由于不需要的键，无法遍历 JSON 对象答案

【问题标题】：Cannot iterate through the JSON object because of the unwanted keys由于不需要的键，无法遍历 JSON 对象
【发布时间】：2020-07-10 15:00:06
【问题描述】：

我的 JSON 响应对象是这样的

{
    "response": "success",
    "message": "done",
    "data": {
        "orders": {
            "order4": {
                "OrderId": "4",
                "OrderSubTotal": "568",
                "Items": {
                    "1": {
                        "ProductName": "Prod 1",
                        "ItemDiscount": "10",
                        "Quantity": "3",
                        "TotalItemPrice": "161.865"
                    },
                    "2": {
                        "ProductName": "Prod 2",
                        "ItemDiscount": "0",
                        "Quantity": "5",
                        "TotalItemPrice": "449.75"
                    }
                },
                "order6": {
                    "OrderId": "6",
                    "total": "789",
                    "Items": {
                        "1": {
                            "ProductName": "Prod 1",
                            "ItemDiscount": "10",
                            "Quantity": "3",
                            "TotalItemPrice": "161.865"
                        },
                        "2": {
                            "ProductName": "Prod 2",
                            "ItemDiscount": "0",
                            "Quantity": "5",
                            "TotalItemPrice": "449.75"
                        }
                    }
                }

            }
        }
    }
}

问题是我无法遍历这些字段，因为我得到了像 order6、order4 这样的随机键。那么有没有办法从对象中删除这些键并创建一个干净的 JSON 对象。我用飞镖语言编码。

【问题讨论】：

您使用的是哪种语言？
带有 dart 的颤振框架。我在描述中添加了这一点。
你的 json 是一个字符串？
你这是什么意思？
我的意思是如果json只是一个字符串，所以我们需要先序列化它。

标签： json flutter dart httprequest

【解决方案1】：

如果我知道你想要什么，那么SplayTreeMap.from(map, comparator) 可以为你完成这项工作，如下代码所示：

import 'dart:convert';
import 'dart:collection';

void main() {
  String str = r'''{
    "response": "success",
    "message": "done",
    "data": {
        "orders": {
            "order6": {
                "OrderId": "6",
                "total": "789",
                "Items": {
                    "1": {
                        "ProductName": "Prod 1",
                        "ItemDiscount": "10",
                        "Quantity": "3",
                        "TotalItemPrice": "161.865"
                    },
                    "2": {
                        "ProductName": "Prod 2",
                        "ItemDiscount": "0",
                        "Quantity": "5",
                        "TotalItemPrice": "449.75"
                    }
                }
            },
            "order4": {
                "OrderId": "4",
                "OrderSubTotal": "568",
                "Items": {
                    "1": {
                        "ProductName": "Prod 1",
                        "ItemDiscount": "10",
                        "Quantity": "3",
                        "TotalItemPrice": "161.865"
                    },
                    "2": {
                        "ProductName": "Prod 2",
                        "ItemDiscount": "0",
                        "Quantity": "5",
                        "TotalItemPrice": "449.75"
                    }
                }
            }
        }
    }
}''';
  
  final sortedMap = new SplayTreeMap<String,dynamic>.from(jsonDecode(str)["data"]["orders"], (a,b)=>a.compareTo(b));
  print(sortedMap);
}

【讨论】：

【解决方案2】：

看看我根据你提供的 json 制作的这个例子：

以下是您提供的示例 json：

{
    "response": "success",
    "message": "done",
    "data": {
        "orders": {
            "order6": {
                "OrderId": "6",
                "total": "789",
                "Items": {
                    "1": {
                        "ProductName": "Prod 1",
                        "ItemDiscount": "10",
                        "Quantity": "3",
                        "TotalItemPrice": "161.865"
                    },
                    "2": {
                        "ProductName": "Prod 2",
                        "ItemDiscount": "0",
                        "Quantity": "5",
                        "TotalItemPrice": "449.75"
                    }
                }
            },
            "order4": {
                "OrderId": "4",
                "OrderSubTotal": "568",
                "Items": {
                    "1": {
                        "ProductName": "Prod 1",
                        "ItemDiscount": "10",
                        "Quantity": "3",
                        "TotalItemPrice": "161.865"
                    },
                    "2": {
                        "ProductName": "Prod 2",
                        "ItemDiscount": "0",
                        "Quantity": "5",
                        "TotalItemPrice": "449.75"
                    }
                }
            }
        }
    }
}

基于 json 我为您制作了一个 ui 来显示订单详情：

import 'dart:convert';

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(home: HomePage());
  }
}

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

class _HomePageState extends State<HomePage> {
  List<Order> ordersList = List();
  @override
  void initState() {
    super.initState();
    getData();
  }

  getData() async {
    String data =
        await DefaultAssetBundle.of(context).loadString("json/parse.json");

    Map newMap = json.decode(data);

    newMap['data'].forEach((k, v) {
      
      v.forEach((key, val) {
        String ordername = key;
        List<Item> items = List();
       
        
        val['Items'].forEach((key, value) {
          print('sample');
          Item item = Item(
            productNumber: key,
            productName: value['ProductName'],
            itemDiscount: value['ItemDiscount'],
            quantity: value['Quantity'],
            totalItemPrice: value['TotalItemPrice'],
          );
          items.add(item);

          print(key);
          print(value);
          print('length is :${items.length}');
        });

        Order order = Order(
            orderId: val['OrderId'],
            orderName: ordername,
            total: val['total'],
            items: items);

        ordersList.add(order);
      });
    });
    setState(() {});

    print('This is the list : count ${ordersList.length}');
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        body: Container(
      child: ListView.builder(
          itemCount: ordersList.length,
          shrinkWrap: true,
          itemBuilder: (context, index) {
            var order = ordersList[index];
            return Card(
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: <Widget>[
                  Text('Order Name : ${order.orderName}'),
                  Text('Order Id : ${order.orderId}'),
                  Text('Order total : ${order.total}'),
                  Text('Order Items: ${order.items.length}')
                ],
              ),
            );
          }),
    ));
  }
}

class Order {
  final String orderName;
  final String orderId;
  final String total;
  final List<Item> items;

  Order({this.orderName, this.orderId, this.total, this.items});
}

class Item {
  Item({
    this.productName,
    this.itemDiscount,
    this.quantity,
    this.totalItemPrice,
    this.productNumber,
  });
  String productNumber;
  String productName;
  String itemDiscount;
  String quantity;
  String totalItemPrice;
}

也许我很困惑的是您提供的 json 是否正确，请检查它在 order 4 中是否有 order6，并且 OrderSubTotal 和 total 有关心的参数，如果事情正确，请告诉我。

检查一下，让我知道它是否有效

【讨论】：