颤振问题：如何更新购物车中的商品数量？

Question

我实现添加到购物车功能项目成功添加到购物车但数量当我重新加载飞镖页面时，购物车徽章中的计数未更新超过计数更新的数量。有人可以帮助我吗？

我实现了将添加到购物车的功能项目成功添加到购物车中，但是当我重新加载飞镖页面时，购物车徽章中的计数数量没有更新，而不是计数更新的数量。有人可以帮我吗？ 这是我的主页.dart

import 'dart:convert';

import 'package:flutter/material.dart';
import 'package:badges/badges.dart';
import 'package:hospital/BestDeatProducts/best_deal_product_page.dart';
import 'package:hospital/CartPage/pages/cartPage.dart';
import 'package:hospital/Drawer/dropdown_menu.dart';
import 'package:hospital/FirstSection/carousel.dart';
import 'package:hospital/Drawer/drawercontent.dart';
import 'package:hospital/FloatingActionButton/ConsultWithDoctor/consult_with_doctor.dart';
import 'package:hospital/MedicineCateory/medicine_category_page.dart';
import 'package:hospital/SecondSection/second_page.dart';

import 'package:hospital/ThirdSection/third_page.dart';
import 'package:hospital/TrendingProducts/trending_product_page.dart';
import 'package:hospital/constant.dart';
import 'package:hospital/customApiVariable.dart';
import 'package:provider/provider.dart';
import 'package:shared_preferences/shared_preferences.dart';

import 'No Internet/connectivity_provider.dart';
import 'No Internet/no_internet.dart';
import 'package:http/http.dart' as http;

class HomePage extends StatefulWidget {
  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  SharedPreferences loginData;
  // late String username;

  Future getUsername() async {
    loginData = await SharedPreferences.getInstance();
    setState(() {
      // print("uname" + uname.toString());
      print("dddpppuu1 : responceData_un" +
          loginData.getString('responceData_un').toString());
      print("dddpppuu2 : responceData_ue" +
          loginData.getString('responceData_ue').toString());
      print("dddpppuu3 : responceData_status" +
          loginData.getString('responceData_status').toString());
      String responceData_uid =
          loginData.getString('responceData_uid').toString();
    
      fetchData(responceData_uid);
    });
  }


  var response;

  var addToCartApi;

  @override
  void initState() {
    // TODO: implement initState
    //
    super.initState();

    Provider.of<ConnectivityProvider>(context, listen: false).startMonitering();
// for loading
    getUsername();
  }

  fetchData(String argResponceData_uid) async {
    var api = Uri.parse(
        '$ecommerceBaseUrl/addToCartApi.php?a2rTokenKey=$a2rTokenKey&action=addToCartList&uid=${argResponceData_uid}');
    print('cartpage' + api.toString());

    response = await http.get(api);

    print("Carousel" + response.body);

    addToCartApi = jsonDecode(response.body);
    print('addToCartApi' + addToCartApi['total'].toString());

    print('totalPriceAfterOffer' + totalPriceAfterOffer.toString());

    setState(() {});
  }


  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          backgroundColor: kGreen,
          title: Text(
            "BK Arogyam",
            style: TextStyle(fontStyle: FontStyle.italic),
          ),
          actions: [
            
            response != null
                ? Badge(
                    position: BadgePosition.topEnd(top: 3, end: 18),
                    animationDuration: Duration(milliseconds: 300),
                    animationType: BadgeAnimationType.slide,
                    badgeContent: Text(
                      addToCartApi['total']['num'].toString(),
                      style: TextStyle(color: Colors.white),
                    ),
                    child: IconButton(
                        icon: Icon(Icons.shopping_cart),
                        padding: EdgeInsets.only(right: 30.0),
                        onPressed: () {
                          Navigator.push(
                            context,
                            MaterialPageRoute(builder: (context) => Cartpage()),
                          );
                        }),
                  )
                : IconButton(
                    icon: Icon(Icons.shopping_cart),
                    // onPressed: () => print("open cart"),
                    onPressed: () {
                      Navigator.push(
                        context,
                        MaterialPageRoute(builder: (context) => Cartpage()),
                      );
                    },
                  ),
            DropDownMenu(),
          ],
        ),
        floatingActionButton: FloatingActionButton(
          backgroundColor: kGreen,
          onPressed: () => Navigator.push(context,
              MaterialPageRoute(builder: (context) => ConsultWithDoctor())),
          tooltip: 'Consult With Doctor',
          child: Container(
            child: Image(
              image: AssetImage(
                "assets/icons/cwd.png",
              ),
              color: Colors.white,
              width: 40,
              height: 40,
            ),
          ),
        ),
        drawer: Drawer(
          child: DrawerContent(),
        ),
        body: pageUI());
  }

