Hive: Arguments are missing in constructor of TypeAdapter from extended class

[giandifra]

Steps to Reproduce
I have created TypeAdapter from this comment to use extended class.

Code sample
pet.dart

import 'package:hive/hive.dart';

class Pet extends Equatable {
  @HiveField(0)
  final String name;

  @HiveField(1)
  final int age;

  Pet(this.name, this.age);

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

dog.dart

import 'package:hive/hive.dart';
import 'pet.dart';

part 'dog.g.dart';

@HiveType(typeId: 1)
class Dog extends Pet {
  Dog(String name, int age) : super(name, age);
}

dog.g.dart

// GENERATED CODE - DO NOT MODIFY BY HAND

part of 'dog.dart';

// **************************************************************************
// TypeAdapterGenerator
// **************************************************************************

class DogAdapter extends TypeAdapter<Dog> {
  @override
  final typeId = 1;

  @override
  Dog read(BinaryReader reader) {
    var numOfFields = reader.readByte();
    var fields = <int, dynamic>{
      for (var i = 0; i < numOfFields; i++) reader.readByte(): reader.read(),
    };
    return Dog();
  }

  @override
  void write(BinaryWriter writer, Dog obj) {
    writer
      ..writeByte(2)
      ..writeByte(0)
      ..write(obj.name)
      ..writeByte(1)
      ..write(obj.age);
  }
}

How you can see, there is an error in the constructor of Dog in TypeAdapter, arguments are missing.

Version

• Flutter version: 1.15.2-pre.36
• Flutter channel: master
• hive: ^1.4.0+1
• hive_flutter: ^0.3.0+1
• hive_generator: ^0.7.0

[leisim]

Unfortunately, only zero-argument constructors and constructors which use Initializing parameters (like "Pet(this.name, this.age)") can be used.

[yringler]

I just stumbled into this.
For others who see this: that just means that a base class has to be non-final, and either have no constructor or a constructor with no arguments.
I do like my finals, but not too bad.

[mohammadne]

my problem is that I am using JsonSerializable for my classes and if I not specify the constructor, I will get
The class `Pet` has no default constructor.
so I have to use constructor for that.

any help is appreciated.

[mohammadne]

is there any way to fix the constructor issue ?

[yringler]

If you don't specify a constructor, then there's an implicit default constructor. Can you paste your class?

[mohammadne]

If you don't specify a constructor, then there's an implicit default constructor. Can you paste your class?

https://github.com/hivedb/hive/issues/442#issuecomment-720373939

[TheMisir]

Duplicate of #442