如何在Flutter中为指定JSON创建Model类并访问sub_asset_class_weight

报错原因 #

• 自动生成工具报错的核心原因是sub_asset_class_weight字段为嵌套异构数组：每个子数组的第一个元素是字符串类型、第二个是双精度浮点型，通用JSON转Dart工具默认会将数组识别为同类型元素，无法自动适配这种异构结构，因此生成无效代码。

完整Dart Model实现（空安全版本，无额外依赖） #

class AllocationResponse {
  final String statusMessage;
  final String statusCode;
  final dynamic error;
  final FinResult? finResult;

  AllocationResponse({
    required this.statusMessage,
    required this.statusCode,
    this.error,
    this.finResult,
  });

  factory AllocationResponse.fromJson(Map<String, dynamic> json) {
    return AllocationResponse(
      statusMessage: json['statusMessage'] as String,
      statusCode: json['statusCode'] as String,
      error: json['error'],
      finResult: json['finResult'] != null ? FinResult.fromJson(json['finResult']) : null,
    );
  }

  Map<String, dynamic> toJson() {
    return {
      'statusMessage': statusMessage,
      'statusCode': statusCode,
      'error': error,
      'finResult': finResult?.toJson(),
    };
  }
}

class FinResult {
  final int count;
  final AllocationResult? result;
  final int start;

  FinResult({
    required this.count,
    this.result,
    required this.start,
  });

  factory FinResult.fromJson(Map<String, dynamic> json) {
    return FinResult(
      count: json['count'] as int,
      result: json['result'] != null ? AllocationResult.fromJson(json['result']) : null,
      start: json['start'] as int,
    );
  }

  Map<String, dynamic> toJson() {
    return {
      'count': count,
      'result': result?.toJson(),
      'start': start,
    };
  }
}

class AllocationResult {
  final List<GeneratedAllocationItem>? generatedAllocation;
  final dynamic executedAllocation;

  AllocationResult({
    this.generatedAllocation,
    this.executedAllocation,
  });

  factory AllocationResult.fromJson(Map<String, dynamic> json) {
    final generatedAllocationList = json['generatedAllocation'] as List?;
    return AllocationResult(
      generatedAllocation: generatedAllocationList?.map((item) => GeneratedAllocationItem.fromJson(item)).toList(),
      executedAllocation: json['executedAllocation'],
    );
  }

  Map<String, dynamic> toJson() {
    return {
      'generatedAllocation': generatedAllocation?.map((item) => item.toJson()).toList(),
      'executedAllocation': executedAllocation,
    };
  }
}

class GeneratedAllocationItem {
  final List<MapEntry<String, double>> subAssetClassWeight;
  final double weight;
  final String asset;

  GeneratedAllocationItem({
    required this.subAssetClassWeight,
    required this.weight,
    required this.asset,
  });

  factory GeneratedAllocationItem.fromJson(Map<String, dynamic> json) {
    final subWeightList = json['sub_asset_class_weight'] as List;
    // 转换异构数组为MapEntry列表，方便后续访问
    final processedSubWeight = subWeightList.map((subItem) {
      final subList = subItem as List;
      return MapEntry(subList[0] as String, subList[1] as double);
    }).toList();

    return GeneratedAllocationItem(
      subAssetClassWeight: processedSubWeight,
      weight: json['weight'] as double,
      asset: json['asset'] as String,
    );
  }

  Map<String, dynamic> toJson() {
    // 转换回原始JSON要求的嵌套数组结构
    final originSubWeight = subAssetClassWeight.map((entry) => [entry.key, entry.value]).toList();
    return {
      'sub_asset_class_weight': originSubWeight,
      'weight': weight,
      'asset': asset,
    };
  }
}

访问sub_asset_class_weight的示例代码 #

// 示例：解析接口返回的JSON数据
Map<String, dynamic> jsonData = /* 你的接口JSON响应 */;
final allocationResponse = AllocationResponse.fromJson(jsonData);

// 遍历访问所有sub_asset_class_weight属性
if (allocationResponse.finResult?.result?.generatedAllocation != null) {
  for (var allocation in allocationResponse.finResult!.result!.generatedAllocation!) {
    print("当前资产大类：${allocation.asset}，大类权重：${allocation.weight}");
    for (var subWeight in allocation.subAssetClassWeight) {
      print("子资产类别：${subWeight.key}，子资产权重：${subWeight.value}");
    }
  }
}

内容的提问来源于stack exchange，提问作者Pallavi Tapkir