获取数据的方式似乎是错误的。尝试从响应中打印完整的 JSON 并打印每个单独的项目以查看正确的值。
这就是为什么首选 JSON 格式的原因，您可以在其中为响应值创建模型类，并将响应值映射到模型类中的预定义键，然后使用该模型类在 UI 中填充值。
避免这些类型的错误
https://medium.com/flutter-community/parsing-complex-json-in-flutter-747c46655f51
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