从服务器获取JSON数据，但查询字段时显示错误

问题描述

我能够从Flutter应用程序中的服务器成功获取JSON数据，但是在查询列表视图生成器的字段时却无法执行此操作，并且出现错误

JSON数据

{
    "error": "false","content": {
            "16": [
                [
                    {
                        "sod_pk": "31688","soh_fk": "23660","sqd_fk": "33294","order_header": {
                            "soh_pk": "23660","order_no": "16",}
                    }
                ],[
                    {
                        "sod_pk": "31689","sqd_fk": "33293",}
                    }
                ]
            ],"18": [
                [
                    {
                        "sod_pk": "31744","soh_fk": "23702","sqd_fk": "33354","order_header": {
                            "soh_pk": "23702","order_no": "18",[
                    {
                        "sod_pk": "31745","sqd_fk": "33356",]
        }
    }

呼叫

 orderdetail = OrderModel.fromJson(json.decode(response.body));

我遇到的错误在这里

VERBOSE-2：ui_dart_state.cc（166）]未处理的异常：类型'（动态） => Null'不是'f'的'（String，dynamic）=> void'类型的子类型

发生错误的功能

OrderModel.fromJson(Map<String,dynamic> json) {
        error = json['error'];
        if (json['content'] != null) {
          content = new List<OrderContent>();
    
         //here the error occurs
          json['content'].forEach((v) {
            content.add(new OrderContent.fromJson(v));
          });
        }
      }

订购内容分类

class OrderContent {
  String code;
  String name;

  String ordernumber;
  var order_header;

  OrderContent({this.code,this.name,this.ordernumber,this.order_header});

  OrderContent.fromJson(Map<String,dynamic> json) {
    code = json['code'];
    name = json['name'];
    ordernumber = json['order_no'];
    order_header = json["order_header"];
  }

  Map<String,dynamic> toJson() {
    final Map<String,dynamic> data = new Map<String,dynamic>();
    data['id'] = this.code;
    data['name'] = this.name;
    data['order_header'] = this.order_header;
    data['order_no'] = this.ordernumber;
    return data;
  }
}

从JSON数据中，我无法从列表中获取任何字段，也无法从嵌套的order_header中获取

如何从上面显示的JSON模型获取列表视图构建器的数据？

解决方法

您的json与您要使用的json不匹配。再次阅读您的代码，我确定您会明白的。

flutter-listview json