flutter - 防止覆盖抖动值

Question

在以下情况下，如何防止覆盖我的值。
我正在阅读Excel文件的每一行，将我的价格和产品保存在两个列表中，然后使用zip功能将这两个列表与第三个列表合并。

        for (var productsPricesStock in zip([
          products,
          prices,
          row.sublist(3, maxCols),
        ])) {
          standValues[productsPricesStock[0]] = {
            'name': productsPricesStock[0].toString(),
            'price': productsPricesStock[1].toString(),
            'stock': productsPricesStock[2].toString(),
          };
        }

然后，我保存此值(value) map

        if (!startingStock[tourNumber].contains(standName)) {
          Map standObject = {standName: standValues};
          startingStock[tourNumber].add(standObject);
        }

我的问题是我的条目被下一个的值覆盖:
例如，这是第一行的第一项:

这是第二行的第一项:

如您所见，第一行现在与第二行具有相同的条目:

每行都会发生这种情况，这意味着最后所有行都具有最后一行的值。
我很确定它与存储对值而不是值的引用有关，但是我不确定如何防止这种情况。
非常感谢您的帮助!
完整的功能代码:

  List<dynamic> products = [];
  List<dynamic> prices = [];
  Map<String, dynamic> startingStock = {};
  Map<String, dynamic> standValues = {};

 Future<void> _readExcel() async {
    try {
      var bytes = _tempFile.readAsBytesSync();
      var excel = Excel.decodeBytes(bytes);
      for (var table in excel.tables.keys) {
        int maxCols = excel.tables[table].maxCols;
        for (var row in excel.tables[table].rows) {
          if (row[2] == 'Produkt') {
            row.removeWhere(
                (product) => product == null || product == 'Produkt');
            products = row;
          }
          if (row[2] == 'Preis') {
            row.removeWhere((price) =>
                price == null || price == 'Stand' || price == 'Preis');
            prices = row;
          }
        }
        for (var row in excel.tables[table].rows) {
          if (row[0] != 'TP-Master' && row[0] != null && row[1] != null) {
            var tourNumber = row[0].toString();
            var standName = row[1].toString();
            if (!startingStock.containsKey(tourNumber)) {
              startingStock[tourNumber] = [];
            }

            if (!startingStock[tourNumber].contains(standName)) {
              Map standObject = {standName: standValues};
              startingStock[tourNumber].add(standObject);
            }

            for (var productsPricesStock in zip([
              products,
              prices,
              row.sublist(3, maxCols),
            ])) {
              standValues[productsPricesStock[0]] = {
                'name': productsPricesStock[0].toString(),
                'price': productsPricesStock[1].toString(),
                'stock': productsPricesStock[2].toString(),
              };
            }
          }
        }
      }
      successSnackBar('Die Datei wurde erfolgreich gelesen!');
    } catch (err) {
      print(err);
      errorSnackBar('Beim lesen der Datei ist ein Fehler aufgetreten!');
    }
  }

这是excel文件的一部分。
在第5行中，您可以看到所有产品。
在第6行中，您可以看到每种产品的价格。
在随后的各行中，您可以在第一列中看到游览编号和相关的商店名称以及商店每种产品的数量。
在我的代码中，我尝试以tournumber [shopname]格式存储数据，然后映射价格，产品名称和产品数量。

Excel测试:
https://docs.google.com/spreadsheets/d/1p9Z5yQ2u8sVDmEdbD9dYyYPwlQqdXWeZJp2BjvoexU4/edit?usp=sharing
结果将如下所示:




这就是用示例excel执行后的列表和 map 的样子。

    products = [
Spargel W, 
Spargel V, 
gestrig Spargel W, 
gestrigSpargel V, 
Erdbeer 1,  
Erdbeer 2
]
    prices = [10.90, 8.90, x, x, x, 2,50 ]
    startingStock = {
    'T1' : [U-Stephansplatz[
    Spargel W: {
    'name': Spargel W,
     'price': '10.9', 
    'stock': '30'
    }
    Spargel V: {
    ...
    } 
    Spargel W gestern: {
    ...
    } 
    ...
    ],
    Rugenbarg[
    Spargel W: {...}, 
    Spargel V: {...} 
    Spargel W gestern: {...} 
    ...]
    ] ...
    , 'T2': [
    Volksdorf : [
    Spargel W: {
    'name': Spargel W, 
    'price': '10.9', 
    'stock': '45'
    }
    Spargel V: {
    ...
    }
    Spargel W gestern: {
    ...
    } 
    ...],
    Poppenbüttel [
    Spargel W: {...}, 
    Spargel V: {...} 
    Spargel W gestern: {...} 
    ...]
    ] ...}

standValues仅包含当前行的值，因此在这种情况下，它将包含最后一行的值。 (T2站Fuhle Nord)

standValues = [Spargel W: {name: Spargel W, price: 10.9, stock: 23} Spargel V: ..., Spargel W gestrig: ..., ...]

