在flutter中解析嵌套的JSON列表时出错

Posted 2023-02-23

【中文标题】在flutter中解析嵌套的JSON列表时出错

【英文标题】：Error in parsing nested JSON list in flutter

【发布时间】：2019-06-17 02:50:45

【问题描述】：

调用 API 但显示错误，我无法解析 bean 类中的数据。

我的回应：

   
"error":"0",
"status":200,
"deliveryCharge":"14.00",
"image_base_url":"http:\/\/xxxxx.tk\/assets\/event\/image\/",
"image_logo_url":"http:\/\/xxxxx.tk\/assets\/event\/logo\/",
"eventList":[

"event_id":"1",
"event_name":"Syscraft Premier League",
"event_location":"12 ny valleys",
"event_type_id":"15",
"start_date":"2019-01-10 03:21:00",
"end_date":"2019-01-26 16:10:00",
"event_logo":"f4f0bfc168a3816891e2749232c5243f.jpg"
,

"event_id":"3",
"event_name":"Republic Day Event 2019",
"event_location":"AH-654 Villa No. 42 New Township New Township",
"event_type_id":"1",
"start_date":"2019-01-26 00:00:00",
"end_date":"2019-01-26 11:55:00",
"event_logo":"3a4a7fabbbd7ed8febf67bacda71ae48.jpg"

]

调用接口

  Future<List<EventResponse>> fetchEvent( ) async 

String url='http://xxxxxxxxxxxxxxx.tk/api/userapp/event/lists';
var headers = new Map();
headers['Auth-Key'] = 'OCDOC@2018';
headers['End-Client'] = 'OCDOC';
var body = new Map();
headers['schedule'] = 'present';
http.Response res = await http.post(url,headers: headers, body: body);
final Map<String,dynamic> parsed=json.decode(res.body); // post api call
print("Reposnce Event:---"+parsed.toString());

我的豆类

class EventResponse


String error;
  int status;
  String deliveryCharges;
  String imageBaseUrl;
  String imageLogoUrl;
  List<Event> eventList;

  EventResponse(
             this.error,
             this.status,
             this.deliveryCharges,
             this.imageBaseUrl,
             this.imageLogoUrl,
             this.eventList
               );

  factory EventResponse.convertEventResponse(Map<String,dynamic> json)
    return EventResponse(
                            error: json['error'],
                            status:  json['status'],
                            deliveryCharges:  json['deliveryCharge'],
                            imageBaseUrl:  json['image_base_url'],
                            imageLogoUrl:  json['image_logo_url'],
                            eventList:  json['eventList']);

  
class Event

  String eventId;
  String eventName;
  String location;
  String event_logo;

  Event(
    this.eventId,
    this.eventName,
    this.location,
    this.event_logo,
  );

  factory Event.convertEvent(Map<String,dynamic> json)
    return Event(
      eventId: json['event_id'],
      eventName:  json['event_name'],
      location:  json['event_location'],
      event_logo:  json['event_logo'],

    );

显示错误

_InternalLinkedHashMap<dynamic, dynamic> is not a subtype of type Map<String, String>

【参考方案1】：

像这样重写EventResponse：

class EventResponse 
  String error;
  int status;
  String deliveryCharges;
  String imageBaseUrl;
  String imageLogoUrl;
  List<Event> eventList;

  EventResponse(
      this.error,
      this.status,
      this.deliveryCharges,
      this.imageBaseUrl,
      this.imageLogoUrl,
      this.eventList);

  factory EventResponse.convertEventResponse(Map<String, dynamic> json) 
    List<dynamic> events = json['eventList'];
    List<Event> eventList = events.map((e) => Event.convertEvent(e)).toList();
    return EventResponse(
        error: json['error'],
        status: json['status'],
        deliveryCharges: json['deliveryCharge'],
        imageBaseUrl: json['image_base_url'],
        imageLogoUrl: json['image_logo_url'],
        eventList: eventList,
        );
  

【参考方案2】：

我已经像@Richard Heap 一样更改了EventResponse。

factory EventResponse.convertEventResponse(Map<String, dynamic> json) 
List<dynamic> events = json['eventList'];
List<Event> eventList = events.map((e) => Event.convertEvent(e)).toList();
return EventResponse(
    error: json['error'],
    status: json['status'],
    deliveryCharges: json['deliveryCharge'],
    imageBaseUrl: json['image_base_url'],
    imageLogoUrl: json['image_logo_url'],
    eventList: eventList,
    );
  

我需要更改的另一件事是当我发布parameters 和headers 时需要将他们的Map() 定义为Map<String,String>()。

 Future<EventResponse> fetchEvent( ) async  // here i change Future type

String url='http://xxxxxxx-oceanapparel.tk/api/userapp/event/lists';
var headers = new Map<String, String>(); //here i defined Map type
headers['Auth-Key'] = 'OCDOC@2018';
headers['End-Client'] = 'OCDOC';
var body = new Map<String, String>(); //here i defined Map type
headers['schedule'] = 'present';
http.Response res = await http.post(url,headers: headers, body: body);

print("Reposnce Event:---"+res.body);