import 'package:json_annotation/json_annotation.dart'; part 'test_model.g.dart'; @JsonSerializable() class TestModel { @JsonKey(name: 'test_name') String? name; @JsonKey(defaultValue: '男') String? sex; int? age; TestModel({this.name,this.sex,this.age}); factory TestModel.fromJson(Map json) => _$TestModelFromJson(json); Map toJson() => _$TestModelToJson(this); }