Answer 1

我对您的代码进行了一些重构，并清理了一些类型，使它们更加具体。我希望这接近您想要的:

import 'dart:convert';
import 'dart:io';
import 'package:quiver/iterables.dart';
import 'package:excel/excel.dart';

Future<void> main() async {
  await _readExcel();
}

Future<void> _readExcel() async {
  final startingStock =
      <String, Map<String, Map<String, Map<String, String>>>>{};

  try {
    final bytes = File('StackOverflow.xlsx').readAsBytesSync();
    final excel = Excel.decodeBytes(bytes);

    for (final table in excel.tables.values) {
      final products = <String>[];
      final prices = <String>[];

      for (final row in table.rows) {
        if (row[2] == 'Produkt') {
          row.removeWhere(
              (Object product) => product == null || product == 'Produkt');
          products.addAll(row.map((Object e) => e.toString()));
        }
        if (row[2] == 'Preis') {
          row.removeWhere((Object price) =>
              price == null || price == 'Stand' || price == 'Preis');
          prices.addAll(row.map((Object e) => e.toString()));
        }
      }

      for (final row in table.rows) {
        if (row[0] != 'TP-Master' && row[0] != null && row[1] != null) {
          final tourNumber = row[0].toString();
          final standName = row[1].toString();
          final standValues = startingStock
              .putIfAbsent(tourNumber, () => {})
              .putIfAbsent(standName, () => {});

          for (final productsPricesStock in zip<dynamic>([
            products,
            prices,
            row.sublist(3, table.maxCols),
          ])) {
            standValues[productsPricesStock[0].toString()] = {
              'name': productsPricesStock[0].toString(),
              'price': productsPricesStock[1].toString(),
              'stock': productsPricesStock[2].toString(),
            };
          }
        }
      }
    }
    print(json.encode(startingStock));
    print('Die Datei wurde erfolgreich gelesen!');
  } catch (err) {
    print(err);
    print('Beim lesen der Datei ist ein Fehler aufgetreten!');
  }
}

以JSON格式输出:

