Arrays 无法将数据从JSON获取到Flatter中的字段

Arrays 无法将数据从JSON获取到Flatter中的字段,arrays,json,flutter,flutter-listview,flutter-pageview,Arrays,Json,Flutter,Flutter Listview,Flutter Pageview,我能够从颤振应用程序中的服务器获取JSON数据。我需要在PageView.builder和嵌套的ListView.builder中显示数据,我已经创建了这个模型 该守则要求实施 orderdetail = NewOrder.fromJson(json.decode(response.body)); 这是我能够从颤振应用程序中的服务器获取的JSON数据 { "error": "false", "content": [

我能够从颤振应用程序中的服务器获取JSON数据。我需要在PageView.builder和嵌套的ListView.builder中显示数据,我已经创建了这个模型

该守则要求实施

orderdetail = NewOrder.fromJson(json.decode(response.body));
这是我能够从颤振应用程序中的服务器获取的JSON数据

{
    "error": "false",
    "content": [
        {
            "comp_code": "4",
            "comp_name": "KMT OVERSEAS",
            "order_no": "16",
            "order_items": [
                {
                    "comp_code": "4",
                    "comp_name": "KMT OVERSEAS",
                    "order_no": "16",
                },
                {
                    "comp_code": "4",
                    "comp_name": "KMT OVERSEAS",
                    "order_no": "16",
                }
            ]
        },
        {
            "comp_code": "4",
            "comp_name": "KMT OVERSEAS",
            "order_no": "18",
            "order_items": [
                {
                    "comp_code": "4",
                    "comp_name": "KMT OVERSEAS",
                    "order_no": "18",
                },
                {
                    "comp_code": "4",
                    "comp_name": "KMT OVERSEAS",
                    "order_no": "18",

                },
                {
                    "comp_code": "4",
                    "comp_name": "KMT OVERSEAS",
                    "order_no": "18",
                },
               
            ]
        }
    ]
}
我用于它的代码是用于获取有状态小部件中的数据

  Future<Payload> getdetailsoforders(String userid, String companycode) async {

    SharedPreferences sharedPreferences = await SharedPreferences.getInstance();
    Map data = {
      'user_id': userid,
      'company_code':companycode

    };

    var response = await http.post(newapi, body: data);
    if(response.statusCode == 200) {
     jsonResponse = json.decode(response.body);
      print("jsonrespnse");
      print(jsonResponse);
 }
    

  } else {
  setState(() {
    _isLoading = false;
  });


  print('login error');
  print(response.body);
}

  }
Future getdetailsoforders(字符串用户ID、字符串公司代码)异步{
SharedReferences SharedReferences=等待SharedReferences.getInstance();
地图数据={
“用户id”:用户id,
“公司代码”:公司代码
};
var response=wait http.post(newapi,body:data);
如果(response.statusCode==200){
jsonResponse=json.decode(response.body);
打印(“JSONResponse”);
打印(jsonResponse);
}
}否则{
设置状态(){
_isLoading=false;
});
打印(“登录错误”);
打印(响应.正文);
}
}
下面是我实现的NewOrder模型类

import 'newitem.dart';

class NewOrder {
  NewOrder({
    this.sohPk,
    this.orderNo,
    this.newItem,
  });

  String sohPk;
  String orderNo;
 NewItem newItem;

  factory NewOrder.fromJson(Map<String, dynamic> json) => NewOrder(
    sohPk: json["soh_pk"],
    orderNo: json["order_no"],
  newItem:NewItem.fromJson(json['order_items'])
  );

  Map<String, dynamic> toJson() => {
    "soh_pk": sohPk,
    "order_no": orderNo,
   'order_items': newItem.toJson()
  };
}
导入“newitem.dart”;
类新订单{
新秩序({
这个,sohPk,,
这是订单号,
这个新项目,
});
字符串sohPk;
字符串orderNo;
NewItem NewItem;
工厂NewOrder.fromJson(映射json)=>NewOrder(
sohPk:json[“soh_pk”],
orderNo:json[“order_no”],
newItem:newItem.fromJson(json['order\u items'])
);
映射到JSON()=>{
“搜狐pk”:搜狐pk,
“订单号”:订单号,
'order_items':newItem.toJson()
};
}
我实现的NewPlayLoadClass就在这里

