How to Generate Json_Serializable Dart (Flutter) on Inheritance class?

Question

Hello i have 2 parent class Student and Room, which two of them inheritance class model StudentModel and RoomModel, i am try to generate json converter using Json_Serializable Library on Model Class, but when i try to generate with build_runner its show error like this :

My Code

import 'package:equatable/equatable.dart';
import 'package:json_annotation/json_annotation.dart';

part 'student.g.dart';

/// * Student & StudentModel

class Student extends Equatable {
  final int id;
  final String name;
  final Room studentRoom;

  const Student({this.id = 0, this.name = "", this.studentRoom = const Room()});

  @override
  List<Object?> get props => [id, name];
}

@JsonSerializable(explicitToJson: true)
class StudentModel extends Student {
  const StudentModel({int id = 0, String name = "", RoomModel studentRoom = const RoomModel()});

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

  Map<String, dynamic> toJson() => _$StudentModelToJson(this);
}

/// * Room & RoomModel

class Room extends Equatable {
  final int id;
  final String roomName;

  const Room({this.id = 0, this.roomName = ""});

  @override
  List<Object?> get props => [id, roomName];
}

@JsonSerializable()
class RoomModel extends Room {
  const RoomModel({int id = 0, String roomName = ""}) : super(id: id, roomName: roomName);

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

  Map<String, dynamic> toJson() => _$RoomModelToJson(this);
}

Response Builder

Could not generate `toJson` code for `studentRoom`.
To support the type `Room` you can:
* Use `JsonConverter`
  https://pub.dev/documentation/json_annotation/latest/json_annotation/JsonConverter-class.html
* Use `JsonKey` fields `fromJson` and `toJson`
  https://pub.dev/documentation/json_annotation/latest/json_annotation/JsonKey/fromJson.html
  https://pub.dev/documentation/json_annotation/latest/json_annotation/JsonKey/toJson.html
package:untitled1/model/student.dart:11:14
   ╷
11 │   final Room studentRoom;
   │              ^^^^^^^^^^^
   ╵

The problem is builder is search for Room toJson and fromJson not RoomModel, i used jsonKey but it doesn't help, how to fix that problem? Thanks.

Nikunj Ramani · Answer 1 · 2022-07-06T09:56:51.713

use following code

import 'package:equatable/equatable.dart';
import 'package:json_annotation/json_annotation.dart';

part 'student.g.dart';

class Student extends Equatable {
  final int id;
  final String name;
  final Room studentRoom;
  const Student({this.id = 0, this.name = "", this.studentRoom = const Room()});

  @override
  List<Object?> get props => [id, name];
}

@JsonSerializable(explicitToJson: true)
class StudentModel extends Student {
  StudentModel({int id = 0, String name = ""});

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

  Map<String, dynamic> toJson() => _$StudentModelToJson(this);
}

/// * Room & RoomModel

class Room extends Equatable {
  final int id;
  final String roomName;

  const Room({this.id = 0, this.roomName = ""});

  @override
  List<Object?> get props => [id, roomName];
}

@JsonSerializable()
class RoomModel extends Room {
  const RoomModel({int id = 0, String roomName = ""})
      : super(id: id, roomName: roomName);

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

  Map<String, dynamic> toJson() => _$RoomModelToJson(this);
}

Yes its working and build, but the problem is i cant access studentRoom on student class or studentModel class, cause they dont have studentRoom variable neither. — Sapatekno, Jul 06 '22 at 05:21
@Sapatekno I have updated the code. please try this code you can access room model class from student now — Nikunj Ramani, Jul 06 '22 at 09:57

How to Generate Json_Serializable Dart (Flutter) on Inheritance class?

1 Answers1