json_serializable 无法反序列化

Posted 2023-03-31

【中文标题】json_serializable 无法反序列化

【英文标题】：json_serializable fails to deserialize

【发布时间】：2019-02-26 11:15:21

【问题描述】：

我正在尝试将 json 支持添加到我的颤振项目中，但很难做到正确。

我喜欢颤振，但说到 json，我希望使用 gson。

我创建了一个小项目来说明我的问题。

请关注https://bitbucket.org/oakstair/json_lab

我得到了错误 在尝试运行简单的 to/from json 测试时，类型 'Match' 不是类型转换中类型 'Map' 的子类型。

这里显然有一些我想念的东西！

提前感谢暴风雨的斯德哥尔摩！

import 'package:json_annotation/json_annotation.dart';

part 'json_lab.g.dart';

@JsonSerializable()
class Match 
  int home;
  int away;
  double homePoints;
  double awayPoints;

  Match(this.home, this.away, this.homePoints, this.awayPoints);

  factory Match.fromJson(Map<String, dynamic> json) => _$MatchFromJson(json);
  Map<String, dynamic> toJson() => _$MatchToJson(this);


@JsonSerializable()
class Tournament 

  List<String> participants; // Teams or Players.
  List<List<Match>> table = new List<List<Match>>();

  Tournament(this.participants, this.table);

  factory Tournament.fromJson(Map<String, dynamic> json) => _$TournamentFromJson(json);
  Map<String, dynamic> toJson() => _$TournamentToJson(this);

【问题讨论】：

你能提供你打算接收的json样本吗？

【参考方案1】：

因为我看不到您的 json 数据，所以我对您提供的有关命名对象的信息做出了假设。您需要更改以下内容以匹配 json 名称（区分大小写）。

尝试以下方法来创建您的 Match 对象

@JsonSerializable(nullable: true) //allow null values
class Match extends Object with _$MatchSerializerMaxin 
  int home;
  int away;
  double homePoints;
  double awayPoints;

  Match(this.home, this.away, this.homePoints, this.awayPoints);

  factory Match.fromJson(Map<String, dynamic> json) => _$MatchFromJson(json);

  Map<String, dynamic> toMap() 
    var map = new Map<String, dynamic>();

    map["Home"] = home;
    map["Away"] = away;
    map["HomePoints"] = homePoints;
    map["AwayPoints"] = awayPoints;

    return map;
  

  Match.fromMap(Map map)
    try
      home = map["Home"] as int;
      away =  map["Away"] as int;
      homePoints = map["HomePoints"] as double;
      awayPoints = map["AwayPoints"] as double;

    catch(e)
      print("Error Match.fromMap: $e");
    
  


Match _$MatchFromJson(Map<String, dynamic> json)
  Match match = new Match(
    home: json['Home'] as int,
    away: json['Away'] as int,
    homePoints: json['HomePoints'] as double,
    awayPoints: json['AwayPoints'] as double,
  );

    return match;


abstract class _$MatchSerializerMaxin 
  int get home;
  int get away;
  double get homePoints;
  double get awayPoints;

  Match<String, dynamic> toJson() => <String, dynamic>
    'Home' : home,
    'Away' : away,
    'HomePoints' : homePoints,
    'AwayPoints' : awayPoints
  ;

【参考方案2】：

我刚刚向 repo 提交了这个问题的解决方案。

我必须添加explicitToJson。

@JsonSerializable(explicitToJson: true)