导入“package:dataproject2/newmodel/neworder.dart”

class NewPayLoad {
  String error;
  List<NewOrder> content;

  NewPayLoad({this.error, this.content});

  NewPayLoad.fromJson(Map<String, dynamic> json) {
    error = json['error'];
    if (json['content'] != null) {
      content = new List<NewOrder>();
      json['content'].forEach((v) {
        content.add(new NewOrder.fromJson(v));
      });
    }
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = new Map<String, dynamic>();
    data['error'] = this.error;
    if (this.content != null) {
      data['content'] = this.content.map((v) => v.toJson()).toList();
    }
    return data;
  }
}
class-NewPayLoad{
字符串错误;
列出内容;
NewPayLoad({this.error,this.content});
fromJson(映射json){
error=json['error'];
如果(json['content']!=null){
内容=新列表();
json['content'].forEach((v){
add(NewOrder.fromJson(v));
});
}
}
映射到JSON(){
最终地图数据=新地图();
数据['error']=this.error;
如果(this.content!=null){
data['content']=this.content.map((v)=>v.toJson()).toList();
}
返回数据;
}
}
我得到的错误就在这里

以下NoSuchMethodError在生成时抛出 PageViewClass(脏,状态:_PageViewClassState#98a84):getter 对null调用了“content”。接收方:null尝试调用:content

我无法理解我的代码有什么问题,以及如何解决它 请进一步指导

使用以下代码

class NewOrder {
  String _error;
  List<Content> _content;

  NewOrder({String error, List<Content> content}) {
    this._error = error;
    this._content = content;
  }

  String get error => _error;
  set error(String error) => _error = error;
  List<Content> get content => _content;
  set content(List<Content> content) => _content = content;

  NewOrder.fromJson(Map<String, dynamic> json) {
    _error = json['error'];
    if (json['content'] != null) {
      _content = new List<Content>();
      json['content'].forEach((v) {
        _content.add(new Content.fromJson(v));
      });
    }
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = new Map<String, dynamic>();
    data['error'] = this._error;
    if (this._content != null) {
      data['content'] = this._content.map((v) => v.toJson()).toList();
    }
    return data;
  }
}

class Content {
  String _compCode;
  String _compName;
  String _orderNo;
  List<OrderItems> _orderItems;

  Content(
      {String compCode,
      String compName,
      String orderNo,
      List<OrderItems> orderItems}) {
    this._compCode = compCode;
    this._compName = compName;
    this._orderNo = orderNo;
    this._orderItems = orderItems;
  }

  String get compCode => _compCode;
  set compCode(String compCode) => _compCode = compCode;
  String get compName => _compName;
  set compName(String compName) => _compName = compName;
  String get orderNo => _orderNo;
  set orderNo(String orderNo) => _orderNo = orderNo;
  List<OrderItems> get orderItems => _orderItems;
  set orderItems(List<OrderItems> orderItems) => _orderItems = orderItems;

  Content.fromJson(Map<String, dynamic> json) {
    _compCode = json['comp_code'];
    _compName = json['comp_name'];
    _orderNo = json['order_no'];
    if (json['order_items'] != null) {
      _orderItems = new List<OrderItems>();
      json['order_items'].forEach((v) {
        _orderItems.add(new OrderItems.fromJson(v));
      });
    }
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = new Map<String, dynamic>();
    data['comp_code'] = this._compCode;
    data['comp_name'] = this._compName;
    data['order_no'] = this._orderNo;
    if (this._orderItems != null) {
      data['order_items'] = this._orderItems.map((v) => v.toJson()).toList();
    }
    return data;
  }
}

class OrderItems {
  String _compCode;
  String _compName;
  String _orderNo;

  OrderItems({String compCode, String compName, String orderNo}) {
    this._compCode = compCode;
    this._compName = compName;
    this._orderNo = orderNo;
  }

