错误：类型 'List<dynamic>' 不是类型 'Map<String, dynamic>' 的子类型

Question

所以我创建了一个应用程序来通过 api 读取数据并尝试解析 JSON api

这是我的 Error screenshot

我尝试将其更改为列表，但它仍然读取错误

这是我的代码 elephant.dart

@JsonSerializable()
class ElephantList{
  ElephantList({this.biodata});
  final List<Elephant> biodata;
  factory ElephantList.fromJson(Map<String, dynamic> json) => _$ElephantListFromJson(json);
  Map<String, dynamic> toJson() => _$ElephantListToJson(this);
}

@JsonSerializable()
class Elephant{
  Elephant({this.name, this.affiliation, this.species,
  this.sex, this.fictional, this.dob, this.dod, this.wikilink, this.image, this.note});
  //final String index;
  final String name;
  final String affiliation;
  final String species;
  final String sex;
  final String fictional;
  final String dob;
  final String dod;
  final String wikilink;
  final String image;
  final String note;

  factory Elephant.fromJson(Map<String, dynamic> json) => _$ElephantFromJson(json);
  Map<String, dynamic> toJson() => _$ElephantToJson(this);
}

Future<ElephantList> getElephantList() async{
  const url = 'https://elephant-api.herokuapp.com/elephants/sex/male';
  final response = await http.get(url);
  if(response.statusCode ==  200){
    return ElephantList.fromJson(json.decode(response.body));
  }else{
    throw HttpException('Error ${response.reasonPhrase}', uri: Uri.parse(url));
  }
}

如何纠正这个错误？ 请帮忙

Answer 1

api：https://elephant-api.herokuapp.com/elephants/sex/male 返回一个大象列表，格式为：[Elephant , Elephant , ... ]，而您指定从该请求接收到的 json 是 Map<String, dynamic>，它的格式为：{ elephants : [ ... ] }，所以只需替换每个Map<String, dynamic> 与 List<dynamic>

@JsonSerializable(anyMap: true)
class ElephantList{
  ElephantList({this.biodata});
  final List<Elephant> biodata;
  factory ElephantList.fromJson(List<dynamic> json) => _$ElephantListFromJson(json);
  List<dynamic> toJson() => _$ElephantListToJson(this);
}

@JsonSerializable()
class Elephant{
  Elephant({this.name, this.affiliation, this.species,
  this.sex, this.fictional, this.dob, this.dod, this.wikilink, this.image, this.note});
  //final String index;
  final String name;
  final String affiliation;
  final String species;
  final String sex;
  final String fictional;
  final String dob;
  final String dod;
  final String wikilink;
  final String image;
  final String note;

  factory Elephant.fromJson(Map<String, dynamic> json) => _$ElephantFromJson(json);
  Map<String, dynamic> toJson() => _$ElephantToJson(this);
}

Future<ElephantList> getElephantList() async{
  const url = 'https://elephant-api.herokuapp.com/elephants/sex/male';
  final response = await http.get(url);
  if(response.statusCode ==  200){
    return ElephantList.fromJson(json.decode(response.body));
  }else{
    throw HttpException('Error ${response.reasonPhrase}', uri: Uri.parse(url));
  }
}

编辑：@JsonSerializable 预期 json 为 Map<string,dynamic>，因此要更改预期类型，您应该添加 anyMap: true 我相应地更改了代码