类型“_InternalLinkedHashMap<String，dynamic>”不是类型转换中的“List<dynamic>”类型的子类型

Question

我正尝试在Dart中反序列化一个非常复杂的JSON，但是我不知道出了什么问题。

当它试图反序列化时，它向我显示了这个错误：“类型'_InternalLinkedHashMap‘不是类型转换中类型'List’的子类型”

有人知道这是怎么回事吗？

下面是我的代码：

Json

{
  "Instytucja": [
    "TypInstytucji": "bank krajowy",
      "PodtypInstytucji": "bank centralny",
      "NrInstytucji": 101,
      "NazwaInstytucji": "Narodowy Bank Polski",
      "SymbolLiterowy": "NBP",
      "DataRozpDzial": "1945-01-15",
      "NIP": 5250008198,
      "IdentyfikatorLEI": "549300K7Z2KT76WQJD18",
      "WWW": "www.nbp.pl",
        "Jendostka": [
        {
          "NrEwidencyjny": "A000001",
          "TypJednostki": "Centrala",
          "NazwaJednostki": "Centrala",
          "SymbolLiterowy": "C-la",
          "DaneAdresowe": {
            "kraj": "POLSKA",
            "wojewodztwo": "MAZOWIECKIE",
            "powiat": "Warszawa",
            "miejscowosc": "Warszawa",
            "ulica": "ul. Świętokrzyska",
            "numerBudynku": "11/21",
            "kodPocztowy": "00-919",
            "poczta": "Warszawa",
            "nrSkrytkiPocztowej": 1011
          },
          "DataPodjeciaDzialalnosci": "1945-01-15",
          "NumerTelefonu": "22 185 10 10",
          "NumerFaksu": "22 185 23 09",
          "NumerRozliczeniowy": [
            {
              "NrRozliczeniowy": 10100000,
              "NazwaNumeru": "Centrala",
              "KodyBIC": [
                "BIC NBPLPLPWXXX",
                "BIC SEPA NBPLPLPWXXX"
              ],
              "DataWygenerowania": "1945-01-15"
            },
            {
              "NrRozliczeniowy": 10100055,
              "NazwaNumeru": "Centrala - B2B Collect",
              "KodyBIC": [
                "BIC NBPLPLPWXXX",
                "BIC SEPA NBPLPLPWXXX"
              ],
              "DataWygenerowania": "2008-04-01"
            },
            {
              "NrRozliczeniowy": 10100068,
              "NazwaNumeru": "Centrala - NBPCollect",
              "KodyBIC": [
                "BIC NBPLPLPWXXX",
                "BIC SEPA NBPLPLPWXXX"
              ],
              "DataWygenerowania": "2008-10-01"
            },
            {
              "NrRozliczeniowy": 10100071,
              "NazwaNumeru": "Centrala - B2B-2",
              "KodyBIC": [
                "BIC NBPLPLPWXXX",
                "BIC SEPA NBPLPLPWXXX"
              ],
              "DataWygenerowania": "2016-08-01"
            }
          ]
        },
  ]
 ]
}

实体

import 'package:equatable/equatable.dart';

abstract class Bank extends Equatable {
  List<Institution> get institutions;
}

abstract class Institution extends Equatable {
  List<Unit> get units;
}

abstract class Unit extends Equatable {
  List<SortNumber> get sortNumbers;
}

abstract class SortNumber extends Equatable {
  int get sortNumber;
}

模型

import 'package:jaki_to_bank/features/home/domain/entities/bank.dart';
import 'package:json_annotation/json_annotation.dart';

part 'bank_model.g.dart';

@JsonSerializable()
class BankModel extends Bank {
  BankModel({required this.institutions});

  factory BankModel.fromJson(Map<String, dynamic> json) => _$BankModelFromJson(json);

  @override
  @JsonKey(name: 'Instytucja')
  final List<InstitutionModel> institutions;

  @override
  List<Object?> get props => [institutions];
}

@JsonSerializable()
class InstitutionModel extends Institution {
  InstitutionModel({required this.units});

  factory InstitutionModel.fromJson(Map<String, dynamic> json) => _$InstitutionModelFromJson(json);

  @override
  @JsonKey(name: 'Jednostka')
  final List<UnitModel> units;

  @override
  List<Object?> get props => [units];
}

@JsonSerializable()
class UnitModel extends Unit {
  UnitModel({required this.sortNumbers});

  factory UnitModel.fromJson(Map<String, dynamic> json) => _$UnitModelFromJson(json);

  @override
  @JsonKey(name: 'NumerRozliczeniowy')
  final List<SortNumberModel> sortNumbers;

  @override
  List<Object?> get props => [sortNumbers];
}

@JsonSerializable()
class SortNumberModel extends SortNumber {
  SortNumberModel({required this.sortNumber});

  factory SortNumberModel.fromJson(Map<String, dynamic> json) => _$SortNumberModelFromJson(json);

  @override
  @JsonKey(name: 'NrRozliczeniowy')
  final int sortNumber;

  @override
  List<Object?> get props => [sortNumber];
}

数据源

import 'dart:convert';

import 'package:flutter/services.dart';
import 'package:jaki_to_bank/core/app/files.dart';
import 'package:jaki_to_bank/features/home/data/models/bank_model.dart';
import 'package:jaki_to_bank/features/home/domain/entities/bank.dart';

abstract class BanksDataSource {
  Future<Bank> getBanksList();
}

class BanksDataSourceImpl extends BanksDataSource {
  @override
  Future<Bank> getBanksList() async {
    final String source = Files.banks;

    final String banks = await rootBundle.loadString(source);
    final Map<String, dynamic> banksMap = jsonDecode(banks);

    return BankModel.fromJson(banksMap);
  }
}

堆栈跟踪

​

​

Answer 1

您的JSON格式不正确。

{
  "Instytucja": [
    {      <-- missing this
      "TypInstytucji": "bank krajowy",
      "PodtypInstytucji": "bank centralny",
      ...
    }
  ]
}

Answer 2

尝试将@JsonSerializable(explicitToJson: true)添加到您的InstitutionModel (以及任何有嵌套类的地方)，然后运行：

flutter pub run build_runner build --delete-conflicting-outputs

有关更多信息，请查看flutter.dev：https://flutter.dev/docs/development/data-and-backend/json?fbclid=IwAR2sA4lF5zRGneFH4KAqtYLLQXKF6dJqJ8QzmuY-NuEe-hiRPDUx5eNfRa8#generating-code-for-nested-classes