  String get compCode => _compCode;
  set compCode(String compCode) => _compCode = compCode;
  String get compName => _compName;
  set compName(String compName) => _compName = compName;
  String get orderNo => _orderNo;
  set orderNo(String orderNo) => _orderNo = orderNo;

  OrderItems.fromJson(Map<String, dynamic> json) {
    _compCode = json['comp_code'];
    _compName = json['comp_name'];
    _orderNo = json['order_no'];
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = new Map<String, dynamic>();
    data['comp_code'] = this._compCode;
    data['comp_name'] = this._compName;
    data['order_no'] = this._orderNo;
    return data;
  }
}
类NewOrder{
字符串错误;
列表内容;
NewOrder({字符串错误,列表内容}){
这是错误;
这._content=内容;
}
字符串获取错误=>\u错误;
设置错误(字符串错误)=>\u错误=错误;
列表获取内容=>\u内容;
设置内容(列表内容)=>\u内容=内容;
fromJson(映射json){
_error=json['error'];
如果(json['content']!=null){
_内容=新列表();
json['content'].forEach((v){
_content.add(newcontent.fromJson(v));
});
}
}
映射到JSON(){
最终地图数据=新地图();
数据['error']=此错误;
如果(此._内容!=null){
data['content']=this._content.map((v)=>v.toJson()).toList();
}
返回数据;
}
}
课堂内容{
字符串编码;
字符串_compName;
字符串_orderNo;
列出订购项目;
内容(
{字符串编码,
字符串compName,
字符串orderNo,
列出订单项}){
这个。_compCode=compCode;
这个._compName=compName;
这个。_orderNo=orderNo;
这是._orderItems=orderItems;
}
字符串get compCode=>\u compCode;
设置compCode(字符串compCode)=>\u compCode=compCode;
字符串get compName=>\u compName;
设置compName(字符串compName)=>\u compName=compName;
字符串get orderNo=>\u orderNo;
设置orderNo(字符串orderNo)=>\u orderNo=orderNo;
List get orderItems=>\u orderItems;
设置orderItems(列出orderItems)=>\u orderItems=orderItems;
Content.fromJson(映射json){
_compCode=json['comp_code'];
_compName=json['comp_name'];
_orderNo=json['order_no'];
如果(json['order_items']!=null){
_orderItems=新列表();
json['order_items'].forEach((v){
_add(neworderItems.fromJson(v));
});
}
}
映射到JSON(){
最终地图数据=新地图();
数据['comp_code']=此;
数据['comp_name']=此;
数据['order_no']=此;
if(this.\u orderItems!=null){
data['order\u items']=这个.orderItems.map((v)=>v.toJson()).toList();
}
返回数据;
}
}
类OrderItems{
字符串编码;
字符串_compName;
字符串_orderNo;
OrderItems({String compCode,String compName,String orderNo}){
这个。_compCode=compCode;
这个._compName=compName;
这个。_orderNo=orderNo;
}
字符串get compCode=>\u compCode;
设置compCode(字符串compCode)=>\u compCode=compCode;
字符串get compName=>\u compName;
设置compName(字符串compName)=>\u compName=compName;
字符串get orderNo=>\u orderNo;
设置orderNo(字符串orderNo)=>\u orderNo=orderNo;
fromJson(映射json){
_compCode=json['comp_code'];
_compName=json['comp_name'];
_orderNo=json['order_no'];
}
映射到JSON(){
最终地图数据=新地图();
数据['comp_code']=此;
数据['comp_name']=此;
数据['order_no']=此;
返回数据;
}
}

@chunhunghan您好,我看到您解决了一个类似的问题,请帮助我解决这个问题,我试图实现您对这个问题的解决方案,但没有成功,请指导我进一步感谢您对JSON数据框架建模的帮助。我还要求你做一件事,请帮助我调用元素,因为它太复杂了,我无法做出正确的选择。每个示例一个就足够了,请指导我获取OrderItemsyes的元素,在将来的函数中使用