我正在解码响应正文,但出现错误:
'List<dynamic>' is not a subtype of type 'List<Example>'
我正在解析json对象的json数组,其中一个字段也是对象列表,并且我怀疑我的问题是由此引起的。我也在使用json_serializable库。下面是我的代码,我省略了一些字段并更改了一些变量名,但是它表示相同的代码:
import 'package:json_annotation/json_annotation.dart'; part 'example_model.g.dart'; @JsonSerializable() class Example { (some fields here) final List<Random> some_urls; final List<String> file_urls; const Example({ (some fields here) this.some_urls, this.file_urls, }); factory Example.fromJson(Map<String, dynamic> json) => _$ ExampleFromJson(json); } @JsonSerializable() class Random { final String field_1; final int field_2; final int field_3; final int field_4; final bool field_5; constRandom( {this.field_1, this.field_2, this.field_3, this.field_4, this.field_5}); factory Random.fromJson(Map<String, dynamic> json) => _$RandomFromJson(json); }
来自json_serializable制作的.g dart文件(省略了编码部分):
Example _$ExampleFromJson(Map<String, dynamic> json) { return Example( some_urls: (json['some_urls'] as List) ?.map((e) => e == null ? null : Random.fromJson(e as Map<String, dynamic>)) ?.toList(), file_urls: (json['file_urls'] as List)?.map((e) => e as String)?.toList(), } Random _$RandomFromJson(Map<String, dynamic> json) { return Random( field_1: json['field_1'] as String, field_2: json['field_2'] as int, field_3: json['field_3'] as int, field_4: json['field_4'] as int, field_5: json['field_5'] as bool); }
这是我将来的功能:
Future<List<Example>> getData(int ID, String session) { String userID = ID.toString(); var url = BASE_URL + ":8080/example?userid=${userID}"; return http.get(url, headers: { "Cookie": "characters=${session}" }).then((http.Response response) { if (response.statusCode == 200) { var parsed = json.decode(response.body); List<Example> list = parsed.map((i) => Example.fromJson(i)).toList(); return list; } }).catchError((e)=>print(e)); }
此代码创建了一个 List<dynamic>
List<dynamic>
parsed.map((i) => Example.fromJson(i)).toList();
用代替
List<Example> list = List<Example>.from(parsed.map((i) => Example.fromJson(i)));
要不就
var /* or final */ list = List<Example>.fromn(parsed.map((i) => Example.fromJson(i)));
也可以看看