{
   "T1":{
      "U-Stephansplatz":{
         "Spargel W":{
            "name":"Spargel W",
            "price":"10.9",
            "stock":"30.0"
         },
         "Spargel V":{
            "name":"Spargel V",
            "price":"8.9",
            "stock":"12.0"
         },
         "Spargel W gestrig":{
            "name":"Spargel W gestrig",
            "price":"x",
            "stock":"0.0"
         },
         "Spargel V gestrig":{
            "name":"Spargel V gestrig",
            "price":"x",
            "stock":"0.0"
         },
         "Erdbeer 1":{
            "name":"Erdbeer 1",
            "price":"x",
            "stock":"0.0"
         },
         "Erdbeer 2":{
            "name":"Erdbeer 2",
            "price":"2.5",
            "stock":"0.0"
         }
      },
      "Rugenbarg":{
         "Spargel W":{
            "name":"Spargel W",
            "price":"10.9",
            "stock":"25.0"
         },
         "Spargel V":{
            "name":"Spargel V",
            "price":"8.9",
            "stock":"124.0"
         },
         "Spargel W gestrig":{
            "name":"Spargel W gestrig",
            "price":"x",
            "stock":"0.0"
         },
         "Spargel V gestrig":{
            "name":"Spargel V gestrig",
            "price":"x",
            "stock":"0.0"
         },
         "Erdbeer 1":{
            "name":"Erdbeer 1",
            "price":"x",
            "stock":"0.0"
         },
         "Erdbeer 2":{
            "name":"Erdbeer 2",
            "price":"2.5",
            "stock":"34.0"
         }
      },
      "Blankenese":{
         "Spargel W":{
            "name":"Spargel W",
            "price":"10.9",
            "stock":"22.0"
         },
         "Spargel V":{
            "name":"Spargel V",
            "price":"8.9",
            "stock":"12.0"
         },
         "Spargel W gestrig":{
            "name":"Spargel W gestrig",
            "price":"x",
            "stock":"0.0"
         },
         "Spargel V gestrig":{
            "name":"Spargel V gestrig",
            "price":"x",
            "stock":"0.0"
         },
         "Erdbeer 1":{
            "name":"Erdbeer 1",
            "price":"x",
            "stock":"0.0"
         },
         "Erdbeer 2":{
            "name":"Erdbeer 2",
            "price":"2.5",
            "stock":"21.0"
         }
      },
      "Altona ZOB":{
         "Spargel W":{
            "name":"Spargel W",
            "price":"10.9",
            "stock":"22.0"
         },
         "Spargel V":{
            "name":"Spargel V",
            "price":"8.9",
            "stock":"42.0"
         },
         "Spargel W gestrig":{
            "name":"Spargel W gestrig",
            "price":"x",
            "stock":"0.0"
         },
         "Spargel V gestrig":{
            "name":"Spargel V gestrig",
            "price":"x",
            "stock":"0.0"
         },
         "Erdbeer 1":{
            "name":"Erdbeer 1",
            "price":"x",
            "stock":"0.0"
         },
         "Erdbeer 2":{
            "name":"Erdbeer 2",
            "price":"2.5",
            "stock":"22.0"
         }
      },
      "Holstenstraße":{
         "Spargel W":{
            "name":"Spargel W",
            "price":"10.9",
            "stock":"11.0"
         },
         "Spargel V":{
            "name":"Spargel V",
            "price":"8.9",
            "stock":"24.0"
         },
         "Spargel W gestrig":{
            "name":"Spargel W gestrig",
            "price":"x",
            "stock":"0.0"
         },
         "Spargel V gestrig":{
            "name":"Spargel V gestrig",
            "price":"x",
            "stock":"0.0"
         },
         "Erdbeer 1":{
            "name":"Erdbeer 1",
            "price":"x",
            "stock":"0.0"
         },
         "Erdbeer 2":{
            "name":"Erdbeer 2",
            "price":"2.5",
            "stock":"65.0"
         }
      }
   },
   "T2":{
      "Volksdorf":{
         "Spargel W":{
            "name":"Spargel W",
            "price":"10.9",
            "stock":"45.0"
         },
         "Spargel V":{
            "name":"Spargel V",
            "price":"8.9",
            "stock":"34.0"
         },
         "Spargel W gestrig":{
            "name":"Spargel W gestrig",
            "price":"x",
            "stock":"0.0"
         },
         "Spargel V gestrig":{
            "name":"Spargel V gestrig",
            "price":"x",
            "stock":"0.0"
         },
         "Erdbeer 1":{
            "name":"Erdbeer 1",
            "price":"x",
            "stock":"0.0"
         },
         "Erdbeer 2":{
            "name":"Erdbeer 2",
            "price":"2.5",
            "stock":"4.0"
         }
      },
      "Poppenbüttel":{
         "Spargel W":{
            "name":"Spargel W",
            "price":"10.9",
            "stock":"34.0"
         },
         "Spargel V":{
            "name":"Spargel V",
            "price":"8.9",
            "stock":"435.0"
         },
         "Spargel W gestrig":{
            "name":"Spargel W gestrig",
            "price":"x",
            "stock":"0.0"
         },
         "Spargel V gestrig":{
            "name":"Spargel V gestrig",
            "price":"x",
            "stock":"0.0"
         },
         "Erdbeer 1":{
            "name":"Erdbeer 1",
            "price":"x",
            "stock":"0.0"
         },
         "Erdbeer 2":{
            "name":"Erdbeer 2",
            "price":"2.5",
            "stock":"43.0"
         }
      },
      "Erdkampsweg":{
         "Spargel W":{
            "name":"Spargel W",
            "price":"10.9",
            "stock":"23.0"
         },
         "Spargel V":{
            "name":"Spargel V",
            "price":"8.9",
            "stock":"34.0"
         },
         "Spargel W gestrig":{
            "name":"Spargel W gestrig",
            "price":"x",
            "stock":"0.0"
         },
         "Spargel V gestrig":{
            "name":"Spargel V gestrig",
            "price":"x",
            "stock":"0.0"
         },
         "Erdbeer 1":{
            "name":"Erdbeer 1",
            "price":"x",
            "stock":"0.0"
         },
         "Erdbeer 2":{
            "name":"Erdbeer 2",
            "price":"2.5",
            "stock":"5.0"
         }
      },
      "Drosselstraße":{
         "Spargel W":{
            "name":"Spargel W",
            "price":"10.9",
            "stock":"432.0"
         },
         "Spargel V":{
            "name":"Spargel V",
            "price":"8.9",
            "stock":"53.0"
         },
         "Spargel W gestrig":{
            "name":"Spargel W gestrig",
            "price":"x",
            "stock":"0.0"
         },
         "Spargel V gestrig":{
            "name":"Spargel V gestrig",
            "price":"x",
            "stock":"0.0"
         },
         "Erdbeer 1":{
            "name":"Erdbeer 1",
            "price":"x",
            "stock":"0.0"
         },
         "Erdbeer 2":{
            "name":"Erdbeer 2",
            "price":"2.5",
            "stock":"6.0"
         }
      },
      "Fuhle Nord ":{
         "Spargel W":{
            "name":"Spargel W",
            "price":"10.9",
            "stock":"23.0"
         },
         "Spargel V":{
            "name":"Spargel V",
            "price":"8.9",
            "stock":"34.0"
         },
         "Spargel W gestrig":{
            "name":"Spargel W gestrig",
            "price":"x",
            "stock":"0.0"
         },
         "Spargel V gestrig":{
            "name":"Spargel V gestrig",
            "price":"x",
            "stock":"0.0"
         },
         "Erdbeer 1":{
            "name":"Erdbeer 1",
            "price":"x",
            "stock":"0.0"
         },
         "Erdbeer 2":{
            "name":"Erdbeer 2",
            "price":"2.5",
            "stock":"0.0"
         }
      }
   }
}