flutter_provider_demo/lib/model/base_model.dart

class BaseModel {
  int id = 0;
}

class BaseEntity {
  int code = 0;
  String msg = "";
  BaseModel? data;
  BaseEntity({required this.code, required this.msg, this.data});
  BaseEntity.fromJson(Map<String, dynamic> json) {
    code = json['code'];
    msg = json['msg'];
    data = json['data'];
  }
  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = <String, dynamic>{};
    data['code'] = code;
    data['msg'] = msg;
    data['data'] = this.data;
    return data;
  }
}