Flutter - Json 对象数组

Posted 2023-02-23

【中文标题】Flutter - Json 对象数组

【英文标题】：Flutter - Json array of objects

【发布时间】：2019-12-21 19:57:27

【问题描述】：

我将如何解析嵌套的对象数组，例如下面的对象。

    "status": "success",
    "code": 200,
    "message": "The request was successful",
    "data": [
        
            "name": "Abu Dhabi",
            "id": 4139,
            "parent": 5153,
            "type": "city",
            "imageURL": ""

        ,
        
            "name": "Croatia",
            "id": 5037,
            "parent": 6886,
            "type": "country",
            "imageURL": ""

        ,
     ]

我目前正在进行 API 调用，它以如上所示的格式返回数据。

我的api调用如下：

  Future<Location> getLocations() async 
    final response =
        await http.get('$endpoint/locations', headers: authenticatedHeader);

    if (response.statusCode == 200) 
      final responseJson = json.decode(response.body);

      // If server returns an OK response, parse the JSON.

      return Location.fromJson(responseJson);
     else 
      // If that response was not OK, throw an error.
      throw Exception('Failed to load post');
    
  

然后我有一个如下位置类：

class Location 
  String name;
  int id;
  int parent;
  String type;
  String imageURL;

  Location(
      this.name, this.id, this.parent, this.type, this.imageURL);

  factory Location.fromJson(Map<String, dynamic> json) =>
      _locationFromJson(json);


Location _locationFromJson(Map<String, dynamic> json) 
  return Location(
    name: json['name'] as String,
    id: json['id'] as int,
    parent: json['parent'] as int,
    type: json['type'] as String,
    imageURL: json['imageURL'] as String
  );

我希望能够使用 listview builder 检索上述所有位置，并为每个位置创建一个 listtile。

如何正确解析 JSON？

【问题讨论】：

return Location.fromJson(responseJson.data);

【参考方案1】：

关注这个 url 你会更多地了解 json 解析。 https://medium.com/flutter-community/parsing-complex-json-in-flutter-747c46655f51

这里是你正在寻找的代码，我在资产中使用了静态 json，所以你必须用你的 resonse 替换。

    import 'dart:async' show Future;
    import 'package:flutter/services.dart' show rootBundle;
    import 'dart:convert';
    import 'package:flutter_json/model/location_model.dart';

    Future<String> _loadlocationAsset() async 
    return await rootBundle.loadString('assets/location.json');
    

    Future loadLocation() async 
    String jsonLocation = await _loadlocationAsset();
    final jsonResponse = json.decode(jsonLocation);
    LocationData location = new LocationData.fromJson(jsonResponse);
    print(location.data[0].name);
    

数据模型

     class LocationData 
        final int code;
        final String status;
        final String message;
        final List<Data> data;

        LocationData(this.code, this.status,this.message, this.data);

        factory LocationData.fromJson(Map<String, dynamic> parsedJson)

            var list = parsedJson['data'] as List;
            print(list.runtimeType);
            List<Data> dataList = list.map((i) => Data.fromJson(i)).toList();


            return LocationData(
                code: parsedJson['code'],
                status: parsedJson['status'],
                message: parsedJson['message'],
                data: dataList
            );
        
        

        class Data 
        final int id;
        final int parent;
        final String name;
        final String type;
        final String imageURL;

        Data(this.id, this.parent,this.name,this.type,this.imageURL);

        factory Data.fromJson(Map<String, dynamic> parsedJson)
            return Data(
                id:parsedJson['id'],
                parent:parsedJson['parent'],
                name:parsedJson['name'],
                type:parsedJson['type'],
                imageURL:parsedJson['imageURL']
            );
        
        

【讨论】：

使用内置值类型来轻松对复杂对象进行 JSON 序列化。