Json 获取问题：'_内部链接dhashmap<；字符串，动态>'；不是类型为'；列表<；动态>'；

我试图从API中获取数据，但一直出现此错误

获取问题：“\u InternalLinkedHashMap”不是“List”类型的子类型

请告诉我如何修复此代码

省道模型

class ComprovanteModel {
  ComprovantesInfoModel jsonResponse;

  String error;

  ComprovanteModel({this.jsonResponse, this.error});

  ComprovanteModel.fromJson(Map<String, dynamic> json)
      : jsonResponse = ComprovantesInfoModel.fromJson(json['json_response']),
        error = '';

  ComprovanteModel.withError(String errorValue)
      : jsonResponse = null,
        error = errorValue;
}

class ComprovanteInfoModel {
  String clientFormalName;
  int volumes;
  int duration;
  CheckpointsModel checkpoint;

  ComprovanteInfoModel({
    this.clientFormalName,
    this.duration,
    this.volumes,
    this.checkpoint,
  });

  ComprovanteInfoModel.fromJson(Map<String, dynamic> json)
      : clientFormalName = json['client_formal_name'],
        checkpoint = CheckpointsModel.fromJson(json['checkpoint']),
        volumes = json['volumes'],
        duration = json['duration'];
}

class CheckpointModel {
  int checkpointId;
  String arrivalTime;
  int status;

  CheckpointModel({
    this.checkpointId,
    this.arrivalTime,
    this.status,
  });

  CheckpointModel.fromJson(Map<String, dynamic> json)
      : checkpointId = json['checkpoint_id'],
        arrivalTime = json['arrival_time'],
        status = json['status'];
}

class CheckpointsModel {
  List<CheckpointModel> checkpoint;

  CheckpointsModel({this.checkpoint});

  CheckpointsModel.fromJson(List<dynamic> jsonList)
      : checkpoint = jsonList.map((e) => CheckpointModel.fromJson(e)).toList();
}

我想访问检查点项，然后是资源项（我认为这与检查点的过程相同）。我用的是这个列表，但我觉得不对，我想用的是地图，但我不知道怎么用。请给我指路。

• 更改此项：

  ComprovanteModel.fromJson(Map<String, dynamic> json)
      : jsonResponse = ComprovantesInfoModel.fromJson(json['json_response']),
        error = '';
  

  • 您告诉Flatter您将传递一个类型为

    List

    的对象，但在您发布的json中，

    “checkpoint”：{

    不是一个列表，而是一个映射。但即使如此，这个映射只有一个检查点

  • 来回答你的最后一个问题

  我想访问检查点项，然后访问资源项 思考与检查点的过程相同）

  “资源”：[

  确实是一个地图列表。在您的代码中，您没有发布您的资源模型，但我假设您想要一个

  列表，而不是
  列表，它将如下所示：
  
  class SingleResourceModel {
     String contentType;
     int serviceId;
     String content;
     String contentLabel;
     String uniqueCode;
  
    SingleResourceModel({
      this.contentType,
      this.serviceId,
      this.content,
      this.contentLabel,
      this.uniqueCode
    });
  
    SingleResourceModel.fromJson(Map<String, dynamic> json)
        : contentType = json['content_type'],
          serviceId = json['service_event_effect_id'],
          content = json['content'];
          contentLabel = json['content_label'],
          uniqueCode = json['user_effect_unique_code'];
  }
  class ListResourceModel {
    List<SingleResourceModel> resourcesList;
  
    ListResourceModel({this.resourcesList});
  
    ListResourceModel.fromJson(List<Map<String, dynamic>> jsonList)
        : resourcesList = jsonList.map((e) => SingleResourceModel.fromJson(e)).toList();
  }
  
  现在，您应该准备好了。
  非常感谢MAAN！！！问题解决得很顺利！！非常感谢您！编码快乐：）
   ComprovanteModel.fromJson(Map<String, dynamic> json)
        : jsonResponse = ComprovantesInfoModel.fromJson(json['json_response'][0]), //added [0] here.
          error = '';
  
   CheckpointsModel.fromJson(List<dynamic> jsonList)
        : checkpoint = jsonList.map((e) => CheckpointModel.fromJson(e)).toList();
  }
  
  class SingleResourceModel {
     String contentType;
     int serviceId;
     String content;
     String contentLabel;
     String uniqueCode;
  
    SingleResourceModel({
      this.contentType,
      this.serviceId,
      this.content,
      this.contentLabel,
      this.uniqueCode
    });
  
    SingleResourceModel.fromJson(Map<String, dynamic> json)
        : contentType = json['content_type'],
          serviceId = json['service_event_effect_id'],
          content = json['content'];
          contentLabel = json['content_label'],
          uniqueCode = json['user_effect_unique_code'];
  }
  class ListResourceModel {
    List<SingleResourceModel> resourcesList;
  
    ListResourceModel({this.resourcesList});
  
    ListResourceModel.fromJson(List<Map<String, dynamic>> jsonList)
        : resourcesList = jsonList.map((e) => SingleResourceModel.fromJson(e)).toList();
  }
  
  class CheckpointModel {
    int checkpointId;
    String arrivalTime;
    int status;
    ListResourceModel resourcesList;
  
    CheckpointModel({
      this.checkpointId,
      this.arrivalTime,
      this.status,
      this.resourcesList
    });
  
    CheckpointModel.fromJson(Map<String, dynamic> json)
        : checkpointId = json['checkpoint_id'],
          arrivalTime = json['arrival_time'],
          status = json['status'],
          resourcesList= json['resources'];    
     }