  Widget pageUI() {
    return Consumer<ConnectivityProvider>(
      builder: (consumerContext, model, child) {
        if (model.isOnline != null) {
          return model.isOnline
              ? ListView(
                  children: [
                    Carousel(),
                    SizedBox(
                      height: 10.0,
                    ),
                    MedicineCategoryPage(),
                    SizedBox(
                      height: 10.0,
                    ),
                    SecondPage(),
                    SizedBox(
                      height: 10.0,
                    ),
                    ThirdPage(),
                    SizedBox(
                      height: 10.0,
                    ),
                    TrendingProductPage(),
                    SizedBox(
                      height: 16.0,
                    ),
                    BestDealProductPage(),
                    SizedBox(
                      height: 10.0,
                    ),
                  ],
                )
              : NoInternet();
        }
        return Container(
          child: Center(
            child: CircularProgressIndicator(),
          ),
        );
      },
    );
  }
}

Answer 1

您可以使用提供程序包提供的更改通知器。

并观看有关如何使用的视频，完全适合您的用例搜索 YouTube 更改通知提供程序由不断增长的开发人员提供

希望对你有帮助?

Answer 2

您可以使用 provider(provider: ^5.0.0) 或 Getx(get: ^4.1.4) 来处理这种情况。 GetX 和 Provider 有很多例子。

如果您不想使用其中任何一个，则将您的购物车/徽章计数存储到 tempCartCount 变量（示例：int cartCount = 0）并将其设置为徽章计数而不是“addToCartApi['total'][ 'num'].toString()" , 确保在 update/addCart Item 上设置状态。

这里我提供了一个如何更新 appBar 计数的简单示例。

如果您想从任何其他屏幕进行更改，请将 cartCount 设置为全局，否则您可以将其设置为本地/私有。

import 'package:badges/badges.dart';
import 'package:flutter/material.dart';

class UpdateCountExample extends StatefulWidget {
  @override
  _UpdateCountExampleState createState() => _UpdateCountExampleState();
}

int cartCount = 0;

class _UpdateCountExampleState extends State<UpdateCountExample> {
  List<String> cartArray = [];

  @override
  void initState() {
    WidgetsBinding.instance!.addPostFrameCallback((timeStamp) {
      setState(() {
        cartCount = 0;
      });
    });
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("App Bar"),
        actions: [
          Padding(
            padding: const EdgeInsets.only(right: 18.0, top: 5.0),
            child: Badge(
              badgeContent: Text(cartCount.toString()),
              child: Icon(Icons.add_shopping_cart),
            ),
          )
        ],
      ),
      body: Container(
        alignment: Alignment.center,
        padding: EdgeInsets.all(20),
        child: Column(
          mainAxisSize: MainAxisSize.min,
          mainAxisAlignment: MainAxisAlignment.center,
          crossAxisAlignment: CrossAxisAlignment.center,
          children: [
            Text(
              "Add item in cart",
              textAlign: TextAlign.center,
              style: TextStyle(fontWeight: FontWeight.bold, fontSize: 18, decoration: TextDecoration.none, color: Colors.black),
            ),
            SizedBox(
              height: 20,
            ),
            InkWell(
              onTap: () {
                setState(() {
                  cartArray.add("value ${cartArray.length}");
                  cartCount = cartArray.length;
                });
              },
              child: Container(
                padding: const EdgeInsets.all(10.0),
                color: Colors.amber,
                child: Text(
                  "Add Item",
                  textAlign: TextAlign.center,
                  style: TextStyle(fontSize: 15, decoration: TextDecoration.none, color: Colors.black),
                ),
              ),
            ),
            Expanded(
              child: ListView.builder(
                  shrinkWrap: true,
                  itemCount: cartArray.length,
                  itemBuilder: (context, index) {
                    return Text(
                      cartArray[index],
                      style: TextStyle(fontSize: 20, color: Colors.black),
                    );
                  }),
            )
          ],
        ),
      ),
    );
  }
}